Prevention Randomised controlled trial

Lifestyle interventions in obese and overweight pregnant women do not reduce the risk of large-forgestational age babies 10.1136/eb-2014-110007

Shakila Thangaratinam Queen Mary, University of London, London, UK Correspondence to: Professor Shakila Thangaratinam, Women’s Health Research Unit, Centre for Primary Care and Public Health, Blizard Institute, Barts and The London School of Medicine and Dentistry, Yvonne Carter Building, 58 Turner Street, Whitechapel, London E1 2AB, UK; [email protected]

Commentary on: Dodd JM, Turnbull D, McPhee AJ et al. Antenatal lifestyle advice for women who are overweight or obese: LIMIT randomised trial. BMJ 2014;348:g1285.

Context Pregnant women who are overweight or obese and undergo excessive gestational weight gain are at risk of maternal and fetal complications.1 Diet-based and physical activity-based interventions may improve pregnancy outcomes. Any reduction in the risk of high infant birth weight may lower rates of new-born complications and childhood obesity.2

Commentary Around a quarter of the participants in the intervention arm did not attend all the planned sessions with the dietician, and this may have influenced the results. The baseline diet and physical activity of the participants and any change in these with the intervention were not known. It is difficult to assess the impact of non-compliance with the intervention on the important outcomes. The predominance of socially disadvantaged white mothers in the study limited the external validity of the findings. The LIMIT study is the largest randomised trial on lifestyle interventions in pregnancy. The results are consistent with those of the recent meta-analysis, which showed that diet and lifestyle advice in pregnancy had no effect on the birth weight or the incidence of large-for-gestational age babies.3 Previous trials on diet and lifestyle in obese and high-risk women did not observe reduction in the incidence of large-for-gestational age fetuses, despite beneficial effects on gestational weight gain.4–6 The observed effect of the intervention in reducing high birth weight over 4 kg needs to be confirmed in further trials. The differential effects of the intervention in various groups of women based on age, ethnicity, socioeconomic status and BMI class for clinically relevant outcomes is not known. A primary trial to answer these questions requires a large sample size with associated burden of costs and time, and aggregate meta-analysis does not have patient-level information and the treatmentcovariate interactions are rarely reported in sufficient detail. A meta-analysis of individual participant data (IPD), where the raw patient-level data are obtained and synthesised across trials, such as the International Weight Management in Pregnancy (i-WIP) IPD Collaborative Project can address the above questions.7 Antenatal advice on diet and physical activity does not influence fetal-weight-related outcomes in obese women. Healthcare professionals need to be aware of the limitations of these interventions, and their low compliance rates, when counselling pregnant women. Competing interests Chief Investigator of i-WIP project.

Methods The LIMIT trial evaluated whether antenatal lifestyle interventions in overweight (body mass index (BMI) 25–29.9 kg/m2) and obese (BMI≥30 kg/m2) women improved fetal and maternal outcomes. Eligible women were recruited at between 10 and 20 weeks’ gestation from three hospitals in Australia. Participants were randomised to receive a comprehensive lifestyle intervention based on diet, physical activity and behavioural strategies (intervention group), or standard antenatal care (control group). The outcome assessors were blinded to the allocation and the sample size was calculated appropriately. The lifestyle advice promoted intake of a balanced healthy diet and encouraged physical activity such as walking. The intervention was delivered in regular intervals by dieticians or trained research assistants. The control group did not receive any routine advice on diet or physical activity. The primary outcome was the incidence of large-for-gestational age baby, defined as birth weight ≥90th centile for gestation and sex.

Findings The trial recruited 2212 women and observed no significant difference in the rates of large-for-gestational age infants (relative risk (RR)=0.90, 95% CI 0.77 to 1.07) between the two groups. Fewer babies in the intervention group had a birth weight of more than 4 kg (RR=0.82, 95% 0.68 to 0.99), compared with the control group. The intervention appeared to have no effect on other maternal and fetal outcomes, including gestational weight gain.

References 1. Ramachendran J, Bradford J, McLean J. Maternal obesity and pregnancy complications: a review. Aust N Z J Obstet Gynaecol 2008;48:228–45. 2. Boney CM, Verma A, Tucker R, et al. Metabolic syndrome in childhood: association with birth weight, maternal obesity, and gestational diabetes mellitus. Pediatrics 2005;115:e290–6. 3. 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. 4. Walsh JM, McGowan CA, Mahony R, et al. Low glycaemic index diet in pregnancy to prevent macrosomia (ROLO study): randomised control trial. BMJ 2012;345:e5605. 5. Wolff S, Legarth J, Vangsgaard K, et al. A randomized trial of the effects of dietary counseling on gestational weight gain and glucose metabolism in obese pregnant women. Int J Obes 2008;32:495–501. 6. Vinter CA, Jensen DM, Ovesen P, et al. The LiP (Lifestyle in Pregnancy) study: a randomized controlled trial of lifestyle intervention in 360 obese pregnant women. Diabetes Care 2011;34:2502–7. 7. Thangaratinam S, Coomarasamy A, Jit M, et al. Effects of weight management interventions on maternal and fetal outcomes in pregnancy: individual patient data (IPD) meta analysis of randomised trials and model based economic evaluation. Health Technol Assess. [Research in progress]. http://www.nets.nihr.ac.uk/projects/ hta/120150 (accessed 19 Apr 2014).

Evid Based Med October 2014 | volume 19 | number 5 |

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Lifestyle interventions in obese and overweight pregnant women do not reduce the risk of large-for-gestational age babies.

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