Gestational weight gain rate in third trimester relates to maternal and neonatal outcomes in pregnancies with normal glucose tolerance

Abstract

Objective To investigate the association between third-trimester gestational weight gain rate (GWGR) and both maternal and neonatal health outcomes in a normal glucose tolerance obstetric population. Methods This was a retrospective cohort study of full-term singleton live births (n=1 967) in women with a normal oral glucose tolerance test (OGTT) tested at 24-28 gestational weeks, who gave birth at Beijing Obstetrics and Gynecology Hospital, Capital Medical University, between January and December in 2013. The subjects were divided into three groups based on third-trimester GWGR category of the 2009 Institute of Medicine (IOM) guidelines. Each group was divided into three subgroups by pre-pregnancy body mass index (BMI): low (<18.5), normal (≥18.5-<25.0), and high (≥25.0). One-way analysis of variance, Chi-square or Fisher's exact test, Logistic regression and corrected analysis were performed for statistical analysis. Results (1) Of the 1 967 women analyzed, third-trimester weight gain distribution was normal in 575(29.2%), excessive in 982(49.9%), and insufficient in 410(20.8%). No significant differences were found in terms of age, parity, education level, family history of diabetes or hypertension among the GWGR groups (all P>0.05). (2) The mean third-trimester weight gain in the 1 967 normal OGTT women was (0.56±0.23) kg/week and the mean neonatal birth weight was (3 442±396) g. The above two parameters were linearly correlated (Y=103.839X+3383.752, r=0.621, P 0.05). (3) Compared to the normal GWGR group, the excessive GWGR group had an increased incidence of cesarean section [30.2% (297/982) vs 22.2% (128/575)] and hypertensive disorders of pregnancy [4.0% (39/982) vs 1.9% (11/575)] (all P 0.05). (4) In the normal and insufficient GWGR groups, no differences in neonatal birth weight or risk of small-for-gestational age (SGA) or large-for-gestational age (LGA) were seen in any of the BMI subgroups (all P>0.05). In the excessive GWGR group, the high pre-pregnant BMI subgroup showed higher neonatal birth weight than the normal pre-pregnant BMI subgroup [(3 552.3±445.0) vs (3 481.8±416.1) g, P<0.01], and the low pre-pregnant BMI subgroup showed lower neonatal birth weight (3 352.7±371.2) g than the normal pre-pregnant BMI subgroup (P<0.01). Moreover, the high pre-pregnant BMI subgroup in the excessive GWGR group had an increased risk of fetal macrosomia (OR=1.60, 95%CI: 1.11-2.81). Conversely, the low pre-pregnant BMI subgroup in the excessive GWGR group had a decreased risk of fetal macrosomia (OR=0.52, 95%CI: 0.29-0.97) (all P<0.05). The high BMI subgroup had a greater risk of hypertensive disorders of pregnancy than the normal BMI subgroup in all GWGR groups (all P<0.05). The incidence of surgical delivery or NICU admission was not significantly different among the three GWGR subgroups. Conclusions Excessive weight gain in third-trimester is common in normal OGTT women. Excessive gestational weight gain is associated with adverse maternal and neonatal outcomes. Thus, gestational weight gain in the third-trimester should be adequately monitored and a balance in weight gain within the range recommended by the 2009 IOM guidelines should be established in normal OGTT pregnant women. Key words: Pregnancy; Weight gain; Pregnancy trimester, third; Body mass index; Birth weight; Infant, newborn; Pregnancy outcome