This cohort study, conducted by the Avon Longitudinal Study of Parents and Children, aimed to follow mothers' mood through pregnancy and after childbirth, comparing reported symptoms of depression at each stage. The study included pregnant women resident in Avon with an expected delivery date between April 1, 1991, and December 31, 1992. The Edinburgh Postnatal Depression Scale was used to measure depressive symptom scores at 18 and 32 weeks of pregnancy and 8 weeks and 8 months postpartum. The proportion of women scoring above a threshold indicating probable depressive disorder was also assessed. Key findings include: - Depression scores were higher at 32 weeks of pregnancy than at 8 weeks postpartum (difference in means 0.88, 95% CI 0.79 to 0.97). - There was no significant difference in the distribution of total scores or individual item scores at the four time points. - 1222 (13.5%) women scored above the threshold for probable depression at 32 weeks of pregnancy, 821 (9.1%) at 8 weeks postpartum, and 147 (1.6%) throughout. - More mothers moved above the threshold for depression between 18 weeks and 32 weeks of pregnancy than between 32 weeks of pregnancy and 8 weeks postpartum. The study concluded that symptoms of depression are not more common or severe after childbirth than during pregnancy. Research and clinical efforts should focus on understanding, recognizing, and treating antenatal depression, as it is more common and can have significant consequences for both the mother and the child.This cohort study, conducted by the Avon Longitudinal Study of Parents and Children, aimed to follow mothers' mood through pregnancy and after childbirth, comparing reported symptoms of depression at each stage. The study included pregnant women resident in Avon with an expected delivery date between April 1, 1991, and December 31, 1992. The Edinburgh Postnatal Depression Scale was used to measure depressive symptom scores at 18 and 32 weeks of pregnancy and 8 weeks and 8 months postpartum. The proportion of women scoring above a threshold indicating probable depressive disorder was also assessed. Key findings include: - Depression scores were higher at 32 weeks of pregnancy than at 8 weeks postpartum (difference in means 0.88, 95% CI 0.79 to 0.97). - There was no significant difference in the distribution of total scores or individual item scores at the four time points. - 1222 (13.5%) women scored above the threshold for probable depression at 32 weeks of pregnancy, 821 (9.1%) at 8 weeks postpartum, and 147 (1.6%) throughout. - More mothers moved above the threshold for depression between 18 weeks and 32 weeks of pregnancy than between 32 weeks of pregnancy and 8 weeks postpartum. The study concluded that symptoms of depression are not more common or severe after childbirth than during pregnancy. Research and clinical efforts should focus on understanding, recognizing, and treating antenatal depression, as it is more common and can have significant consequences for both the mother and the child.