PurposeAs part of a larger nationwide enquiry into severe maternal morbidity, our aim was to assess the incidence and possible risk factors of obstetric intensive care unit (ICU) admission in the Netherlands.MethodsIn a 2-year nationwide prospective population-based cohort study, all ICU admissions during pregnancy, delivery and puerperium (up to 42 days postpartum) were prospectively collected. Incidence, case fatality rate and possible risk factors were assessed, with special attention to the ethnic background of women.ResultsAll 98 Dutch maternity units participated in the study. There were 847 obstetric ICU admissions in 358,874 deliveries, the incidence being 2.4 per 1,000 deliveries. Twenty-nine maternal deaths occurred, resulting in a case fatality rate of 1 in 29 (3.5%). Incidence of ICU admission varied largely across the country. Thirty-three percent of all cases of severe maternal morbidity were admitted to an ICU. Most frequent reasons for ICU admission were major obstetric haemorrhage (48.6%), hypertensive disorders of pregnancy (29.3%) and sepsis (8.1%). Assisted ventilation was needed in 34.8%, inotropic support in 8.8%. In univariable analysis, non-Western immigrant women had a 1.4-fold (95% CI 1.2–1.7) increased risk of ICU admission as compared to Western women. Initial antenatal care by an obstetrician was associated with a higher risk and home delivery with a lower risk of ICU admission.ConclusionsPopulation-based incidence of obstetric ICU admission in the Netherlands was 2.4 per 1,000 deliveries. Obstetric ICU admission accounts for only one-third of all cases of severe maternal morbidity in the Netherlands.