Pet ownership during pregnancy and mothers' mental health conditions up to 1 year postpartum: A nationwide birth cohort—the Japan Environment and Children's Study

Background: Previous studies have investigated the relationship between pet ownership and mental health in various populations, but few have targeted women around childbirth when they have heightened vulnerability to mental disorders. This study therefore examined this association in women around childbirth. Methods: Data were obtained from 80,814 mothers in an ongoing nationwide birth cohort study in Japan. Pet ownership status—none, dog(s) only, cat(s) only, or both—was determined during the second/third trimester of pregnancy. Mental health was assessed using the Edinburgh Postnatal Depression Scale (EPDS) and the Kessler Psychological Distress Scale (K6), with each score measured at two different time points around childbirth. Generalized linear models were used to derive adjusted odds ratios (aORs) and 95% confidence intervals (95% CIs) for pet ownership, with no pet ownership as the reference. Results: Dog ownership was associated with reduced risk of depressive symptoms at 1 month (aOR: 0.97, 95%CI: 0.95–0.98) and 6 months postpartum (aOR: 0.98, 95%CI: 0.96–0.99) and with psychological distress at 12 months postpartum (aOR: 0.96, 95%CI: 0.92–0.999). In contrast, cat ownership was associated with increased risk of depressive symptoms at 6 months postpartum (aOR: 1.04, 95% CI: 1.02–1.06) and psychological distress in the second/third trimester (aOR: 1.07, 95% CI: 1.02–1.12). Ownership of both cats and dogs was associated with increased risk of psychological distress in the second/third trimester (aOR: 1.12, 95% CI: 1.03–1.21) but was largely similar to that of the reference group. Conclusions: Dog ownership was a protective factor for maternal mental health problems, whereas cat ownership was a risk factor. These findings suggest that the type of pet owned, cat or dog, plays a differential role in maintaining mothers’ mental health in the perinatal and postpartum periods.