A prospective cohort of 908 consecutively enrolled pregnant women with biparietal diameter (DBP) compatible with gestational age equal to or below 21 weeks were followed up regularly at 2-4 weeks intervals. Normal antenatal care routine was applied. The newborns were followed until 7 days postpartum. The setting was two suburban antenatal clinics in Maputo and the delivery ward at the Maputo Central Hospital. The main outcome variables were low birth weight (LBW), preterm delivery, intrauterine fetal death, perinatal death and small for gestational age (SGA). For each of these variables the odds ratio for maternal risk factors was estimated with 95 per cent confidence interval and multiple logistic regression analysis was used. LBW occurred in 16.2 per cent and low maternal weight, low weight gain during pregnancy and not having a living child were risk factors. Prevalence of preterm birth was 15.4 per cent and low weight gain during pregnancy and malaria in the perinatal period were risk factors. Four per cent of mothers delivered stillborns and syphilis serology (positive VDRL test) was a risk factor. Perinatal death occurred in 4.7 per cent. These deaths were associated with being SGA, LBW or preterm at birth. Of the cohort women, 9.7 per cent delivered SGA newborns. It was concluded that maternal constitutional factors, particularly maternal weight gain, maternal height and maternal weight as well as syphilis and malaria during pregnancy, need to be given attention concerning the adverse outcomes addressed. The establishment of an obstetric cohort, followed prospectively, was possible in a low-income setting with limited numbers lost to follow-up at delivery.