Maternal prenatal stress during the first trimester and infant birthweight in Soweto, South Africa

Background: Approximately 14.2% of newborns are estimated to be born low birth weight (LBW) in South Africa. Past work has implicated maternal prenatal stress as a potent predictor of poor birth outcomes, including preterm birth, intrauterine growth restriction, and LBW. However, less is presently known about the impacts of prenatal stress during early gestation in low- and middle-income contexts, where public health burdens due to LBW are much higher. Objective: We assess the effects of psychosocial stress during the first trimester on birthweight in a large sample of women (n = 657) in Soweto, South Africa, a peri-urban township located in the Greater Johannesburg area. Methods: Data come from the Soweto First 1000 Days Cohort, a study of maternal and fetal predictors of infant birth outcomes. Multiple regression models were used to examine the impact of prenatal stress on infant birthweight. Results: The prevalence of LBW was 16.6%. Adjusting for maternal age, gestational age, fetal gender, body mass index, and parity, maternal prenatal stress during the first trimester was a borderline predictor of lower birthweight in this sample ({beta} = 12.7, p = 0.071, 95% CI [-26.4, 1.10]). Women who reported greater levels of stress appeared to have non-significantly longer gestations, and the negative impact of maternal stress on birthweight only appeared after adjusting for this pattern. Conclusions: These results suggest that fetal growth restriction associated with first trimester maternal stress may contribute to lower birthweights in this sample. Our findings report modest relationships between maternal stress specific to early gestation as likely important to birth outcomes in this urban South African sample.