Association between the existence of neonatal congenital anomalies and maternal postpartum depression up to 6 months after delivery: The Japan Environment and Children's Study.

Background: Postpartum depression (PPD) is a significant public health concern; however, its association with congenital anomalies (CAs) remains understudied. This study investigated the relationship between CAs and PPD risk and identified persistent patterns of PPD among mothers of infants with and without CAs.

Methods: We analysed data from 86,464 mother-child pairs in the Japan Environment and Children's Study. PPD was assessed using the Edinburgh Postnatal Depression Scale at 1 and 6 months postpartum. Bayesian multiple log-binomial regression was used to examine associations between CAs and PPD.

Results: The risk ratios (RRs) of PPD were higher in the CAs group than in the Non-CAs group at 1 month (RR = 1.06, 95 % credible interval [CrI] = [1.00, 1.12]) and 6 months (RR = 1.11, 95 % CrI = [1.04, 1.18]) postpartum. Four PPD patterns were identified: persistent, recovered, late-onset and resilient. Mothers of neonates with CAs on both late-onset (median OR = 1.13, 95 % CrI = [1.02, 1.25]) and persistent patterns (median OR = 1.13, 95 % CrI = [1.03, 1.24]) tended to have positive associations with CAs compared with the resilient group.

Limitations: Reliance on self-reported PPD measures may introduce bias and lack of differentiation between types and severities of CAs, while the study's focus on mothers alone without including fathers may not capture the full spectrum of parental mental health impacts.

Conclusion: This study suggests that mothers of neonates with CAs have a significantly increased risk of PPD, which persists up to 6 months after delivery.