Objective To examine the association between biochemical vitamin A deficiency in pregnancy and maternal and fetal health. Design A cross sectional clinical study.Setting Antenatal clinic of nutrition unit of Niloufer Hospital catering for a low socio-economic population, and a private nursing home (Swapna nursing home) catering for a high socio-economic population. Population 736 pregnant women in their third trimester of pregnancy belonging to low (n ¼ 522) and high socio-economic groups (n ¼ 214). Methods All the women were subjected to a detailed clinical, anthropometric and obstetric examination. Night blindness was assessed by administering the standard WHO questionnaire. Birthweight and gestational age of the infants, maternal anaemia and development of pregnancy-induced hypertension in the mother were recorded. Haemoglobin and serum retinol were estimated at the time of recruitment to the study. Main outcome measures Serum retinol levels, anaemia, pregnancy-induced hypertension, birthweight and gestational age of the infant. Results Night blindness was observed in 2.9% of the women and subclincal vitamin A deficiency (serum retinol <20 Ag/dL with no clinical signs) in 27% of the women. Moderate to severe anaemia was observed in 41.2% of the women, and 15.8% of the women developed pregnancy-induced hypertension. Sixty-one (9.4%) women delivered preterm. Univariate analysis identified a significant association between serum retinol <20 Ag/dL and preterm delivery (OR ¼ 1.74, 95% CI 1.03 -2.96), maternal anaemia (OR ¼ 1.82, 95% CI 1.28-2.60) and pregnancy-induced hypertension (OR ¼ 1.56, 95% CI 1.02-2.83). After adjusting for the confounding variables (body mass index, parity, age and socio-economic status) in a multivariate analysis, the significant associations between serum retinol <20 Ag/dL and preterm delivery ( P ¼ 0.02) and anaemia ( P ¼ 0.003) persisted, while that for pregnancy-induced hypertension disappeared ( P ¼ 0.71). Conclusion The study suggests that subclinical vitamin A deficiency is a problem during the third trimester of pregnancy. Serum concentration of retinol <20 Ag/dL appears to indicate a deficient status, and is associated with an increased risk of preterm delivery and maternal anaemia.