The relationship between perinatal psychiatric disorders and the use of effective contraceptive methods among postpartum women served by primary care clinics has not been established.This was a prospective cohort study with 831 pregnant women recruited from 10 primary care clinics of the public sector in São Paulo followed up to 18 months after delivery.Among 701 postpartum women, 644 women (91.8%) had resumed sexual activity. Two hundred fifty-three women (39.2%) were classified as using a less effective contraception method (LECM). The presence of perinatal psychiatric disorder (in pregnancy and/or postpartum) was not associated with LECM. Resumption of sexual life 3 months or beyond after delivery was associated with LECM (odds ratio=1.28, 95% confidence interval: 1.02-1.56).Although the use of an LECM after delivery is common, contraception choice is not associated with perinatal depressive/anxiety symptoms. However, women who delay the resumption of sexual activity after delivery should be counseled on the use of available contraceptive methods.