Background: Pregnancy at extreme ages is a risk factor for maternal, perinatal and infantile death. Aim: To assess the obstetric risk of women over 40 years old. Material and methods: The risk of maternal, late fetal, neonatal and infantile deaths and the risk of low birth weight was assessed in women over 40 years old and compared to the risk of women aged 20-34 years. Data was obtained from the 1999 Annual Report of the National Statistics Institute and the odds ratios (OR) with a 95% confidence interval were calculated. Results: Women over 40 years had a higher risk of maternal death (OR 7.13, 3.31-14.97), late fetal death (OR 2.19, 1.69-2.85), neonatal death (OR 1.8, 1.4-2.32), infantile death (OR 1.8, 1.49-2.18) and low birth weight (OR 1.72, 1.58-1.88). Conclusions: The higher reproductive risk of women over 40 years is confirmed. Better birth control programs at this age will reduce this risk (Rev Méd Chile 2003; 131: 55-59)