Depression may be associated with a lower likelihood of having children, but the findings are inconsistent. Previous population-based studies on this topic are limited.

We examined associations between depression and the likelihood of having children, the number of children, and the parental age at first birth. We also evaluated whether these associations differ for people with low, middle, and high educational levels.

We conducted a nationwide register cohort study including all individuals born in Finland from 1960 to 1980 (n=1,408,951). Depression diagnoses were identified from the Care Register for Health Care (containing records of inpatient hospital episodes for the period 1969 to 2017 and of specialist outpatient visits for the period 1996 to 2017). The main outcomes—having biological children, the number of biological children, and the parental age at first birth—were identified from the Population Register of Statistics Finland and were defined either in the last year of the follow-up in 2017 or the last year alive or living in Finland. The association between depression and the likelihood of having children was examined using a logistic regression analysis; the association between depression and the number of children was evaluated using Poisson regression analyses, and the association between depression and the age at first birth was evaluated using a linear regression analysis. All analyses were conducted separately for men and women.

For both men and women, secondary care–treated depression was associated with a lower likelihood of having children (odds ratio, 0.66; 95% confidence interval, 0.64–0.67 for men; odds ratio, 0.84; 95% confidence interval, 0.82–0.85 for women) and with having fewer children (incidence rate ratio, 0.86; 95% confidence interval, 0.86–0.87 for men; incidence rate ratio, 0.96; 95% confidence interval, 0.96–0.96 for women). Depression was associated with a slightly lower parental age at first birth (33.1 vs 34.0; P<.001 for men; 31.3 vs 32.1; P<.001 for women). Dose-response associations between the severity of depression and a decreased likelihood of having children, as well as having fewer children, were observed. Earlier onset of depression was related to a lower likelihood of having children and to having fewer children. Among men and women in middle- and high-level educational groups, depression was associated with a lower likelihood of having children and with having fewer children. Among men with a low level of education, no associations were observed. Among women with a low level of education, depression was associated with a higher likelihood of having children and with having more children.

Both men and women with secondary care–treated depression have a lower likelihood of having children and have fewer children. Our findings suggest that depression may be one of the factors that contribute to the likelihood of having children, which should be addressed by policy makers.