Design: systematic review and meta-analysis of 17 randomised trials with usual-care controls
Population: pregnant and postpartum women in prevention-oriented and symptomatic trials
Primary outcome: depressive and anxiety symptom scores
Effect: antenatal depressive symptoms SMD -0.52 (95% CI -0.75 to -0.30), I squared = 46%

A systematic review screened 10,938 records and pooled 17 randomised trials of standalone physical activity - no counselling, no education bundled in - against usual care, in pregnant and postpartum women. Prevention-oriented trials and trials recruiting symptomatic women were analysed separately.

In prevention-oriented trials, physical activity was associated with lower depressive symptom scores antenatally (SMD -0.52, 95% CI -0.75 to -0.30; I squared = 46%; seven trials) and postpartum (SMD -0.33, 95% CI -0.57 to -0.09; I squared = 86%; seven trials). Antenatal anxiety showed no clear effect (SMD -0.03, 95% CI -0.31 to 0.25; three trials). Among already symptomatic women, postpartum depressive scores were lower with activity (SMD -0.38, 95% CI -0.72 to -0.04; three trials). Certainty was graded low to very low throughout.

This supports what most clinicians already advise, and it prices it honestly: a small-to-moderate improvement in symptom scores, not a treatment for established perinatal depression. Exploratory analyses favoured structured programmes around three sessions of 60 minutes a week. Recommend it as part of antenatal care, keep screening with a validated tool, and do not let an exercise plan delay treatment for a woman who is unwell.

Offer a structured activity plan - roughly three 60-minute sessions weekly - rather than 'stay active'
Keep using a validated depression screen; exercise advice is not a substitute for it
Escalate to psychological or drug treatment on symptom severity, not on adherence to exercise
Check obstetric contraindications before recommending moderate-intensity activity
Be realistic about barriers - time, safe space to walk, family expectations after delivery

Why it matters

It separates what exercise does for symptom scores in well women from what it can be expected to do for a woman who is already depressed.

The statistics, in plain English

A standardised mean difference of -0.52 is a small-to-moderate effect on a symptom questionnaire, not a count of women who avoided depression. I squared of 86% for the postpartum estimate means the trials disagreed more than chance explains, so that pooled number is a rough average of dissimilar programmes. Low and very low certainty grades mean the true effect could be meaningfully different from these figures.