Background: To evaluate the indications for admission and mortality rates of women of reproductive age admitted to a tertiary Intensive Care Unit (ICU) and to compare the outcomes of obstetric and non-obstetric admissions. Methods: A retrospective cohort study was performed, including all women aged 17–41 years admitted to a level 3 ICU in the Netherlands, between January 1, 2000 and January 1, 2016. Primary outcome was indication for admission and mortality. Mortality, length of stay (LOS), need for mechanical ventilation and APACHE II score were compared between obstetric and non-obstetric admissions. The obstetric group was further analyzed for maternal and perinatal outcomes. Results: 3461 women (median age 32 years) were included, with an overall mortality rate of 13.3%. The obstetric group consisted of 265 women (7.7%). The non-obstetric group (n = 3196) was admitted most often for cardiovascular disease (19.6%), followed by oncologic disease (15%). Mortality was the highest in women with oncologic disease (23.9%). The obstetric group had lower mortality compared to the non-obstetric group (4.9% vs. 14%, p < 0.001), despite higher APACHE II score (14 vs. 11, p < 0.001) and a higher ventilation rate (47.9% vs. 39%, p = 0.004). Major surgical or endovascular interventions, besides caesarean section, were performed in 46% of the obstetric group. Perinatal death occurred in 17.2% and of the surviving infants, 63.2% were born preterm and 45.1% required Neonatal Intensive Care Unit admission. Conclusions: Cardiovascular disease is the most important indication for admission and oncologic disease is associated with highest mortality in women of reproductive age. Obstetric patients constitute a small percentage of all ICU admissions in a tertiary ICU center. They have lower mortality rates than non-obstetric young female patients, despite a more severe initial presentation. Nevertheless lasting maternal morbidity and perinatal mortality and morbidity is frequent.