589810 research-article2015
APHXXX10.1177/1010539515589810Asia-Pacific Journal of Public HealthZhang et al
Original Article
Effects of Prepregnancy Body Mass Index and Gestational Weight Gain on Pregnancy Outcomes
Asia-Pacific Journal of Public Health 1–11 © 2015 APJPH Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1010539515589810 aph.sagepub.com
Cui Hong Zhang, BS1, Xiang Yu Liu, BS2, Yi Wei Zhan, BS1, Long Zhang, MHS3, Yan Jie Huang, ScM3, and Hong Zhou, PhD1
Abstract To investigate the single and joint effects of prepregnancy body mass index (BMI) and gestational weight gain (GWG) on pregnancy outcomes, electronic medical records of 14 196 women who delivered singleton live infant at a maternal and child health hospital in Beijing, China, in 2012 were reviewed. Logistic regression was used to assess the associations, adjusting for maternal age, height, education, parity, and offspring sex. Women of high prepregnancy BMI or excessive GWG had higher risks of gestational diabetes mellitus, hypertensive disorders in pregnancy, postpartum hemorrhage, caesarean delivery, macrosomia, and large for gestational age infant, while women of inadequate GWG had higher risks of preterm delivery, low birth weight, and small for gestational age infant. Findings suggest that antenatal care providers should help pregnant women control their GWG to normal. Keywords prepregnancy BMI, gestational weight gain, joint effect, pregnancy outcomes
Introduction Nowadays, millions of fertile women are affected by obesity or excessive gestational weight gain (GWG) around the world. The prevalence of overweight and obesity was 26.2% and 22.8% among American reproductive-aged women, respectively.1 And it was 18.2% and 6.0% for Chinese women before pregnancy, respectively.2 According to GWG recommendations, revised by the Institute of Medicine (IOM) in 2009,3 50.4% women in the United States and 57.1% women in China obtained excessive GWG.2,4 Several previous studies have shown that high prepregnancy body mass index (BMI) or excessive GWG may be associated with increased risks of maternal and neonatal outcomes including gestational diabetes mellitus (GDM),5,6 hypertensive disorders in pregnancy (HDP), caesarean delivery, large for gestational age infant (LGA),7,8 and macrosomia.9,10 Conversely, underweight 1Peking
University, Beijing, China of Texas Health Science Center, Houston, TX, USA 3Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA 2University
Corresponding Author: Hong Zhou, Department of Child, Adolescent and Women’s Health, School of Public Health, Peking University, Xueyuan Road 38, Haidian District, Beijing 100191, China. Email: [email protected]
Downloaded from aph.sagepub.com at UNIVERSITE DE MONTREAL on June 27, 2015
2
Asia-Pacific Journal of Public Health
or inadequate GWG may contribute to the increased risks of low birth weight (LBW) and small for gestational age infant (SGA).6,10 However, some of the findings are not consistent, especially for the effect of GWG on GDM (since women who are diagnosed as GDM would take lifestyle interventions to control weight gain, it is more reasonable to use weight gain before diagnosis instead of total GWG as exposure variable).2,11,12 Together with few published studies that assessed the joint effects of prepregnancy BMI and GWG on adverse pregnancy outcomes,2,13 we aimed to gain more insight into the single effects of prepregnancy BMI or GWG on pregnancy outcomes and to evaluate the joint effects of these 2 factors.
Materials and Methods Data of maternal demographic, antenatal care, and delivery were extracted from a maternal and child health hospital in Beijing, China, where pregnant women were required to establish their medical records within the first 12 weeks of gestation and accept systemic antenatal care until delivery. Pregnancy information included maternal age, height, prepregnancy weight, education, medical history, parity, examinations of each antenatal care, and so on. Delivery information included gestational weeks, which were calculated according to the last menstrual period and confirmed by ultrasound, offspring sex, birthweight, length, complications of mother and baby, and so on. A total of 14 335 women who received systemic antenatal care and delivered a live singleton infant in 2012 were enrolled; 139 were excluded (92 for missing weight before pregnancy, 4 for missing height, 7 for missing weight before delivery, 4 for missing maternal age, 6 for missing maternal education, and 26 for the existence of diabetes mellitus or hypertension before pregnancy), leaving a total of 14 196 women in the analysis. (A total of 13 391 women who have the information of weight at 24-27 weeks of gestation were included in the analysis of GDM; 2321 women who selected caesarean delivery without medical indication, which would influence the results of caesarean delivery and postpartum hemorrhage, were excluded, leaving 11 875 women in the analysis of caesarean delivery and postpartum hemorrhage.) Prepregnancy BMI was calculated by self-reported prepregnancy weight (kg)/height2 (m2). Total GWG was calculated as the difference between the weight before delivery and prepregnancy. Since women who are diagnosed as GDM would take lifestyle interventions to control weight gain, we use the average rate of GWG before 24 to 27 weeks of gestation instead of total GWG as exposure variable. The average rate of GWG before 24 to 27 weeks of gestation was calculated as the difference between the weight of the week and prepregnancy, divided by the corresponding gestational weeks. According to the Chinese maternal prepregnancy BMI status14 and the 2009 IOM GWG recommendations,3 normal GWG was defined as follows: 12.5 to 18.0 kg (prepregnancy BMI
APHXXX10.1177/1010539515589810Asia-Pacific Journal of Public HealthZhang et al
Original Article
Effects of Prepregnancy Body Mass Index and Gestational Weight Gain on Pregnancy Outcomes
Asia-Pacific Journal of Public Health 1–11 © 2015 APJPH Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1010539515589810 aph.sagepub.com
Cui Hong Zhang, BS1, Xiang Yu Liu, BS2, Yi Wei Zhan, BS1, Long Zhang, MHS3, Yan Jie Huang, ScM3, and Hong Zhou, PhD1
Abstract To investigate the single and joint effects of prepregnancy body mass index (BMI) and gestational weight gain (GWG) on pregnancy outcomes, electronic medical records of 14 196 women who delivered singleton live infant at a maternal and child health hospital in Beijing, China, in 2012 were reviewed. Logistic regression was used to assess the associations, adjusting for maternal age, height, education, parity, and offspring sex. Women of high prepregnancy BMI or excessive GWG had higher risks of gestational diabetes mellitus, hypertensive disorders in pregnancy, postpartum hemorrhage, caesarean delivery, macrosomia, and large for gestational age infant, while women of inadequate GWG had higher risks of preterm delivery, low birth weight, and small for gestational age infant. Findings suggest that antenatal care providers should help pregnant women control their GWG to normal. Keywords prepregnancy BMI, gestational weight gain, joint effect, pregnancy outcomes
Introduction Nowadays, millions of fertile women are affected by obesity or excessive gestational weight gain (GWG) around the world. The prevalence of overweight and obesity was 26.2% and 22.8% among American reproductive-aged women, respectively.1 And it was 18.2% and 6.0% for Chinese women before pregnancy, respectively.2 According to GWG recommendations, revised by the Institute of Medicine (IOM) in 2009,3 50.4% women in the United States and 57.1% women in China obtained excessive GWG.2,4 Several previous studies have shown that high prepregnancy body mass index (BMI) or excessive GWG may be associated with increased risks of maternal and neonatal outcomes including gestational diabetes mellitus (GDM),5,6 hypertensive disorders in pregnancy (HDP), caesarean delivery, large for gestational age infant (LGA),7,8 and macrosomia.9,10 Conversely, underweight 1Peking
University, Beijing, China of Texas Health Science Center, Houston, TX, USA 3Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA 2University
Corresponding Author: Hong Zhou, Department of Child, Adolescent and Women’s Health, School of Public Health, Peking University, Xueyuan Road 38, Haidian District, Beijing 100191, China. Email: [email protected]
Downloaded from aph.sagepub.com at UNIVERSITE DE MONTREAL on June 27, 2015
2
Asia-Pacific Journal of Public Health
or inadequate GWG may contribute to the increased risks of low birth weight (LBW) and small for gestational age infant (SGA).6,10 However, some of the findings are not consistent, especially for the effect of GWG on GDM (since women who are diagnosed as GDM would take lifestyle interventions to control weight gain, it is more reasonable to use weight gain before diagnosis instead of total GWG as exposure variable).2,11,12 Together with few published studies that assessed the joint effects of prepregnancy BMI and GWG on adverse pregnancy outcomes,2,13 we aimed to gain more insight into the single effects of prepregnancy BMI or GWG on pregnancy outcomes and to evaluate the joint effects of these 2 factors.
Materials and Methods Data of maternal demographic, antenatal care, and delivery were extracted from a maternal and child health hospital in Beijing, China, where pregnant women were required to establish their medical records within the first 12 weeks of gestation and accept systemic antenatal care until delivery. Pregnancy information included maternal age, height, prepregnancy weight, education, medical history, parity, examinations of each antenatal care, and so on. Delivery information included gestational weeks, which were calculated according to the last menstrual period and confirmed by ultrasound, offspring sex, birthweight, length, complications of mother and baby, and so on. A total of 14 335 women who received systemic antenatal care and delivered a live singleton infant in 2012 were enrolled; 139 were excluded (92 for missing weight before pregnancy, 4 for missing height, 7 for missing weight before delivery, 4 for missing maternal age, 6 for missing maternal education, and 26 for the existence of diabetes mellitus or hypertension before pregnancy), leaving a total of 14 196 women in the analysis. (A total of 13 391 women who have the information of weight at 24-27 weeks of gestation were included in the analysis of GDM; 2321 women who selected caesarean delivery without medical indication, which would influence the results of caesarean delivery and postpartum hemorrhage, were excluded, leaving 11 875 women in the analysis of caesarean delivery and postpartum hemorrhage.) Prepregnancy BMI was calculated by self-reported prepregnancy weight (kg)/height2 (m2). Total GWG was calculated as the difference between the weight before delivery and prepregnancy. Since women who are diagnosed as GDM would take lifestyle interventions to control weight gain, we use the average rate of GWG before 24 to 27 weeks of gestation instead of total GWG as exposure variable. The average rate of GWG before 24 to 27 weeks of gestation was calculated as the difference between the weight of the week and prepregnancy, divided by the corresponding gestational weeks. According to the Chinese maternal prepregnancy BMI status14 and the 2009 IOM GWG recommendations,3 normal GWG was defined as follows: 12.5 to 18.0 kg (prepregnancy BMI
