Depression and antidepressant treatment in growing up in New Zealand: impact on preterm birth and low birth weight

To investigate the independent effects of antenatal depression and antidepressant use on birth weight and gestational age in a large, ethnically diverse New Zealand cohort. Data were obtained from 6,759 pregnancies in the Growing Up in New Zealand longitudinal study, of which 5,200 (76.9%) involved neither antidepressant exposure nor unmedicated depression, 197 (2.9%) involved antidepressant exposure, and 715 (10.6%) involved unmedicated depression. Antenatal depression was assessed using the Edinburgh Postnatal Depression Scale (EPDS), and prenatal antidepressant use was self-reported. Birth outcomes were obtained through linked perinatal health records. Multiple regression analyses examined continuous and categorical outcome definitions, adjusting for sociodemographic and antenatal health variables. The prevalence of antidepressant use and unmedicated antenatal depression (EDPS ≥ 13) was 2.9% and 10.6%, respectively. Antidepressant use predicted a 0.40-week reduction in gestational age (95% CI: -0.55 to -0.26), and each one-point increase in EPDS score predicted a 0.02-week reduction (95% CI: -0.03 to -0.01). Higher EPDS scores were also associated with increased odds of preterm birth (OR = 1.04, 95% CI: 1.02 to 1.07) and low birth weight (OR = 1.03, 95% CI: 1.00 to 1.06). Antidepressant use and antenatal depression were each associated with slightly earlier births, but only depressive symptoms were associated with increased risk of preterm birth and low birth weight. Effect sizes were small. Antidepressants remain an important, and often most accessible treatment option, for maternal depression. Greater investment in screening and culturally responsive, non-pharmacological options is also needed to support diverse preferences and wellbeing.