Clinical Nutrition xxx (2014) 1e5
Contents lists available at ScienceDirect
Clinical Nutrition journal homepage: http://www.elsevier.com/locate/clnu
Association between gestational weight gain according to prepregnancy body mass index and short postpartum weight retention in postpartum women Defu Ma a, Ignatius M.Y. Szeto b, Kai Yu b, Yibing Ning b, Wenjun Li c, Junkuan Wang b, Yingdong Zheng a, Yumei Zhang a, **, Peiyu Wang a, * a b c
School of Public Health, Peking University Health Science Center, Beijing, China Nestlé Research Center, Beijing, China Nestlé Nutrition Institute of China, China
a r t i c l e i n f o
s u m m a r y
Article history: Received 6 February 2014 Accepted 15 April 2014
Background & aims: This study aims to assess the relationship among prepregnancy body mass index, gestational weight gain, and postpartum weight retention, and to clarify the predictors of the amount of weight retained by Chinese women after pregnancy. Methods: The multistage stratified random sampling was used in the cross-sectional study. Results: The subjects included 1643 women. Mean gestational weight gain was 15.9 kg and mean postpartum weight retention was 5.1 kg. 43.2% of women gained excessive gestational weight gain and 53.3% of women gained 5 kg or more postpartum weight retention. In addition, the proportions of underweight women with inadequate weight gain and overweight women with excessive weight gain were 24.2% and 52.3%, respectively. Logistic regression analysis showed that the adjusted OR of excessive gestational weight gain was 1.74 (95% CI: 1.09e2.79) in overweight women compared with normal weight women. The postpartum weight retention and the proportion of women with postpartum weight retention of 5 kg or more were significantly higher in the excessive gestational weight gain women than in the adequate gestational weight gain women in all three body mass index groups. The adjusted OR of a weight increase of 5 kg or more was at least 1.90 for underweight, normal weight, and overweight women with a gestational weight gain above the recommended amount compared with those with a gestational weight gain within the recommended amount. Conclusions: Gestational weight gain above the recommended amount increases the risk of postpartum weight retention in all body mass index groups. Ó 2014 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.
Keywords: Gestational weight gain Postpartum weight retention Body mass index
1. Introduction Obesity is associated with increased risk of morbidity and mortality related to cardiovascular disease, diabetes, and kidney disease [1]. The prevalence of both overweight and obesity has been steadily increasing in all age groups for several decades in China [2]. Pregnancy is one of the natural and biological causes of weight recycling in the human population [3]. Pregnancy could cause substantial weight gain and alter the future weight gain path
* Corresponding author. School of Public Health, Peking University Health Science Center, 38 Xueyuan Road, Haidian District, Beijing 100191, China. Tel.: þ86 10 82801743; fax: þ86 10 82801519. ** Corresponding author. E-mail address: [email protected] (P. Wang).
[4]. Weight gain from pregnancy may lead to obesity [5]. Among pregnant women, 10%e15% may retain the weight gained during pregnancy on a long-term basis, with a fraction of those becoming obese [5]. Postpartum weight retention (PPWR) is an important nutritional problem for women of childbearing age. According to a review by Gunderson and Abrams, PPWR is most likely due to a combination of factors, such as dietary intake, lack of physical activity, lactation, smoking status, prepregnancy body mass index (BMI), gestational weight gain (GWG), and parity [6]. Among the various factors determining PPWR, GWG is the most relevant, as indicated by an apparent association between GWG and PPWR [7]. Women with GWG above the upper limit as recommended by the Institute of Medicine (IOM) have twice the probability of retaining 9 kg PPWR compared with women with GWG within the IOM
http://dx.doi.org/10.1016/j.clnu.2014.04.010 0261-5614/Ó 2014 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.
Please cite this article in press as: Ma D, et al., Association between gestational weight gain according to prepregnancy body mass index and short postpartum weight retention in postpartum women, Clinical Nutrition (2014), http://dx.doi.org/10.1016/j.clnu.2014.04.010
2
D. Ma et al. / Clinical Nutrition xxx (2014) 1e5
recommendations [8]. In addition, longitudinal studies have shown a relationship between GWG and subsequent maternal obesity, and indicated that GWG along with weight retention at 1 year postpartum is associated with long-term obesity [8,9]. Weight gain and obesity development in childbearing women are of primary concern because numerous adverse health outcomes, such as hypertension, osteoarthritis, gall bladder disease, coronary heart disease, type 2 diabetes, and several cancers, have been associated with weight gain and/or overweight and obesity in women [10]. Thus, assessing the relationship among prepregnancy BMI, GWG, and PPWR and illuminating the predictors of the amount of weight retained by women after pregnancy warrant special attention. However, no study has investigated the relationship among prepregnancy BMI, GWG, and PPWR by Chinese women until now. The present study aims to investigate the association between GWG and PPWR, which is defined as weight retention at 1e2 months, 3e5 months, and 6e11 months after delivery, in relation to different prepregnancy BMI groups (underweight, normal weight, and overweight) in an extensive crosssectional study. 2. Materials and methods 2.1. Sampling This study is part of the Maternal Infant Nutrition and Growth (MING) Study, sponsored by Nestlé Nutrition Institute China and Nestlé Research Center. The MING Study is a cross-sectional survey carried out in 8 Chinese cities, looking at nutrition and dietary status of pregnant mothers, lactating mothers, infants (0e12 months old), and toddlers (13e36 months old). Also, the breast milk of lactating mothers was collected at various lactation periods, with the objective to understand the breast milk composition profile of Chinese lactating mothers. A multistage-stratified random sampling was used in the study. Eight cities were selected, and two maternal and child care service centers from each city (one in suburban area and the other in urban area) were randomly selected. A stratified sample, including 90 infants aged 1 month to 2 months and their mothers, 60 infants aged 3 monthse5 months and their mothers, and 60 infants aged 6 monthse11 months and their mothers, was randomly obtained. The study’s selection criteria included healthy, nonsmoking mothers with primiparous, singleton births and full-term infants. The study was conducted according to the guidelines in the Declaration of Helsinki. All of the procedures involving human subjects were approved by the Medical Ethics Research Board of Peking University (Approval Number: IRB00001052-11042). Written informed consent was obtained from the mother of each infant participating in the study. 2.2. Anthropometric and questionnaire interviews Infants and their mothers were assessed in local maternal and child care service centers. Anthropometric indices (length and weight) were measured by trained research assistants following standardized procedures and using calibrated equipment. Recumbent length was measured and recorded to the nearest 0.1 cm. Weight was obtained and recorded to the nearest 0.1 kg. Each measurement was repeated two times, and the mean value was calculated. Other characteristics were obtained: infant information, such as age, sex, birthday, and delivery mode; social-economic status, such as household composition, family income, maternal age, education, marital status, and employment status of the parents; and feeding information, such as feeding approach, breastfeeding duration, and introduction of foods. In this study, the
educational level was dichotomized into women who had completed high school education and those who did not. The income level was stratified to three levels: 6000 Yuan. Delivery modes included cesarean section and natural delivery. In this study, prepregnancy weight and height, delivery weight and height, and baby birth weight were self-reported. Postpartum weight and height were obtained through face-to-face interviews facilitated by trained research assistants following standardized procedures. The total GWG was calculated by subtracting prepregnancy weight from delivery weight. All women subjects were stratified according to the WHO BMI classification: BMI less than 18.5 kg/m2 (underweight), BMI 18.5 kg/m2 to 24.9 kg/m2 (normal weight), BMI 25.0 kg/m2 to 29.9 kg/m2 (overweight), and BMI 30.0 kg/m2 or greater (obese). The IOM-recommended GWG in 2009 was as follows: between 12.5 kg and 18 kg (28 lbse40 lbs) for underweight women, 11.5 kge16 kg (25 lbse35 lbs) for normal weight women, 7 kge11.5 kg (15 lbse25 lbs) for overweight women; and 5 kge9 kg (11 lbse20 lbs) for obese women [11]. Two outcome measures were defined to investigate PPWR, the first of which was the total postpartum weight change (kg) as a continuous variable. This outcome measure was defined as the difference between postpartum weight (measured during interview) and selfreported prepregnancy weight. The second outcome measure was the substantial PPWR as a dichotomous variable. This outcome measure was defined as weight retention 5 kg based on previous studies wherein 5 kg was designated as the cut-off value for PPWR of less than 1 year [9]. 2.3. Data analysis The differences in the proportion of GWG according to IOM recommendation (inadequate, adequate, or excessive) among different variables, including prepregnancy BMI, maternal age, educational level, income level, delivery mode, and baby birth weight, were analyzed by chi-square test. One-way ANOVA with LSD test was performed to assess the differences in PPWR at 1 monthe2 months, 3 monthse5 months, or 6 monthse11 months according to different maternal characteristics, such as prepregnancy BMI, GWG according to IOM recommendation, maternal age, educational level, income level, delivery mode, and infant feeding method. Logistic regression analysis was used to clarify the predictors for GWG and PPWR. P values were two-tailed, with P < 0.05 being considered statistically significant. Data were presented as mean SE. Statistical analyses were performed using SPSS 20.0 (SPSS Inc., Chicago, IL, USA). 3. Results The subjects in the present research included 1643 women who were stratified by prepregnancy BMI. Of the 1643 subjects, 356 were underweight women, 1155 were normal weight women, and 132 were overweight women. No obese women were investigated in this research. In the total population, the mean GWG was 15.9 kg and the mean PPWR was 5.1 kg. In addition, 43.2% of women gained excessive GWG and 53.3% of women gained 5 kg or more PPWR. Table 1 shows the difference in the proportion of the GWG by IOM recommendations according to different maternal characteristics, including prepregnancy BMI, maternal age, educational level, and income level. The mean GWG decreased with increasing BMI group. Correspondingly, the BMI groups also had significant different patterns of GWG category according to IOM recommendations. Underweight women had the most potential to gain weight within the recommended amount (39.6%), and overweight women had the least potential to gain weight within the
Please cite this article in press as: Ma D, et al., Association between gestational weight gain according to prepregnancy body mass index and short postpartum weight retention in postpartum women, Clinical Nutrition (2014), http://dx.doi.org/10.1016/j.clnu.2014.04.010
D. Ma et al. / Clinical Nutrition xxx (2014) 1e5
3
Table 1 The difference in the proportion of the gestational weight gain (GWG) by Institute of Medicine recommendations according to different maternal characteristics, including prepregnancy body mass index (BMI), maternal age, education level, income level, delivery mode, and baby birth weight. Maternal characteristic
No.
Mean (SE) of GWG
Total Prepregnancy BMI (kg/m2) Underweight Normal Overweight Maternal age, years 25 25e30 >30 Education Less than high school Above high school Income (RMB, Yuan) 6000 Delivery mode Cesarean section Natural delivery Baby birth weight Mean (SE) Low (30 442 4.74 (0.27) Education high school 697 4.71 (0.22) >high school 945 5.4 (0.17) Income (RMB, Yuan) 2000 452 4.81 (0.27) 2000e6000 802 5.43 (0.19) >6000 301 4.68 (0.32) Delivery mode Cesarean 848 5.52 (0.2) Natural 775 4.64 (0.19) Baby feeding method Artificial 381 5.0 (0.31) Breast 644 4.88 (0.21) Mix 616 5.43 (0.22) a
P
No.
3e5 months
Mean (SE)
664 of Medicine 0.001 159 223 282
P
6.18 (0.22)
No.
Mean (SE)
498
5.23 (0.25)
6e11 months P
No.
Mean (SE)
481
a
1.96 (0.42) 5.42 (0.25) 9.15 (0.32)a
0.01
119 172 207
2.93 (0.46) 3.92 (0.34) 7.63 (0.39)a
0.01
98 163 220
P
3.52 (0.23)
0.01
a
1.31 (0.57) 2.86 (0.30) 5.00 (0.34)a
0.01
0.001
149 469 46
7.47 (0.38)a 6.4 (0.24) 0.27 (1.1)a
0.01
96 359 43
5.57 (0.51) 5.46 (0.28) 2.53 (1.09)a
0.01
111 328 42
0.2
159 323 174
6.80 (0.47) 6.08 (0.32) 5.85 (0.40)
0.3
147 225 119
4.73 (0.45) 5.45 (0.34) 5.37 (0.58)
0.4
107 218 149
3.11 (0.56) 4.09 (0.30) 2.95 (0.42)a
0.06
0.01
257 406
5.93 (0.39) 6.32 (0.26)
0.4
220 278
4.74 (0.36) 5.61 (0.34)
0.08
220 261
3.24 (0.38) 3.76 (0.28)
0.5
0.05
171 320 126
6.14 (0.43) 6.35 (0.31) 5.64 (0.56)
0.5
154 245 81
4.91 (0.47) 5.80 (0.36) 4.20 (0.46)a
0.04
127 237 94
2.90 (0.44) 3.79 (0.32) 3.80 (0.55)
0.2
0.002
359 294
6.33 (0.31) 4.94 (0.31)
0.01
264 229
5.97 (0.36) 4.38 (0.33)
0.01
225 252
4.68 (0.35) 3.37 (0.31)
0.01
0.2
176 254 234
6.17 (0.42) 5.72 (0.37) 6.67 (0.35)
0.2
143 185 170
4.3 (0.51) 5.52 (0.37) 5.69 (0.42)
0.08
62 205 212
3.28 (0.79) 3.26 (0.32) 3.87 (0.35)
0.4
3.99 (0.47) 3.82 (0.25) 0.06 (1.1)a
0.01
P < 0.05.
prepregnancy BMI category. Nearly 24.2% of the underweight women in our population gained less weight than the recommended amount. This BMI group would probably benefit the most from weight gain. These women have an increased risk for complications, such as osteoporosis, preterm delivery, and low-birthweight infant if they gained less weight than the recommended amount [13,14]. A large GWG increases the risk of macrosomia and delivery complications, such as cesarean section, instrumental delivery, and shoulder dystocia, even in the absence of macrosomia [15]. Similar to previous results, the present results suggest that excessive GWG during pregnancy significantly increases the proportion of cesarean section and macrosomia. Prepregnancy BMI is negatively associated while GWG is positively associated with PPWR in the present research. Our results are in accordance with previous studies. Baker et al [16]. found that prepregnancy BMI is negatively associated with weight retention at 6 months postpartum. Margerison et al [17]. reported that higher GWG translates to greater risk of PPWR in all BMI groups. Overweight women already have considerable fat reserves
for energy during labor and lactation; therefore, these women may not gain as much weight as women with minimal fat reserves. Despite the fact that the mean PPWR for overweight women is small and even negative in some cases at 1 year postpartum, almost 50% of overweight women with excessive GWG in our study gained 5 kg (11 lbs) at 1 year postpartum in the present research. Breastfeeding in relation to postpartum weight changes has been studied frequently; however, evidence remains inconclusive, ranging from negative to weak positive associations, or no significant association at all [18,19]. In the present study, the infant feeding method was not associated with statistically significant differences in the amount of retained weight. This result may be attributed to the brief time span under study. Lactation seems to have a more significant effect in the long-term follow-up than in the short-term follow-up [20]. Rooney and Schauberger [20] reported that although breastfeeding may not have an effect on short-term weight loss, women who breast-fed their infants for at least 3 months have a significantly lower weight gain at 8-year follow-up.
Table 3 Proportion of women with postpartum weight retention (PPWR) of 5 kg or more in relation to gestational weight gain, prepregnancy body mass index, and delivery mode. Maternal characteristic
PPWR < 5 kg N (%)
PPWR 5 kg N (%)
Gestational weight gain according to Institute of Medicine Inadequate 266 (70.7) 110 (29.3) Adequate 284 (50.9) 274 (49.1) Excessive 211 (29.8) 498 (70.2) 2 Prepregnancy body mass index (kg/m ) Underweight BMI
Contents lists available at ScienceDirect
Clinical Nutrition journal homepage: http://www.elsevier.com/locate/clnu
Association between gestational weight gain according to prepregnancy body mass index and short postpartum weight retention in postpartum women Defu Ma a, Ignatius M.Y. Szeto b, Kai Yu b, Yibing Ning b, Wenjun Li c, Junkuan Wang b, Yingdong Zheng a, Yumei Zhang a, **, Peiyu Wang a, * a b c
School of Public Health, Peking University Health Science Center, Beijing, China Nestlé Research Center, Beijing, China Nestlé Nutrition Institute of China, China
a r t i c l e i n f o
s u m m a r y
Article history: Received 6 February 2014 Accepted 15 April 2014
Background & aims: This study aims to assess the relationship among prepregnancy body mass index, gestational weight gain, and postpartum weight retention, and to clarify the predictors of the amount of weight retained by Chinese women after pregnancy. Methods: The multistage stratified random sampling was used in the cross-sectional study. Results: The subjects included 1643 women. Mean gestational weight gain was 15.9 kg and mean postpartum weight retention was 5.1 kg. 43.2% of women gained excessive gestational weight gain and 53.3% of women gained 5 kg or more postpartum weight retention. In addition, the proportions of underweight women with inadequate weight gain and overweight women with excessive weight gain were 24.2% and 52.3%, respectively. Logistic regression analysis showed that the adjusted OR of excessive gestational weight gain was 1.74 (95% CI: 1.09e2.79) in overweight women compared with normal weight women. The postpartum weight retention and the proportion of women with postpartum weight retention of 5 kg or more were significantly higher in the excessive gestational weight gain women than in the adequate gestational weight gain women in all three body mass index groups. The adjusted OR of a weight increase of 5 kg or more was at least 1.90 for underweight, normal weight, and overweight women with a gestational weight gain above the recommended amount compared with those with a gestational weight gain within the recommended amount. Conclusions: Gestational weight gain above the recommended amount increases the risk of postpartum weight retention in all body mass index groups. Ó 2014 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.
Keywords: Gestational weight gain Postpartum weight retention Body mass index
1. Introduction Obesity is associated with increased risk of morbidity and mortality related to cardiovascular disease, diabetes, and kidney disease [1]. The prevalence of both overweight and obesity has been steadily increasing in all age groups for several decades in China [2]. Pregnancy is one of the natural and biological causes of weight recycling in the human population [3]. Pregnancy could cause substantial weight gain and alter the future weight gain path
* Corresponding author. School of Public Health, Peking University Health Science Center, 38 Xueyuan Road, Haidian District, Beijing 100191, China. Tel.: þ86 10 82801743; fax: þ86 10 82801519. ** Corresponding author. E-mail address: [email protected] (P. Wang).
[4]. Weight gain from pregnancy may lead to obesity [5]. Among pregnant women, 10%e15% may retain the weight gained during pregnancy on a long-term basis, with a fraction of those becoming obese [5]. Postpartum weight retention (PPWR) is an important nutritional problem for women of childbearing age. According to a review by Gunderson and Abrams, PPWR is most likely due to a combination of factors, such as dietary intake, lack of physical activity, lactation, smoking status, prepregnancy body mass index (BMI), gestational weight gain (GWG), and parity [6]. Among the various factors determining PPWR, GWG is the most relevant, as indicated by an apparent association between GWG and PPWR [7]. Women with GWG above the upper limit as recommended by the Institute of Medicine (IOM) have twice the probability of retaining 9 kg PPWR compared with women with GWG within the IOM
http://dx.doi.org/10.1016/j.clnu.2014.04.010 0261-5614/Ó 2014 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.
Please cite this article in press as: Ma D, et al., Association between gestational weight gain according to prepregnancy body mass index and short postpartum weight retention in postpartum women, Clinical Nutrition (2014), http://dx.doi.org/10.1016/j.clnu.2014.04.010
2
D. Ma et al. / Clinical Nutrition xxx (2014) 1e5
recommendations [8]. In addition, longitudinal studies have shown a relationship between GWG and subsequent maternal obesity, and indicated that GWG along with weight retention at 1 year postpartum is associated with long-term obesity [8,9]. Weight gain and obesity development in childbearing women are of primary concern because numerous adverse health outcomes, such as hypertension, osteoarthritis, gall bladder disease, coronary heart disease, type 2 diabetes, and several cancers, have been associated with weight gain and/or overweight and obesity in women [10]. Thus, assessing the relationship among prepregnancy BMI, GWG, and PPWR and illuminating the predictors of the amount of weight retained by women after pregnancy warrant special attention. However, no study has investigated the relationship among prepregnancy BMI, GWG, and PPWR by Chinese women until now. The present study aims to investigate the association between GWG and PPWR, which is defined as weight retention at 1e2 months, 3e5 months, and 6e11 months after delivery, in relation to different prepregnancy BMI groups (underweight, normal weight, and overweight) in an extensive crosssectional study. 2. Materials and methods 2.1. Sampling This study is part of the Maternal Infant Nutrition and Growth (MING) Study, sponsored by Nestlé Nutrition Institute China and Nestlé Research Center. The MING Study is a cross-sectional survey carried out in 8 Chinese cities, looking at nutrition and dietary status of pregnant mothers, lactating mothers, infants (0e12 months old), and toddlers (13e36 months old). Also, the breast milk of lactating mothers was collected at various lactation periods, with the objective to understand the breast milk composition profile of Chinese lactating mothers. A multistage-stratified random sampling was used in the study. Eight cities were selected, and two maternal and child care service centers from each city (one in suburban area and the other in urban area) were randomly selected. A stratified sample, including 90 infants aged 1 month to 2 months and their mothers, 60 infants aged 3 monthse5 months and their mothers, and 60 infants aged 6 monthse11 months and their mothers, was randomly obtained. The study’s selection criteria included healthy, nonsmoking mothers with primiparous, singleton births and full-term infants. The study was conducted according to the guidelines in the Declaration of Helsinki. All of the procedures involving human subjects were approved by the Medical Ethics Research Board of Peking University (Approval Number: IRB00001052-11042). Written informed consent was obtained from the mother of each infant participating in the study. 2.2. Anthropometric and questionnaire interviews Infants and their mothers were assessed in local maternal and child care service centers. Anthropometric indices (length and weight) were measured by trained research assistants following standardized procedures and using calibrated equipment. Recumbent length was measured and recorded to the nearest 0.1 cm. Weight was obtained and recorded to the nearest 0.1 kg. Each measurement was repeated two times, and the mean value was calculated. Other characteristics were obtained: infant information, such as age, sex, birthday, and delivery mode; social-economic status, such as household composition, family income, maternal age, education, marital status, and employment status of the parents; and feeding information, such as feeding approach, breastfeeding duration, and introduction of foods. In this study, the
educational level was dichotomized into women who had completed high school education and those who did not. The income level was stratified to three levels: 6000 Yuan. Delivery modes included cesarean section and natural delivery. In this study, prepregnancy weight and height, delivery weight and height, and baby birth weight were self-reported. Postpartum weight and height were obtained through face-to-face interviews facilitated by trained research assistants following standardized procedures. The total GWG was calculated by subtracting prepregnancy weight from delivery weight. All women subjects were stratified according to the WHO BMI classification: BMI less than 18.5 kg/m2 (underweight), BMI 18.5 kg/m2 to 24.9 kg/m2 (normal weight), BMI 25.0 kg/m2 to 29.9 kg/m2 (overweight), and BMI 30.0 kg/m2 or greater (obese). The IOM-recommended GWG in 2009 was as follows: between 12.5 kg and 18 kg (28 lbse40 lbs) for underweight women, 11.5 kge16 kg (25 lbse35 lbs) for normal weight women, 7 kge11.5 kg (15 lbse25 lbs) for overweight women; and 5 kge9 kg (11 lbse20 lbs) for obese women [11]. Two outcome measures were defined to investigate PPWR, the first of which was the total postpartum weight change (kg) as a continuous variable. This outcome measure was defined as the difference between postpartum weight (measured during interview) and selfreported prepregnancy weight. The second outcome measure was the substantial PPWR as a dichotomous variable. This outcome measure was defined as weight retention 5 kg based on previous studies wherein 5 kg was designated as the cut-off value for PPWR of less than 1 year [9]. 2.3. Data analysis The differences in the proportion of GWG according to IOM recommendation (inadequate, adequate, or excessive) among different variables, including prepregnancy BMI, maternal age, educational level, income level, delivery mode, and baby birth weight, were analyzed by chi-square test. One-way ANOVA with LSD test was performed to assess the differences in PPWR at 1 monthe2 months, 3 monthse5 months, or 6 monthse11 months according to different maternal characteristics, such as prepregnancy BMI, GWG according to IOM recommendation, maternal age, educational level, income level, delivery mode, and infant feeding method. Logistic regression analysis was used to clarify the predictors for GWG and PPWR. P values were two-tailed, with P < 0.05 being considered statistically significant. Data were presented as mean SE. Statistical analyses were performed using SPSS 20.0 (SPSS Inc., Chicago, IL, USA). 3. Results The subjects in the present research included 1643 women who were stratified by prepregnancy BMI. Of the 1643 subjects, 356 were underweight women, 1155 were normal weight women, and 132 were overweight women. No obese women were investigated in this research. In the total population, the mean GWG was 15.9 kg and the mean PPWR was 5.1 kg. In addition, 43.2% of women gained excessive GWG and 53.3% of women gained 5 kg or more PPWR. Table 1 shows the difference in the proportion of the GWG by IOM recommendations according to different maternal characteristics, including prepregnancy BMI, maternal age, educational level, and income level. The mean GWG decreased with increasing BMI group. Correspondingly, the BMI groups also had significant different patterns of GWG category according to IOM recommendations. Underweight women had the most potential to gain weight within the recommended amount (39.6%), and overweight women had the least potential to gain weight within the
Please cite this article in press as: Ma D, et al., Association between gestational weight gain according to prepregnancy body mass index and short postpartum weight retention in postpartum women, Clinical Nutrition (2014), http://dx.doi.org/10.1016/j.clnu.2014.04.010
D. Ma et al. / Clinical Nutrition xxx (2014) 1e5
3
Table 1 The difference in the proportion of the gestational weight gain (GWG) by Institute of Medicine recommendations according to different maternal characteristics, including prepregnancy body mass index (BMI), maternal age, education level, income level, delivery mode, and baby birth weight. Maternal characteristic
No.
Mean (SE) of GWG
Total Prepregnancy BMI (kg/m2) Underweight Normal Overweight Maternal age, years 25 25e30 >30 Education Less than high school Above high school Income (RMB, Yuan) 6000 Delivery mode Cesarean section Natural delivery Baby birth weight Mean (SE) Low (30 442 4.74 (0.27) Education high school 697 4.71 (0.22) >high school 945 5.4 (0.17) Income (RMB, Yuan) 2000 452 4.81 (0.27) 2000e6000 802 5.43 (0.19) >6000 301 4.68 (0.32) Delivery mode Cesarean 848 5.52 (0.2) Natural 775 4.64 (0.19) Baby feeding method Artificial 381 5.0 (0.31) Breast 644 4.88 (0.21) Mix 616 5.43 (0.22) a
P
No.
3e5 months
Mean (SE)
664 of Medicine 0.001 159 223 282
P
6.18 (0.22)
No.
Mean (SE)
498
5.23 (0.25)
6e11 months P
No.
Mean (SE)
481
a
1.96 (0.42) 5.42 (0.25) 9.15 (0.32)a
0.01
119 172 207
2.93 (0.46) 3.92 (0.34) 7.63 (0.39)a
0.01
98 163 220
P
3.52 (0.23)
0.01
a
1.31 (0.57) 2.86 (0.30) 5.00 (0.34)a
0.01
0.001
149 469 46
7.47 (0.38)a 6.4 (0.24) 0.27 (1.1)a
0.01
96 359 43
5.57 (0.51) 5.46 (0.28) 2.53 (1.09)a
0.01
111 328 42
0.2
159 323 174
6.80 (0.47) 6.08 (0.32) 5.85 (0.40)
0.3
147 225 119
4.73 (0.45) 5.45 (0.34) 5.37 (0.58)
0.4
107 218 149
3.11 (0.56) 4.09 (0.30) 2.95 (0.42)a
0.06
0.01
257 406
5.93 (0.39) 6.32 (0.26)
0.4
220 278
4.74 (0.36) 5.61 (0.34)
0.08
220 261
3.24 (0.38) 3.76 (0.28)
0.5
0.05
171 320 126
6.14 (0.43) 6.35 (0.31) 5.64 (0.56)
0.5
154 245 81
4.91 (0.47) 5.80 (0.36) 4.20 (0.46)a
0.04
127 237 94
2.90 (0.44) 3.79 (0.32) 3.80 (0.55)
0.2
0.002
359 294
6.33 (0.31) 4.94 (0.31)
0.01
264 229
5.97 (0.36) 4.38 (0.33)
0.01
225 252
4.68 (0.35) 3.37 (0.31)
0.01
0.2
176 254 234
6.17 (0.42) 5.72 (0.37) 6.67 (0.35)
0.2
143 185 170
4.3 (0.51) 5.52 (0.37) 5.69 (0.42)
0.08
62 205 212
3.28 (0.79) 3.26 (0.32) 3.87 (0.35)
0.4
3.99 (0.47) 3.82 (0.25) 0.06 (1.1)a
0.01
P < 0.05.
prepregnancy BMI category. Nearly 24.2% of the underweight women in our population gained less weight than the recommended amount. This BMI group would probably benefit the most from weight gain. These women have an increased risk for complications, such as osteoporosis, preterm delivery, and low-birthweight infant if they gained less weight than the recommended amount [13,14]. A large GWG increases the risk of macrosomia and delivery complications, such as cesarean section, instrumental delivery, and shoulder dystocia, even in the absence of macrosomia [15]. Similar to previous results, the present results suggest that excessive GWG during pregnancy significantly increases the proportion of cesarean section and macrosomia. Prepregnancy BMI is negatively associated while GWG is positively associated with PPWR in the present research. Our results are in accordance with previous studies. Baker et al [16]. found that prepregnancy BMI is negatively associated with weight retention at 6 months postpartum. Margerison et al [17]. reported that higher GWG translates to greater risk of PPWR in all BMI groups. Overweight women already have considerable fat reserves
for energy during labor and lactation; therefore, these women may not gain as much weight as women with minimal fat reserves. Despite the fact that the mean PPWR for overweight women is small and even negative in some cases at 1 year postpartum, almost 50% of overweight women with excessive GWG in our study gained 5 kg (11 lbs) at 1 year postpartum in the present research. Breastfeeding in relation to postpartum weight changes has been studied frequently; however, evidence remains inconclusive, ranging from negative to weak positive associations, or no significant association at all [18,19]. In the present study, the infant feeding method was not associated with statistically significant differences in the amount of retained weight. This result may be attributed to the brief time span under study. Lactation seems to have a more significant effect in the long-term follow-up than in the short-term follow-up [20]. Rooney and Schauberger [20] reported that although breastfeeding may not have an effect on short-term weight loss, women who breast-fed their infants for at least 3 months have a significantly lower weight gain at 8-year follow-up.
Table 3 Proportion of women with postpartum weight retention (PPWR) of 5 kg or more in relation to gestational weight gain, prepregnancy body mass index, and delivery mode. Maternal characteristic
PPWR < 5 kg N (%)
PPWR 5 kg N (%)
Gestational weight gain according to Institute of Medicine Inadequate 266 (70.7) 110 (29.3) Adequate 284 (50.9) 274 (49.1) Excessive 211 (29.8) 498 (70.2) 2 Prepregnancy body mass index (kg/m ) Underweight BMI
