To investigate the time-specific effect of maternal exposure to prenatal stressful life events (SLEs) on gestational weight gain (GWG) and to determine whether pre-pregnancy body mass index (BMI) modifies the effect.
Between March and November 2008, data were collected from 1800 pregnant women who received prenatal check-ups in Hefei, China, after 32 completed weeks of gestation. Participants completed a structured interview on demographic characteristics and a checklist of SLEs during different stages of pregnancy. GWG during pregnancy was determined by self-reported pre-pregnancy weight and measured weight at delivery.
There was a significant dose�response relationship between prenatal SLEs in the first, but not the second or third, trimester and GWG. For each 1-unit increase in SLEs during the first trimester, there was a reduction in GWG of approximately 0.497kg (95% confidence interval, 0.176�0.817kg). After stratification by pre-pregnancy BMI, a significant negative association between SLEs in the first trimester and GWG was observed among women with pre-pregnancy normal (?=?0.796; 95% CI, ?1.291 to ?0.301) and low (?=?1.066; 95% CI, ?2.180 to ?0.048) weight.
The effect of prenatal SLEs on GWG depends on the timing of maternal exposure to stress and varies according to pre-pregnancy BMI.