This population-based cohort study was conducted to compare pregnancy complications and outcome among nulliparous, low (1-5) and high (> or = 6) parity women. Women who registered for antenatal care and gave birth in Guru District, Zimbabwe, between January 1995 and June 1998 were classified into groups by parity. The women were compared for baseline characteristics, utilisation of health facilities and occurrence of pregnancy complications such as hypertensive disorders of pregnancy, haemorrhage, pre-term delivery, operative delivery, low birth weight and perinatal death. In estimating risk, primiparous (parity = 1) women were used as referents. Pregnancy records for 10,569 women were analysed. Mean ages of nulliparous and high parity (> or = 6) women were 20.1 and 37.7 years respectively (p < 0.001). Prevalence of anaemia at booking (haemoglobin < or =10.5 g/dl) was reduced in nulliparous compared to multiparous women (11.7% vs 16.8%; p > or = 0.001). Nulliparous women were likely to book early (< or = 20 weeks) for antenatal care, have a higher number of visits (> or = 6) and fewer home births. Nulliparous women had higher risk for low birth weight (RR 1.70; 95% CI 1.36 - 2.13). Compared to low parity women, nulliparous and high parity women had an elevated risk of hypertensive complications RR 1.62 (95% CI 1.37-1.92) and RR 1.64 (95% CI 1.29 - 2.07) respectively. The risk of developing any pregnancy complications was highest in nulliparous women (RR 1.48; 95% 1.31- 1.67). In conclusion, nulliparous women had an increased risk of pregnancy complications. High parity women with no previous complicated pregnancy were at low risk of complications.