REVIEW URRENT C OPINION
Modifying diet and physical activity to support pregnant women who are overweight or obese Jodie M. Dodd a,b, Cecelia M. O’Brien a,b, and Rosalie M. Grivell a,b
Purpose of review Overweight and obesity represent a significant health burden during pregnancy, placing women and their infants at increased risk of adverse health outcomes. Although there is considerable observational literature describing the effect of gestational weight gain in pregnancy, research efforts have focused on limiting gestational weight gain among pregnant women who are overweight or obese, with limited reporting of clinical outcomes. Recent findings The LIMIT randomized trial recruited 2212 pregnant women with a BMI at least 25 kg/m2. Providing an antenatal dietary and lifestyle intervention was associated with significant improvements in maternal diet and physical activity patterns, and a significant reduction in the risk of infants being born with high birth weight. Summary The findings of the LIMIT randomized trial provide the first evidence that changes in maternal diet and physical activity during pregnancy can reduce the risk of high infant birth weight among women who are overweight or obese, and from a public health perspective, may represent a significant strategy to tackle the increasing problem of childhood and adulthood obesity. Keywords dietary and lifestyle intervention, maternal and infant health outcomes, overweight and obesity, randomized trial, review
INTRODUCTION The World Health Organisation defines individuals as overweight if their BMI is between 25.0 and 29.9 kg/m2, and obese if their BMI is greater than or equal to 30.0 kg/m2 [1]. Worldwide, obesity represents a major health concern, with estimates suggesting approximately 1.5 billion adults are obese [2]. Obesity in pregnancy is increasingly common, and in Australia, as in other developed nations, more than 50% of women are overweight or obese on entering pregnancy [3–5]. Maternal obesity is recognized as the single largest contributor to compromised health during pregnancy [6]. Indeed, maternal obesity is associated with an increased risk of virtually all pregnancy complications, including preeclampsia, gestational diabetes, need for induction of labour, and caesarean birth, in addition to adverse outcomes for the infant, including perinatal death [7]. Furthermore, there is recognition of a link between maternal obesity and a longer-term child health legacy. There are well described associations between maternal overweight and obesity, and infant birth weight above www.co-clinicalnutrition.com
4 kg [7], which in turn, is associated with a greater risk of both child and adult obesity [8–12].
LIMITING GESTATIONAL WEIGHT GAIN There is a considerable observational literature describing the effect of gestational weight gain in pregnancy, with recommendations by maternal BMI category presented by the US based Institute of Medicine suggesting that women who are overweight gain between 7.0 and 11.5 kg, and women who are obese between 5.0 and 9.0 kg [13]. Although
a
School of Paediatrics and Reproductive Health, Robinson Research Institute, University of Adelaide, Adelaide and bDepartment of Perinatal Medicine, Women’s and Babies Division, Women’s and Children’s Hospital, North Adelaide, Australia Correspondence to Professor Jodie M. Dodd, University of Adelaide, Women’s and Children’s Hospital, 72 King William Road, North Adelaide, South Australia 5006, Australia. Tel: +61 8 8161 7619; fax: +61 8 8161 7652; e-mail: [email protected] Curr Opin Clin Nutr Metab Care 2015, 18:318–323 DOI:10.1097/MCO.0000000000000170 Volume 18 Number 3 May 2015
Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
Modifying diet and physical activity to support pregnant women Dodd et al.
KEY POINTS
Advice group) delivered across their pregnancy or to receive standard antenatal care (Standard Care group) [19 ]. The dietary and lifestyle intervention included a combination of dietary, exercise, and behavioural strategies, delivered by a research dietician and trained research assistants [18]. Specifically, dietary information was consistent with the Australian Guide to Healthy Eating [20], in which women were encouraged to reduce their intake of foods high in refined carbohydrates and saturated fats, whereas increasing their intake of fibre, through the consumption of two servings of fruit, five servings of vegetables, and three servings of dairy each day. Physical activity advice focussed on encouraging women to increase their daily walking and incidental activity. In consultation with the research dietician, each woman was encouraged to identify and set achievable goals for dietary and physical activity change, supported to make these changes to their lifestyle, and to self-monitor their progress. Furthermore, each woman was encouraged to identify potential barriers to the implementation of their goals and, using these perceived barriers, were assisted to both problem solve and develop individualized facilitative strategies. At each subsequent contact with the woman, this information was reinforced. The women allocated to receive Standard Care continued their pregnancy care in accordance with statewide and local hospital guidelines, who did not include the provision of dietary or physical activity advice, or information about weight gain during pregnancy [21]. &
Fifty percent of women enter pregnancy with a BMI at least 25 kg/m2, with maternal obesity recognized as the single largest contributor to compromised health during pregnancy. Providing dietary and lifestyle advice to pregnant women who are overweight or obese is associated with a significant 18% relative risk reduction in the chance of an infant with birth weight above 4 kg. Providing dietary and lifestyle advice to pregnant women who are overweight or obese is associated with significant improvements in maternal diet and physical activity patterns. The findings of the LIMIT randomized trial represent a strategy of considerable public health significance in tackling the ongoing and increasing problem of both childhood and adulthood obesity.
many countries globally have adopted these recommendations, there appears to be a lack of international consensus as to the most appropriate content of guidelines addressing maternal gestational weight gain [14], reflecting the lack of a high-quality evidence base. In an attempt to improve the available evidence relating to optimal gestational weight gain, there has been a considerable research focus on evaluating interventions for women who are overweight or obese, with several published systematic reviews and meta-analyses of randomized trials [15–17]. Although the majority of included trials are of relatively small sample size, it would appear from these meta-analyses that providing an antenatal dietary and/or lifestyle intervention for overweight or obese pregnant women is somewhat effective in limiting gestational weight gain [15–17]. Importantly, however, studies conducted to date have largely ignored reporting of clinical maternal and infant outcomes [15–17].
MATERNAL AND INFANT CLINICAL OUTCOMES FROM THE LIMIT RANDOMIZED TRIAL A total of 2212 women participated in the LIMIT randomized trial, of whom 42% of women were overweight, and 58% obese, with the median BMI of the cohort 31.1 kg/m2 [19 ]. For infants born to women who received Lifestyle Advice, there was a significant 18% relative risk reduction in the chance of birth weight above 4.0 kg, when compared with infants born to women who received Standard Care (P ¼ 0.04) [19 ]. Furthermore, there was a significant 41% relative risk reduction in the chance of birth weight above 4.5 kg (P ¼ 0.04), with no increase in the risk of low infant birth weight, for infants born following Lifestyle Advice, when compared with infants born to women who received Standard Care [22 ]. Despite a lack of difference in the use of either antenatal corticosteroids or mean gestational age at birth, infants born to women who received Lifestyle &
METHODOLOGY OF THE LIMIT RANDOMIZED TRIAL In view of the limitations in the literature describing the effects of antenatal dietary and lifestyle interventions on maternal, foetal, neonatal, and infant outcomes, the LIMIT randomized trial was conducted [18], involving 2212 women with a singleton pregnancy and BMI at least 25 kg/m2 [19 ]. Using a computer-generated schedule and central telephone randomization service, women were randomized after providing informed consent either to receive a comprehensive lifestyle intervention (Lifestyle &
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Advice were 53% less likely to be diagnosed with moderate or severe respiratory distress syndrome (P ¼ 0.02) [22 ]. Although the increased diagnosis of respiratory distress syndrome was not associated with a statistically significant difference in the chance of admission to the neonatal nursery, overall, infants born following Lifestyle Advice had a shorter hospital length of stay (P ¼ 0.006) [22 ]. Although there were significant improvements in infant health outcomes, there were no statistically significant differences identified between the treatment groups for any of the maternal antenatal, labour, or birth outcomes which have been previously identified to be increased among women who are overweight or obese [19 ]. &
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THE EFFECT OF THE LIMIT INTERVENTION ON GESTATIONAL WEIGHT GAIN The mean gestational weight gain of women who participated in the LIMIT randomized trial was 9.4 kg, and did not differ significantly between those women who received Lifestyle Advice and those receiving Standard Care [19 ]. When considering the Institute of Medicine weight gain recommendations by early pregnancy BMI category, approximately 42% of all women were considered to have excessive weight gain, with 33% of women gaining weight within the target range [19 ]. The proportion of women within each weight gain range did not differ significantly between the two treatment groups [19 ]. These findings are in contrast to the effect on gestational weight gain reported in systematic reviews [15–17]. However, the intensity of the intervention provided in the LIMIT randomized trial involving three face-to-face sessions and three telephone contacts, is consistent with that reported by the individual included studies, the majority providing between three and six intervention sessions [15–17]. At the time of designing the trial, it was not considered practical to increase the intensity of the intervention further, either from the perspective of a healthcare setting with limited resources or with respect to individual compliance. The issue of compliance with the intervention is particularly relevant, with only 87% of women participating in the LIMIT trial attending their first dietary session, and falling further to 77% for their second dietary session [19 ]. Our findings are consistent with the available literature relating to weight loss interventions in nonpregnant individuals, which indicates that while increasing the number of intervention sessions increases effect, there are issues in maintaining ongoing compliance [23]. &
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THE EFFECT OF THE LIMIT INTERVENTION ON MATERNAL DIET AND PHYSICAL ACTIVITY Although the provision of Lifestyle Advice was not associated with differences in gestational weight gain or total energy intake during pregnancy [19 ], women were successful in making significant improvements to both their diet and physical activity patterns [24 ]. Women who received Lifestyle Advice significantly increased the number of servings per day of fruits and vegetables, and consequently their daily fibre intake, when compared with women who received Standard Care (P < 0.05 for all) [24 ]. Furthermore, women provided with Lifestyle Advice demonstrated a significant reduction in the percentage of their energy intake which was derived from saturated fats (P < 0.05) [24 ]. The healthy eating index, as an assessment of overall dietary quality was significantly improved at both 28 weeks (P < 0.0001) and 36 weeks (P < 0.0001) gestation among women receiving Lifestyle Advice [24 ]. Similar findings of improved dietary intake have been reported in smaller randomized trials involving overweight and obese pregnant women have been described, particularly reduced dietary consumption of saturated fats [25–27], some of which have occurred in the absence of an effect on either reported total energy intake or gestational weight gain [25]. From a mechanistic perspective, there is increasing recognition of the role of free fatty acids, triglycerides, and amino acids as substrates for foetal growth and development, which may be of considerable importance among obese pregnant women, who have demonstrated increased reliance on lipid metabolism [26]. Furthermore, increased consumption of fibre and a reduction in dietary saturated fats as reported in the LIMIT randomized trial may both be associated with improved maternal insulin resistance [28], and therefore have considerable potential to impact foetal growth and high infant birth weight [19 ,22 ]. In terms of ongoing benefits in child adiposity, observational studies have identified associations between modest changes in maternal dietary consumption of fatty acids and reduced adiposity as measured by both skin-fold thickness [29] and more invasive dual energy x-ray absorptiometry scanning [30]. Women in the Lifestyle Advice group of the LIMIT randomized trial reported an increase in their total physical activity (P ¼ 0.01), reflecting largely an increase in household activities, which was equivalent to approximately 15–20 min brisk walking on most days of the week, when compared with women who received Standard Care [24 ]. Physical activity is reported to decline as pregnancy advances &
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Modifying diet and physical activity to support pregnant women Dodd et al.
[31], an effect that is particularly evident among women who are overweight or obese [31,32]. Although physical activity declined over the course of pregnancy for all women in the LIMIT trial, the increase in physical activity following the provision of Lifestyle Advice was more pronounced among women who were obese [24 ]. &
THE SIGNIFICANCE OF THE LIMIT RANDOMIZED TRIAL The findings of the LIMIT randomized trial indicate that even in the absence of changes in gestational weight gain, modest changes to diet and physical activity patterns among women who are overweight or obese are effective in reducing the risk of a woman’s infant being born with high birth weight, without an increase in the risk of harm, including the risk of low birth weight. Observational data from the USA highlights the association between childhood obesity and high birth weight, in which one-third of individuals who were obese at 14 years of age were born with weight above 4 kg [33]. Antenatal interventions that are successful in reducing the risk of high birth weight infants therefore represent a public health strategy of considerable significance to tackle the global issue of increasing obesity, both in children and in adults [34]. To this end, the ongoing followup into childhood of infants whose mothers participated in the LIMIT randomized trial will provide robust evidence of any longer-term effects of maternal dietary manipulation during pregnancy on childhood adiposity and development. Although the economic implications associated with obesity in nonpregnant settings are reasonably well described, available information is more limited, not only in relation to pregnancy healthcare costs, but any longer-term healthcare savings that may be generated through a reduction in childhood obesity and its associated complications. A health economics analysis is currently being conducted utilizing data collected in parallel with the LIMIT randomized trial, to assess whether the costs of providing the antenatal intervention are mitigated by potential cost savings through the observed short-term improvements in neonatal health, with further potential for medium to longer-term impact on cost savings, including future risk of obesity.
AREAS TO STILL BE ADDRESSED An important step in the process to behaviour change requires women to both recognize the possible risks and consequences associated with overweight and obesity during pregnancy, and be
willing to change behaviour. Although the majority of women who participated in the LIMIT trial identified that they had an issue with their weight, they were less able to correctly identify their BMI. Specifically, only 25% of overweight and obese women correctly identified their BMI, with the majority of women significantly underestimating their size [35], a finding which has been reported by others [36,37]. Although there is extensive reporting in the literature of both complications for the woman and her infant associated with obesity during pregnancy, we, and others have reported that women’s knowledge of pregnancy complications is poor, particularly in relation to those potentially influencing the health of their infant [37–39]. Furthermore, we have reported that while pregnant women who are overweight or obese may acknowledge the benefits of healthy eating and physical activity, most indicate limited self-efficacy to initiate behaviour change [39]. Although many women ‘accept’ the inevitability of weight gain as a ‘normal’ part of pregnancy [40], they do identify a lack of information provided by healthcare professionals with regards to both weight gain and complications related to obesity, which is often considered to be inconsistent [40,41]. In contrast, information about diet and weight gain provided by family members is often more highly valued by women [41]. Uptake of participation in the LIMIT trial was relatively poor, with more than 60% of eligible women approached declining involvement [19 ]. Most commonly identified reasons for nonparticipation included a lack of interest, concern about an undue emphasis on diet during pregnancy, and concern with their body image [19 ]. In keeping with these themes are the reported barriers to behaviour change in pregnancy, which appear to be highly individualized. For many women the ‘label’ of being pregnant defined their unwillingness to make healthy changes, whereas for other women it represented a motivation for change [42]. Together, all of these findings highlight the need for further evaluation of the individual psychological characteristics, which are likely to increase success in achieving change [43], and provide an opportunity to provide more individualized intervention strategies. &
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CONCLUSION Maternal obesity is a significant contributor to poor health during pregnancy and is associated with an increased risk of complications for both the woman and her infant, including longer-term risk of childhood obesity. The findings of the LIMIT randomized trial indicate that through provision
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of a cost-effective antenatal dietary and lifestyle intervention, it is possible to improve diet and physical activity during pregnancy among women who are overweight or obese, and reduce significantly the risk of an infant being of high birth weight. This represents a strategy of considerable public health significance in tackling the ongoing and increasing problem of both childhood and adulthood obesity. Further attention is required in the identification of specific psychological characteristics of women to promote successful behaviour change, thereby increasing intervention uptake during pregnancy. Acknowledgements The authors thank all the women and babies who participated in the LIMIT study. Financial support and sponsorship The LIMIT Randomized Trial was funded by a four-year project grant from the National Health and Medical Research Council (NHMRC), Australia (ID 519240). J.M.D. is supported through an NHMRC Practitioner Fellowship (ID 627005). R.M.G. is supported through an NHMRC Early Career Fellowship (ID 1073514). We would also like to thank Early Nutrition for their funding support. Conflicts of interest There are no conflicts of interest.
REFERENCES AND RECOMMENDED READING Papers of particular interest, published within the annual period of review, have been highlighted as: & of special interest && of outstanding interest 1. World Health Organisation: Obesity Fact Sheet. http://www.who.int/media centre/factsheets/fs311/en/. [Accessed 3 March 2015] 2. Finucane MM, Stevens GA, Cowan MJ, et al. National, regional, and global trends in body-mass index since 1980: systematic analysis of health examination surveys and epidemiological studies with 960 country-years and 91 million participants. Lancet 2011; 377:557–567. 3. National Institute of Health and Clinical Excellence: Weight management before, during and after pregnancy. NICE Public Health Guidance 27. 2010. https://www.nice.org.uk/guidance/ph27. [Accessed 3 March 2015] 4. de Jersey SJ, Nicholson JM, Callaway LK, Daniels LA. A prospective study of pregnancy weight gain in Australian women. Aust N Z J Obstet Gynaecol 2012; 52:545–551. 5. Scheil W, Scott J, Catcheside B, et al. Pregnancy outcome in South Australia 2012. Adelaide: SA Health Pregnancy Outcome Unit, Government of South Australia; 2014. 6. Heslehurst N, Rankin J, Wilkinson JR, Summerbell CD. A nationally representative study of maternal obesity in England, UK: trends in incidence and demographic inequalities in 619 323 births, 1989–2007. Int J Obes (Lond) 2010; 34:420–428. 7. Dodd JM, Grivell RM, Nguyen A-M, et al. Maternal and perinatal health outcomes by body mass index category. Aust N Z J Obstet Gynaecol 2011; 51:136–140. 8. Fraser A, Tilling K, Macdonald-Wallis C, et al. Association of maternal weight gain in pregnancy with offspring obesity and metabolic and vascular traits in childhood. Circulation 2010; 121:2557–2564. 9. Tikellis G, Ponsonby AL, Wells JC, et al. Maternal and infant factors associated with neonatal adiposity: results from the Tasmanian Infant Health Survey (TIHS). Int J Obes 2012; 36:496–504.
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10. Godfrey KM, Inskip HM, Hanson MA. The long-term effects of prenatal development on growth and metabolism. Semin Reprod Med 2011; 29:257–265. 11. Wells JC, Haroun D, Levene D, et al. Prenatal and postnatal programming of body composition in obese children and adolescents: evidence from anthropometry, DXA and the 4-component model. Int J Obes 2011; 35:534–540. 12. Winter JD, Langenberg P, Krugman SD. Newborn adiposity by body mass index predicts childhood overweight. Clin Pediatr 2010; 49:866–870. 13. Institute of Medicine. Weight gain during pregnancy: reexamining the guidelines. Committee to Reexamine IOM Pregnancy Weight Guidelines. Washington, DC: National Research Council, USA; 2009. 14. Scott C, Andersen CT, Valdez N, et al. No global consensus: a cross-sectional survey of maternal weight policies. BMC Pregnancy Childbirth 2014; 14:167. 15. Dodd JM, Grivell RM, Crowther CA, Robinson JS. Antenatal interventions for overweight or obese pregnant women: a systematic review of randomised trials. BJ OG 2010; 117:1316–1326. 16. Oteng-Ntim E, Varma R, Croker H, et al. Lifestyle interventions for overweight and obese pregnant women to improve pregnancy outcome: systematic review and meta-analysis. BMC Med 2012; 10:47. 17. Thangaratinam S, Rogozinska E, Jolly K, et al. Effects of interventions in pregnancy on maternal weight and obstetric outcomes: meta-analysis of randomised evidence. BMJ 2012; 344:e2088. 18. Dodd JM, Turnbull DA, McPhee AJ, et al. Limiting weight gain in overweight and obese women during pregnancy to improve health outcomes: the LIMIT randomised controlled trial. BMC Pregnancy Childbirth 2011; 11:79. 19. Dodd JM, Turnbull DA, McPhee AJ, et al. Antenatal lifestyle advice for women & who are overweight or obese: the LIMIT randomised trial. BMJ 2014; 348:g1285. Detailed presentation of maternal and neonatal health outcomes following the LIMIT randomized trial intervention. 20. Australian Guide to Healthy Eating. http://www.health.gov.au/internet/pub lications/publishing.nsf/Content/nhsc-guidelinesaus-guide-healthy-eating. [Accessed 3 March 2015] 21. South Australian Perinatal Practice Guidelines: Normal pregnancy, labour and puerperium. http://www.sahealth.sa.gov.au/wps/wcm/connect/26cf8d004 ee52a4fa536add150ce4f37/Normal+pregnancy+labour+and+puerperium+ management_May2014.pdf?MOD=AJPERES&CACHEID=26cf8d004ee52 a4fa536add150ce4f37. [Accessed 3 March 2015] 22. Dodd JM, McPhee AJ, Turnbull DA, et al. The effect of antenatal lifestyle advice & for women who are overweight or obese on neonatal health: the LIMIT randomised trial. BMC Med 2014; 12:163; http://www.biomedcentral. com/1741-7015/12/163. [Accessed 13 January 2015] Detailed presentation of neonatal health outcomes following the LIMIT randomized trial intervention. 23. Norris SL, Zhang X, Avenell A, et al. Long-term nonpharmacological weight loss interventions for adults with prediabetes (Review). Cochrane Database Syst Rev 2005; (3):CD005270. 24. Dodd JM, Cramp CS, Sui Z, et al. Effects of antenatal lifestyle advice for & women who are overweight or obese on maternal diet and physical activity: the LIMIT randomised trial. BMC Med 2014; 12:161. http://www.biomed central.com/1741-7015/12/161. [Accessed 6 January 2015] Detailed presentation of maternal dietary and physical activity patterns following the LIMIT randomized trial intervention. 25. Guelinckx I, Devlieger R, Mullie P, Vansant G. Effect of a lifestyle intervention on dietary habits, physical activity, and gestational weight gain in obese pregnant women: a randomized controlled trial. Am J Clin Nutr 2010; 91:373–380. 26. Poston L, Briley AL, Barr S, et al. Developing a complex intervention for diet and activity behaviour change in obese pregnant women (the UPBEAT trial); assessment of behavioural change and process evaluation in a pilot randomised controlled trial. BMC Pregnancy Childbirth 2013; 13:148. 27. Okereke NC, Huston-Presley L, Amini SB, et al. Longitudinal changes in energy expenditure and body composition in obese women with normal and impaired glucose tolerance. Am J Physiol Endocrinol Metab 2004; 287:E472–E479. 28. Ley SH, Hanley AJ, Retnakaran R, et al. Effect of macronutrient intake during the second trimester on glucose metabolism later in pregnancy. Am J Clin Nutr 2011; 94:1232–1240. 29. Donahue SM, Rifas-Shiman SL, Gold DR, et al. Prenatal fatty acid status and child adiposity at age 3 y: results from a US pregnancy cohort. Am J Clin Nutr 2011; 93:780–788. 30. Moon RJ, Harvey NC, Robinson SM, et al. Maternal plasma polyunsaturated fatty acid status in late pregnancy is associated with offspring body composition in childhood. J Clin Endocrinol Metab 2013; 98:299–307. 31. Gaston A, Cramp A. Exercise during pregnancy: a review of patterns and determinants. J Sci Med Sport 2011; 14:299–305. 32. Davis JN, Hodges VA, Gillham MB. Physical activity compliance: differences between overweight/obese and normal-weight adults. Obesity (Silver Spring) 2006; 14:2259–2265. 33. Cunningham SA, Kramer MR, Narayan KM. Incidence of childhood obesity in the United States. N Engl J Med 2014; 370:403–411. 34. Poston L. Healthy eating in pregnancy – always a good idea, now with more supporting evidence. BMJ 2014; 348:g1739. 35. Sui Z, Turnbull D, Dodd JM. Effect of body image on gestational weight gain in overweight and obese women. Women Birth 2013; 26:267–272.
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Modifying diet and physical activity to support pregnant women Dodd et al. 36. Gaudet LM, Gruslin A, Magee LA. Weight in pregnancy and its implications: what women report. J Obstet Gynaecol Can 2011; 33:227–234. 37. Shub A, Huning EY, Campbell KJ, McCarthy EA. Pregnant women’s knowledge of weight, weight gain, complications of obesity and weight management strategies in pregnancy. BMC Res Notes 2013; 6:278. 38. Nitert MD, Foxcroft KF, Lust K, et al. Overweight and obesity knowledge prior to pregnancy: a survey study. BMC Pregnancy Childbirth 2011; 11:96. 39. Sui Z, Turnbull DA, Dodd JM. Overweight and obese women’s perceptions about making healthy change during pregnancy: a mixed method study. Matern Child Health J 2012; 17:1887.
40. Smith D, Lavender T. The maternity experience for women with a body mass index 30 kg/m2: a meta-synthesis. BJOG 2011; 118:779–789. 41. Tovar A, Chasan-Taber L, Bermudez OI, et al. Knowledge, attitudes, and beliefs regarding weight gain during pregnancy among Hispanic women. Matern Child Health J 2010; 14:938–949. 42. Sui Z, Turnbull D, Dodd JM. Enablers and barriers to making healthy change during pregnancy in overweight and obese women. Australas Med J 2013; 6:565–577. 43. Gardner B, Wardle J, Poston L, Croker H. Changing diet and physical activity to reduce gestational weight gain: a meta-analysis. Obes Rev 2011; 12:e602– e620.
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Modifying diet and physical activity to support pregnant women who are overweight or obese Jodie M. Dodd a,b, Cecelia M. O’Brien a,b, and Rosalie M. Grivell a,b
Purpose of review Overweight and obesity represent a significant health burden during pregnancy, placing women and their infants at increased risk of adverse health outcomes. Although there is considerable observational literature describing the effect of gestational weight gain in pregnancy, research efforts have focused on limiting gestational weight gain among pregnant women who are overweight or obese, with limited reporting of clinical outcomes. Recent findings The LIMIT randomized trial recruited 2212 pregnant women with a BMI at least 25 kg/m2. Providing an antenatal dietary and lifestyle intervention was associated with significant improvements in maternal diet and physical activity patterns, and a significant reduction in the risk of infants being born with high birth weight. Summary The findings of the LIMIT randomized trial provide the first evidence that changes in maternal diet and physical activity during pregnancy can reduce the risk of high infant birth weight among women who are overweight or obese, and from a public health perspective, may represent a significant strategy to tackle the increasing problem of childhood and adulthood obesity. Keywords dietary and lifestyle intervention, maternal and infant health outcomes, overweight and obesity, randomized trial, review
INTRODUCTION The World Health Organisation defines individuals as overweight if their BMI is between 25.0 and 29.9 kg/m2, and obese if their BMI is greater than or equal to 30.0 kg/m2 [1]. Worldwide, obesity represents a major health concern, with estimates suggesting approximately 1.5 billion adults are obese [2]. Obesity in pregnancy is increasingly common, and in Australia, as in other developed nations, more than 50% of women are overweight or obese on entering pregnancy [3–5]. Maternal obesity is recognized as the single largest contributor to compromised health during pregnancy [6]. Indeed, maternal obesity is associated with an increased risk of virtually all pregnancy complications, including preeclampsia, gestational diabetes, need for induction of labour, and caesarean birth, in addition to adverse outcomes for the infant, including perinatal death [7]. Furthermore, there is recognition of a link between maternal obesity and a longer-term child health legacy. There are well described associations between maternal overweight and obesity, and infant birth weight above www.co-clinicalnutrition.com
4 kg [7], which in turn, is associated with a greater risk of both child and adult obesity [8–12].
LIMITING GESTATIONAL WEIGHT GAIN There is a considerable observational literature describing the effect of gestational weight gain in pregnancy, with recommendations by maternal BMI category presented by the US based Institute of Medicine suggesting that women who are overweight gain between 7.0 and 11.5 kg, and women who are obese between 5.0 and 9.0 kg [13]. Although
a
School of Paediatrics and Reproductive Health, Robinson Research Institute, University of Adelaide, Adelaide and bDepartment of Perinatal Medicine, Women’s and Babies Division, Women’s and Children’s Hospital, North Adelaide, Australia Correspondence to Professor Jodie M. Dodd, University of Adelaide, Women’s and Children’s Hospital, 72 King William Road, North Adelaide, South Australia 5006, Australia. Tel: +61 8 8161 7619; fax: +61 8 8161 7652; e-mail: [email protected] Curr Opin Clin Nutr Metab Care 2015, 18:318–323 DOI:10.1097/MCO.0000000000000170 Volume 18 Number 3 May 2015
Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
Modifying diet and physical activity to support pregnant women Dodd et al.
KEY POINTS
Advice group) delivered across their pregnancy or to receive standard antenatal care (Standard Care group) [19 ]. The dietary and lifestyle intervention included a combination of dietary, exercise, and behavioural strategies, delivered by a research dietician and trained research assistants [18]. Specifically, dietary information was consistent with the Australian Guide to Healthy Eating [20], in which women were encouraged to reduce their intake of foods high in refined carbohydrates and saturated fats, whereas increasing their intake of fibre, through the consumption of two servings of fruit, five servings of vegetables, and three servings of dairy each day. Physical activity advice focussed on encouraging women to increase their daily walking and incidental activity. In consultation with the research dietician, each woman was encouraged to identify and set achievable goals for dietary and physical activity change, supported to make these changes to their lifestyle, and to self-monitor their progress. Furthermore, each woman was encouraged to identify potential barriers to the implementation of their goals and, using these perceived barriers, were assisted to both problem solve and develop individualized facilitative strategies. At each subsequent contact with the woman, this information was reinforced. The women allocated to receive Standard Care continued their pregnancy care in accordance with statewide and local hospital guidelines, who did not include the provision of dietary or physical activity advice, or information about weight gain during pregnancy [21]. &
Fifty percent of women enter pregnancy with a BMI at least 25 kg/m2, with maternal obesity recognized as the single largest contributor to compromised health during pregnancy. Providing dietary and lifestyle advice to pregnant women who are overweight or obese is associated with a significant 18% relative risk reduction in the chance of an infant with birth weight above 4 kg. Providing dietary and lifestyle advice to pregnant women who are overweight or obese is associated with significant improvements in maternal diet and physical activity patterns. The findings of the LIMIT randomized trial represent a strategy of considerable public health significance in tackling the ongoing and increasing problem of both childhood and adulthood obesity.
many countries globally have adopted these recommendations, there appears to be a lack of international consensus as to the most appropriate content of guidelines addressing maternal gestational weight gain [14], reflecting the lack of a high-quality evidence base. In an attempt to improve the available evidence relating to optimal gestational weight gain, there has been a considerable research focus on evaluating interventions for women who are overweight or obese, with several published systematic reviews and meta-analyses of randomized trials [15–17]. Although the majority of included trials are of relatively small sample size, it would appear from these meta-analyses that providing an antenatal dietary and/or lifestyle intervention for overweight or obese pregnant women is somewhat effective in limiting gestational weight gain [15–17]. Importantly, however, studies conducted to date have largely ignored reporting of clinical maternal and infant outcomes [15–17].
MATERNAL AND INFANT CLINICAL OUTCOMES FROM THE LIMIT RANDOMIZED TRIAL A total of 2212 women participated in the LIMIT randomized trial, of whom 42% of women were overweight, and 58% obese, with the median BMI of the cohort 31.1 kg/m2 [19 ]. For infants born to women who received Lifestyle Advice, there was a significant 18% relative risk reduction in the chance of birth weight above 4.0 kg, when compared with infants born to women who received Standard Care (P ¼ 0.04) [19 ]. Furthermore, there was a significant 41% relative risk reduction in the chance of birth weight above 4.5 kg (P ¼ 0.04), with no increase in the risk of low infant birth weight, for infants born following Lifestyle Advice, when compared with infants born to women who received Standard Care [22 ]. Despite a lack of difference in the use of either antenatal corticosteroids or mean gestational age at birth, infants born to women who received Lifestyle &
METHODOLOGY OF THE LIMIT RANDOMIZED TRIAL In view of the limitations in the literature describing the effects of antenatal dietary and lifestyle interventions on maternal, foetal, neonatal, and infant outcomes, the LIMIT randomized trial was conducted [18], involving 2212 women with a singleton pregnancy and BMI at least 25 kg/m2 [19 ]. Using a computer-generated schedule and central telephone randomization service, women were randomized after providing informed consent either to receive a comprehensive lifestyle intervention (Lifestyle &
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Advice were 53% less likely to be diagnosed with moderate or severe respiratory distress syndrome (P ¼ 0.02) [22 ]. Although the increased diagnosis of respiratory distress syndrome was not associated with a statistically significant difference in the chance of admission to the neonatal nursery, overall, infants born following Lifestyle Advice had a shorter hospital length of stay (P ¼ 0.006) [22 ]. Although there were significant improvements in infant health outcomes, there were no statistically significant differences identified between the treatment groups for any of the maternal antenatal, labour, or birth outcomes which have been previously identified to be increased among women who are overweight or obese [19 ]. &
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THE EFFECT OF THE LIMIT INTERVENTION ON GESTATIONAL WEIGHT GAIN The mean gestational weight gain of women who participated in the LIMIT randomized trial was 9.4 kg, and did not differ significantly between those women who received Lifestyle Advice and those receiving Standard Care [19 ]. When considering the Institute of Medicine weight gain recommendations by early pregnancy BMI category, approximately 42% of all women were considered to have excessive weight gain, with 33% of women gaining weight within the target range [19 ]. The proportion of women within each weight gain range did not differ significantly between the two treatment groups [19 ]. These findings are in contrast to the effect on gestational weight gain reported in systematic reviews [15–17]. However, the intensity of the intervention provided in the LIMIT randomized trial involving three face-to-face sessions and three telephone contacts, is consistent with that reported by the individual included studies, the majority providing between three and six intervention sessions [15–17]. At the time of designing the trial, it was not considered practical to increase the intensity of the intervention further, either from the perspective of a healthcare setting with limited resources or with respect to individual compliance. The issue of compliance with the intervention is particularly relevant, with only 87% of women participating in the LIMIT trial attending their first dietary session, and falling further to 77% for their second dietary session [19 ]. Our findings are consistent with the available literature relating to weight loss interventions in nonpregnant individuals, which indicates that while increasing the number of intervention sessions increases effect, there are issues in maintaining ongoing compliance [23]. &
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THE EFFECT OF THE LIMIT INTERVENTION ON MATERNAL DIET AND PHYSICAL ACTIVITY Although the provision of Lifestyle Advice was not associated with differences in gestational weight gain or total energy intake during pregnancy [19 ], women were successful in making significant improvements to both their diet and physical activity patterns [24 ]. Women who received Lifestyle Advice significantly increased the number of servings per day of fruits and vegetables, and consequently their daily fibre intake, when compared with women who received Standard Care (P < 0.05 for all) [24 ]. Furthermore, women provided with Lifestyle Advice demonstrated a significant reduction in the percentage of their energy intake which was derived from saturated fats (P < 0.05) [24 ]. The healthy eating index, as an assessment of overall dietary quality was significantly improved at both 28 weeks (P < 0.0001) and 36 weeks (P < 0.0001) gestation among women receiving Lifestyle Advice [24 ]. Similar findings of improved dietary intake have been reported in smaller randomized trials involving overweight and obese pregnant women have been described, particularly reduced dietary consumption of saturated fats [25–27], some of which have occurred in the absence of an effect on either reported total energy intake or gestational weight gain [25]. From a mechanistic perspective, there is increasing recognition of the role of free fatty acids, triglycerides, and amino acids as substrates for foetal growth and development, which may be of considerable importance among obese pregnant women, who have demonstrated increased reliance on lipid metabolism [26]. Furthermore, increased consumption of fibre and a reduction in dietary saturated fats as reported in the LIMIT randomized trial may both be associated with improved maternal insulin resistance [28], and therefore have considerable potential to impact foetal growth and high infant birth weight [19 ,22 ]. In terms of ongoing benefits in child adiposity, observational studies have identified associations between modest changes in maternal dietary consumption of fatty acids and reduced adiposity as measured by both skin-fold thickness [29] and more invasive dual energy x-ray absorptiometry scanning [30]. Women in the Lifestyle Advice group of the LIMIT randomized trial reported an increase in their total physical activity (P ¼ 0.01), reflecting largely an increase in household activities, which was equivalent to approximately 15–20 min brisk walking on most days of the week, when compared with women who received Standard Care [24 ]. Physical activity is reported to decline as pregnancy advances &
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[31], an effect that is particularly evident among women who are overweight or obese [31,32]. Although physical activity declined over the course of pregnancy for all women in the LIMIT trial, the increase in physical activity following the provision of Lifestyle Advice was more pronounced among women who were obese [24 ]. &
THE SIGNIFICANCE OF THE LIMIT RANDOMIZED TRIAL The findings of the LIMIT randomized trial indicate that even in the absence of changes in gestational weight gain, modest changes to diet and physical activity patterns among women who are overweight or obese are effective in reducing the risk of a woman’s infant being born with high birth weight, without an increase in the risk of harm, including the risk of low birth weight. Observational data from the USA highlights the association between childhood obesity and high birth weight, in which one-third of individuals who were obese at 14 years of age were born with weight above 4 kg [33]. Antenatal interventions that are successful in reducing the risk of high birth weight infants therefore represent a public health strategy of considerable significance to tackle the global issue of increasing obesity, both in children and in adults [34]. To this end, the ongoing followup into childhood of infants whose mothers participated in the LIMIT randomized trial will provide robust evidence of any longer-term effects of maternal dietary manipulation during pregnancy on childhood adiposity and development. Although the economic implications associated with obesity in nonpregnant settings are reasonably well described, available information is more limited, not only in relation to pregnancy healthcare costs, but any longer-term healthcare savings that may be generated through a reduction in childhood obesity and its associated complications. A health economics analysis is currently being conducted utilizing data collected in parallel with the LIMIT randomized trial, to assess whether the costs of providing the antenatal intervention are mitigated by potential cost savings through the observed short-term improvements in neonatal health, with further potential for medium to longer-term impact on cost savings, including future risk of obesity.
AREAS TO STILL BE ADDRESSED An important step in the process to behaviour change requires women to both recognize the possible risks and consequences associated with overweight and obesity during pregnancy, and be
willing to change behaviour. Although the majority of women who participated in the LIMIT trial identified that they had an issue with their weight, they were less able to correctly identify their BMI. Specifically, only 25% of overweight and obese women correctly identified their BMI, with the majority of women significantly underestimating their size [35], a finding which has been reported by others [36,37]. Although there is extensive reporting in the literature of both complications for the woman and her infant associated with obesity during pregnancy, we, and others have reported that women’s knowledge of pregnancy complications is poor, particularly in relation to those potentially influencing the health of their infant [37–39]. Furthermore, we have reported that while pregnant women who are overweight or obese may acknowledge the benefits of healthy eating and physical activity, most indicate limited self-efficacy to initiate behaviour change [39]. Although many women ‘accept’ the inevitability of weight gain as a ‘normal’ part of pregnancy [40], they do identify a lack of information provided by healthcare professionals with regards to both weight gain and complications related to obesity, which is often considered to be inconsistent [40,41]. In contrast, information about diet and weight gain provided by family members is often more highly valued by women [41]. Uptake of participation in the LIMIT trial was relatively poor, with more than 60% of eligible women approached declining involvement [19 ]. Most commonly identified reasons for nonparticipation included a lack of interest, concern about an undue emphasis on diet during pregnancy, and concern with their body image [19 ]. In keeping with these themes are the reported barriers to behaviour change in pregnancy, which appear to be highly individualized. For many women the ‘label’ of being pregnant defined their unwillingness to make healthy changes, whereas for other women it represented a motivation for change [42]. Together, all of these findings highlight the need for further evaluation of the individual psychological characteristics, which are likely to increase success in achieving change [43], and provide an opportunity to provide more individualized intervention strategies. &
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CONCLUSION Maternal obesity is a significant contributor to poor health during pregnancy and is associated with an increased risk of complications for both the woman and her infant, including longer-term risk of childhood obesity. The findings of the LIMIT randomized trial indicate that through provision
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of a cost-effective antenatal dietary and lifestyle intervention, it is possible to improve diet and physical activity during pregnancy among women who are overweight or obese, and reduce significantly the risk of an infant being of high birth weight. This represents a strategy of considerable public health significance in tackling the ongoing and increasing problem of both childhood and adulthood obesity. Further attention is required in the identification of specific psychological characteristics of women to promote successful behaviour change, thereby increasing intervention uptake during pregnancy. Acknowledgements The authors thank all the women and babies who participated in the LIMIT study. Financial support and sponsorship The LIMIT Randomized Trial was funded by a four-year project grant from the National Health and Medical Research Council (NHMRC), Australia (ID 519240). J.M.D. is supported through an NHMRC Practitioner Fellowship (ID 627005). R.M.G. is supported through an NHMRC Early Career Fellowship (ID 1073514). We would also like to thank Early Nutrition for their funding support. Conflicts of interest There are no conflicts of interest.
REFERENCES AND RECOMMENDED READING Papers of particular interest, published within the annual period of review, have been highlighted as: & of special interest && of outstanding interest 1. World Health Organisation: Obesity Fact Sheet. http://www.who.int/media centre/factsheets/fs311/en/. [Accessed 3 March 2015] 2. Finucane MM, Stevens GA, Cowan MJ, et al. National, regional, and global trends in body-mass index since 1980: systematic analysis of health examination surveys and epidemiological studies with 960 country-years and 91 million participants. Lancet 2011; 377:557–567. 3. National Institute of Health and Clinical Excellence: Weight management before, during and after pregnancy. NICE Public Health Guidance 27. 2010. https://www.nice.org.uk/guidance/ph27. [Accessed 3 March 2015] 4. de Jersey SJ, Nicholson JM, Callaway LK, Daniels LA. A prospective study of pregnancy weight gain in Australian women. Aust N Z J Obstet Gynaecol 2012; 52:545–551. 5. Scheil W, Scott J, Catcheside B, et al. Pregnancy outcome in South Australia 2012. Adelaide: SA Health Pregnancy Outcome Unit, Government of South Australia; 2014. 6. Heslehurst N, Rankin J, Wilkinson JR, Summerbell CD. A nationally representative study of maternal obesity in England, UK: trends in incidence and demographic inequalities in 619 323 births, 1989–2007. Int J Obes (Lond) 2010; 34:420–428. 7. Dodd JM, Grivell RM, Nguyen A-M, et al. Maternal and perinatal health outcomes by body mass index category. Aust N Z J Obstet Gynaecol 2011; 51:136–140. 8. Fraser A, Tilling K, Macdonald-Wallis C, et al. Association of maternal weight gain in pregnancy with offspring obesity and metabolic and vascular traits in childhood. Circulation 2010; 121:2557–2564. 9. Tikellis G, Ponsonby AL, Wells JC, et al. Maternal and infant factors associated with neonatal adiposity: results from the Tasmanian Infant Health Survey (TIHS). Int J Obes 2012; 36:496–504.
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10. Godfrey KM, Inskip HM, Hanson MA. The long-term effects of prenatal development on growth and metabolism. Semin Reprod Med 2011; 29:257–265. 11. Wells JC, Haroun D, Levene D, et al. Prenatal and postnatal programming of body composition in obese children and adolescents: evidence from anthropometry, DXA and the 4-component model. Int J Obes 2011; 35:534–540. 12. Winter JD, Langenberg P, Krugman SD. Newborn adiposity by body mass index predicts childhood overweight. Clin Pediatr 2010; 49:866–870. 13. Institute of Medicine. Weight gain during pregnancy: reexamining the guidelines. Committee to Reexamine IOM Pregnancy Weight Guidelines. Washington, DC: National Research Council, USA; 2009. 14. Scott C, Andersen CT, Valdez N, et al. No global consensus: a cross-sectional survey of maternal weight policies. BMC Pregnancy Childbirth 2014; 14:167. 15. Dodd JM, Grivell RM, Crowther CA, Robinson JS. Antenatal interventions for overweight or obese pregnant women: a systematic review of randomised trials. BJ OG 2010; 117:1316–1326. 16. Oteng-Ntim E, Varma R, Croker H, et al. Lifestyle interventions for overweight and obese pregnant women to improve pregnancy outcome: systematic review and meta-analysis. BMC Med 2012; 10:47. 17. Thangaratinam S, Rogozinska E, Jolly K, et al. Effects of interventions in pregnancy on maternal weight and obstetric outcomes: meta-analysis of randomised evidence. BMJ 2012; 344:e2088. 18. Dodd JM, Turnbull DA, McPhee AJ, et al. Limiting weight gain in overweight and obese women during pregnancy to improve health outcomes: the LIMIT randomised controlled trial. BMC Pregnancy Childbirth 2011; 11:79. 19. Dodd JM, Turnbull DA, McPhee AJ, et al. Antenatal lifestyle advice for women & who are overweight or obese: the LIMIT randomised trial. BMJ 2014; 348:g1285. Detailed presentation of maternal and neonatal health outcomes following the LIMIT randomized trial intervention. 20. Australian Guide to Healthy Eating. http://www.health.gov.au/internet/pub lications/publishing.nsf/Content/nhsc-guidelinesaus-guide-healthy-eating. [Accessed 3 March 2015] 21. South Australian Perinatal Practice Guidelines: Normal pregnancy, labour and puerperium. http://www.sahealth.sa.gov.au/wps/wcm/connect/26cf8d004 ee52a4fa536add150ce4f37/Normal+pregnancy+labour+and+puerperium+ management_May2014.pdf?MOD=AJPERES&CACHEID=26cf8d004ee52 a4fa536add150ce4f37. [Accessed 3 March 2015] 22. Dodd JM, McPhee AJ, Turnbull DA, et al. The effect of antenatal lifestyle advice & for women who are overweight or obese on neonatal health: the LIMIT randomised trial. BMC Med 2014; 12:163; http://www.biomedcentral. com/1741-7015/12/163. [Accessed 13 January 2015] Detailed presentation of neonatal health outcomes following the LIMIT randomized trial intervention. 23. Norris SL, Zhang X, Avenell A, et al. Long-term nonpharmacological weight loss interventions for adults with prediabetes (Review). Cochrane Database Syst Rev 2005; (3):CD005270. 24. Dodd JM, Cramp CS, Sui Z, et al. Effects of antenatal lifestyle advice for & women who are overweight or obese on maternal diet and physical activity: the LIMIT randomised trial. BMC Med 2014; 12:161. http://www.biomed central.com/1741-7015/12/161. [Accessed 6 January 2015] Detailed presentation of maternal dietary and physical activity patterns following the LIMIT randomized trial intervention. 25. Guelinckx I, Devlieger R, Mullie P, Vansant G. Effect of a lifestyle intervention on dietary habits, physical activity, and gestational weight gain in obese pregnant women: a randomized controlled trial. Am J Clin Nutr 2010; 91:373–380. 26. Poston L, Briley AL, Barr S, et al. Developing a complex intervention for diet and activity behaviour change in obese pregnant women (the UPBEAT trial); assessment of behavioural change and process evaluation in a pilot randomised controlled trial. BMC Pregnancy Childbirth 2013; 13:148. 27. Okereke NC, Huston-Presley L, Amini SB, et al. Longitudinal changes in energy expenditure and body composition in obese women with normal and impaired glucose tolerance. Am J Physiol Endocrinol Metab 2004; 287:E472–E479. 28. Ley SH, Hanley AJ, Retnakaran R, et al. Effect of macronutrient intake during the second trimester on glucose metabolism later in pregnancy. Am J Clin Nutr 2011; 94:1232–1240. 29. Donahue SM, Rifas-Shiman SL, Gold DR, et al. Prenatal fatty acid status and child adiposity at age 3 y: results from a US pregnancy cohort. Am J Clin Nutr 2011; 93:780–788. 30. Moon RJ, Harvey NC, Robinson SM, et al. Maternal plasma polyunsaturated fatty acid status in late pregnancy is associated with offspring body composition in childhood. J Clin Endocrinol Metab 2013; 98:299–307. 31. Gaston A, Cramp A. Exercise during pregnancy: a review of patterns and determinants. J Sci Med Sport 2011; 14:299–305. 32. Davis JN, Hodges VA, Gillham MB. Physical activity compliance: differences between overweight/obese and normal-weight adults. Obesity (Silver Spring) 2006; 14:2259–2265. 33. Cunningham SA, Kramer MR, Narayan KM. Incidence of childhood obesity in the United States. N Engl J Med 2014; 370:403–411. 34. Poston L. Healthy eating in pregnancy – always a good idea, now with more supporting evidence. BMJ 2014; 348:g1739. 35. Sui Z, Turnbull D, Dodd JM. Effect of body image on gestational weight gain in overweight and obese women. Women Birth 2013; 26:267–272.
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Modifying diet and physical activity to support pregnant women Dodd et al. 36. Gaudet LM, Gruslin A, Magee LA. Weight in pregnancy and its implications: what women report. J Obstet Gynaecol Can 2011; 33:227–234. 37. Shub A, Huning EY, Campbell KJ, McCarthy EA. Pregnant women’s knowledge of weight, weight gain, complications of obesity and weight management strategies in pregnancy. BMC Res Notes 2013; 6:278. 38. Nitert MD, Foxcroft KF, Lust K, et al. Overweight and obesity knowledge prior to pregnancy: a survey study. BMC Pregnancy Childbirth 2011; 11:96. 39. Sui Z, Turnbull DA, Dodd JM. Overweight and obese women’s perceptions about making healthy change during pregnancy: a mixed method study. Matern Child Health J 2012; 17:1887.
40. Smith D, Lavender T. The maternity experience for women with a body mass index 30 kg/m2: a meta-synthesis. BJOG 2011; 118:779–789. 41. Tovar A, Chasan-Taber L, Bermudez OI, et al. Knowledge, attitudes, and beliefs regarding weight gain during pregnancy among Hispanic women. Matern Child Health J 2010; 14:938–949. 42. Sui Z, Turnbull D, Dodd JM. Enablers and barriers to making healthy change during pregnancy in overweight and obese women. Australas Med J 2013; 6:565–577. 43. Gardner B, Wardle J, Poston L, Croker H. Changing diet and physical activity to reduce gestational weight gain: a meta-analysis. Obes Rev 2011; 12:e602– e620.
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