Does supervised aerobic exercise during pregnancy reduce depressive symptoms in nulliparous women?Randomised trial with concealed allocation, blinded assessors, and intention-to-treat analysis.80 nulliparous, pregnant women attending for prenatal care at one of three tertiary hospitals in Cali, Colombia.The experimental group completed a 3-month supervised exercise program, commencing at 16 to 20 weeks of gestation. Each session included walking (10 min), aerobic exercise (30 min), stretching (10 min), and relaxation (10 min). The control group continued usual activities and performed no specific exercise.The primary outcome was symptoms of depression assessed by the Center for Epidemiological Studies Depression Scale (CES-D) at baseline and immediately after the 3-month intervention.74 women completed the study. After the 3-month intervention, the experimental group reduced their depressive symptoms on the CES-D questionnaire by 4 points (95% CI 1 to 7) more than the control group.A supervised 3-month program of primarily aerobic exercise during pregnancy reduces depressive symptoms.NCT00872365.