The course of pregnancy and labour, and perinatal outcome of 182 pregnancies complicated by bronchial asthma, over a 10-year period were studied. Antiasthmatic medications included oral and/or parenteral beta 2-agonists, theophylline, aminophylline, corticosteroids, and inhaled salbutamol and beclomethasone. A control group of 364 nonasthmatic gravidas was matched for age and parity. In asthmatic gravidas, antenatal complications mean duration of pregnancy (38.5 weeks), mode of delivery, incidence of prematurity (13.2%) and low birth weight (LBW, 19.6%) and perinatal mortality (0.5%) were not significantly different compared to the controls (p > 0.05). However, uncontrolled severe asthma in 15 gravidas who required hospitalization, was associated with significant decrease in mean birth weight (2469 +/- 571 g vs 2842 +/- 494 g; p < 0.05) and a high incidence of LBW neonates (53.3% vs 20.5%; p < 0.01) at mean gestation of 38 weeks. Bronchial asthma during pregnancy, when optimally controlled does not affect the course or pregnancy and labour, and perinatal outcome. However, uncontrolled severe asthma leads to fetal growth retardation.