Association Between the Severity of Nausea and Vomiting of Pregnancy and Postpartum Depression: A Retrospective Cohort Study

Aim Nausea and vomiting of pregnancy (NVP) has been suggested as a potential risk factor for postpartum depression. However, existing evidence remains inconclusive because of variations in NVP definitions, limited sample sizes, and limited consideration of parity, despite potential differences in the caregiving burden between these two groups. We examined the association between postpartum depressive symptoms and the severity of NVP, assessed using multiple clinical criteria, stratified by parity. Methods A retrospective cohort study was conducted of 2124 women who received perinatal care from early pregnancy to delivery at a tertiary hospital in Japan between 2018 and 2024. Postpartum depressive symptoms were defined as an Edinburgh Postnatal Depression Scale score ≥ 9 at 1 month postpartum. NVP was clinically diagnosed and classified based on clinical interventions: no treatment, oral antiemetic use, intravenous therapy, and hospitalization. A multivariable logistic regression model was used to estimate adjusted odds ratios (aOR) stratified by parity. Results A total of 128 participants (6.0%) met the criteria for postpartum depressive symptoms. There was a significant interaction between NVP severity and parity ( P for interaction = 0.007). Among primiparous women, NVP was not associated with the risk of postpartum depressive symptoms at any severity level. By contrast, among multiparous women, the risk increased progressively with the severity of NVP ( P for trend = 0.009), with those requiring hospitalization exhibiting a significantly elevated risk (aOR 5.47, 95% confidence interval: 2.14–12.89). Conclusions Multiparous women who experienced severe NVP requiring hospitalization had an increased risk of postpartum depressive symptoms.