Objectives This study explored whether listening to music during pregnancy is longitudinally associated with lower symptoms of postnatal depression and higher well-being in mothers post birth.

Design Prospective cohort study.

Participants We analysed data from 395 new mothers aged over 18 who provided data in the third trimester of pregnancy and 3 and 6 months later (0–3 and 4–6 months post birth).

Primary and secondary outcome measures Postnatal depression was measured using the Edinburgh Postnatal Depression Scale, and well-being was measured using the Short Warwick-Edinburgh Mental Well-being Scale. Our exposure was listening to music and was categorised as ‘rarely; a couple of times a week; every day <1 hour; every day 1–2 hours; every day 3–5 hours; every day 5+hrs’. Multivariable linear regression analyses were carried out to explore the effects of listening to music during pregnancy on depression and well-being post birth, adjusted for baseline mental health and potential confounding variables.

Results Listening during pregnancy is associated with higher levels of well-being (β=0.40, SE=0.15, 95% CI 0.10 to 0.70) and reduced symptoms of postnatal depression (β=−0.39, SE=0.19, 95% CI −0.76 to −0.03) in the first 3 months post birth. However, effects disappear by 4–6 months post birth. These results appear to be particularly found among women with lower levels of well-being and high levels of depression at baseline.

Conclusions Listening to music could be recommended as a way of supporting mental health and well-being in pregnant women, in particular those who demonstrate low well-being or symptoms of postnatal depression.