Exercise eased depression in pregnancy, but starting after birth did little

Depression around pregnancy and birth affects mothers at one of the most demanding points in their lives, and its effects can reach the child too. Medication is a complicated choice during pregnancy and breastfeeding, which makes safe, low-cost alternatives genuinely valuable. Exercise is the obvious candidate: it is cheap, widely accessible and already recommended in pregnancy for other reasons. What has been unclear is whether it measurably prevents or reduces depressive symptoms in this specific window, and whether timing, during pregnancy versus after birth, changes the answer.

The researchers systematically searched MEDLINE/PubMed, Web of Science, Scopus and the Cochrane Library for randomised controlled trials published between 2000 and 2024. To qualify, trials had to test an exercise intervention in the perinatal period and report depressive symptoms on the Edinburgh Postnatal Depression Scale, the standard screening questionnaire for this population. Nine trials met the criteria. The team assessed study quality and risk of bias, then pooled the results using a random-effects model, with subgroup analyses separating interventions delivered during pregnancy from those delivered postpartum.

Overall, exercise significantly reduced depressive symptoms, with a pooled standardised effect of -0.47, a moderate benefit. The headline, though, is in the timing. When exercise took place during pregnancy, the effect was stronger, at -0.77. When it took place in the postpartum period, the effect essentially vanished, at -0.05, a result indistinguishable from no benefit. The trials also varied widely in their results, which the authors flag as a reason for caution, alongside the small number of studies available to pool.

This strengthens the case for exercise as a public health tool for maternal mental health, but it complicates the simple message that movement always helps, since the postpartum trials showed almost nothing. Whether that reflects genuine biology, the practical difficulty of exercising with a newborn, or differences in the programmes tested cannot be answered from these data. The authors call for longer follow-up of at least 6 months to see whether benefits last, and for future trials to standardise protocols around at least 150 minutes a week of moderate activity so results can be compared properly.

For anyone pregnant or planning to be, this is a reason to view staying active, where it is medically cleared, as protective for mood and not only for physical health. The timing finding is the practical insight: the window where exercise appeared to matter most was during pregnancy itself, not after the birth. That said, nine trials that disagreed with each other is a thin base, so treat this as a promising signal rather than a settled fact. Anyone experiencing low mood around pregnancy has reasons well beyond this study to raise it with their midwife or doctor.