A Longitudinal Study of Pre-pregnancy and Pregnancy Risk Factors Associated with Antenatal and Postnatal Symptoms of Depression: Evidence from Growing Up in New Zealand.

Objectives Antenatal and postnatal depression can lead to poor outcomes for women and their children. The aim of this study was to explore whether risk factors differ for depression symptoms that are present during pregnancy and/or after childbirth. Methods An ethnically and socioeconomically diverse sample of 5301 women completed interviews during the third trimester of pregnancy and 9 months after childbirth. Depression symptoms were measured using the Edinburgh Postnatal Depression Scale (EPDS). Depression symptoms (defined as EPDS >12) among participants and associations with pre-pregnancy and pregnancy maternal characteristics were explored using logistic regression. Results The rate of antenatal depression symptoms (ADS) only was 8.5, 5% of women had depression symptoms at 9 months postpartum (PDS) only and 3% experienced depression symptoms at both time points. Perceived stress and Pacific or Asian ethnicity were risk factors for ADS and PDS. Anxiety during and before pregnancy was a risk factor for ADS only while having a pre-pregnancy diagnosis of depression was a risk factor for PDS only. Having ADS increased the odds ratio of PDS by 1.5 (95% CI 1.01-2.30). Conclusions The results supported evidence from previous longitudinal studies that depression symptoms appear to be higher during pregnancy than in the first year following childbirth. The study found that PDS may often be a continuation or recurrence of ADS.