Abstract
BackgroundDespite the well-studied effects of gestational weight gain (GWG) on offspring health, little is known about the association of trimester-specific GWG with offspring birth weight among underweight pregnant women. This study aimed to explore the association of trimester-specific GWG rate with small for gestational age (SGA) in underweight women.MethodsThe GWG rate of underweight pregnant women (pre-pregnancy body mass index [BMI] lower than 18.5 kg/m2) of the Born in Guangzhou Cohort Study was calculated as the weight gain during a specific trimester divided by the corresponding duration of week. Total GWG was calculated as the weight difference between pre-pregnancy and delivery, and was categorized into inadequate, adequate, and excessive weight gain based on the 2009 Institute of Medicine (IOM) weight gain recommendation. The INTERGROWTH-21st standards were used to define SGA. Logistic regression models were used to examine the associations of total GWG and trimester-specific GWG rates with SGA. Associations between trimester-specific GWG rates and SGA were also analyzed separately based on different total GWG categories (i.e. inadequate and adequate/excessive GWG).ResultsOf the 3839 participants, SGA births occurred in 397 (10.3%), and mean GWG was 14.9 kg (SD 3.9). A lower risk of SGA was observed among women with higher GWG rate (per 0.5 kg/week increase) during the first (adjusted OR [aOR] 0.74, 95%CI 0.57, 0.96) and second (adjusted OR [aOR] 0.40, 95%CI 0.30, 0.55) but not third trimester. Similar association between higher GWG rate during the second trimester and a decreased risk of SGA were observed among women with inadequate (< 12.5 kg) and adequate/excessive (≥12.5 kg) total GWG, respectively. Compared to women with adequate GWG rate, women with inadequate GWG rate during the second trimester had a significantly increased risk of SGA (aOR 1.58, 95% CI 1.14, 2.20).ConclusionsSecond-trimester GWG might be the key driver for the association between inadequate GWG and increased risk of SGA births in underweight women.
Highlights
Small for gestational age (SGA) is related to increased risks of neonatal and post-neonatal mortality [1], and associated with neurodevelopmental problems and cardiometabolic diseases in later life [2]
Second-trimester gestational weight gain (GWG) might be the key driver for the association between inadequate GWG and increased risk of small for gestational age (SGA) births in underweight women
A recent meta-analysis of 23 studies concluded that total GWG below the recommendations increased the risk of SGA, and that the association was most pronounced in pre-pregnancy underweight women [4]
Summary
Small for gestational age (SGA) is related to increased risks of neonatal and post-neonatal mortality [1], and associated with neurodevelopmental problems and cardiometabolic diseases in later life [2]. The optimal GWG recommendations are based on pre-pregnancy BMI categories: 12.5–18 kg for underweight women (BMI < 18.5 kg/m2); 11.5–16 kg for normal-weight women (BMI 18.5–24.9 kg/m2); 7–11.5 kg for overweight women (BMI 25–29.9 kg/m2); and 5–9 kg for women with obesity (BMI ≥30 kg/m2) [6]. Adherence to these GWG recommendations is low. Despite the well-studied effects of gestational weight gain (GWG) on offspring health, little is known about the association of trimester-specific GWG with offspring birth weight among underweight pregnant women. This study aimed to explore the association of trimester-specific GWG rate with small for gestational age (SGA) in underweight women
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