The authors conducted a retrospective cohort study of pregnant women to estimate the prevalence and associated risk of adverse pregnancy outcomes among pregnant women with microhaematuria. Between 1 January 1993 and 15 March 1993 at University of Washington Medical Center, 328 consecutive births were identified, and demographic data, medical history, laboratory data and pregnancy outcomes were abstracted from hospital charts. The presence or absence of haematuria was determined in 276/328 cases. Sixteen per cent (44/276) of the women were found to have haematuria. Those with haematuria were at increased risk of developing pre-eclampsia (odds ratio [OR] = 9.5, 95% confidence interval [CI] 3.1, 28.2) and premature labour (OR = 3.8, 95% CI 1.5, 9.7). These associations persisted after controlling for age, race, and urinary tract infection (UTI) (pre-eclampsia OR = 9.1, 95% CI 2.5, 33.7; premature labour OR = 4.2, 95% CI 1.2, 15.3). Infants of women with haematuria were at a non-significantly increased risk of low Apgar scores (OR = 2.8, 95% CI 0.7, 11.9) and low birthweight (OR = 1.9, 95% CI 0.7, 4.7). In this observational study, microscopic haematuria was prevalent among pregnant women and was independently associated with an increased risk of adverse maternal complications.