Introduction: The objective of this study was to assess obstetrical complications and neonatal outcomes in women with endometriosis as compared with women without endometriosis. Material and methods: National cohort including all delivering women and their newborns in Denmark 1997–2014. Data were extracted from the Danish Health Register and the Medical Birth Register. Logistic regression analysis provided odds ratios (OR) with 95% confidence intervals (CI). Sub-analyses were made for primiparous women with a singleton pregnancy and for women with endometriosis who underwent gynecological surgery before pregnancy. Results: In 19 331 deliveries, women with endometriosis had a higher risk of severe preeclampsia (OR 1.7, 95% CI 1.5–2.0), hemorrhage in pregnancy (OR 2.3, 95% CI 2.0–2.5), placental abruption (OR 2.0, 95% CI 1.7–2.3), placenta previa (OR 3.9, 95% CI 3.5–4.3), premature rupture of membranes (OR 1.7, 95% CI 1.5–1.8), and retained placenta (OR 3.1, 95% CI 1.4–6.6). The neonates had increased risks of preterm birth before 28 weeks (OR 3.1, 95% CI 2.7–3.6), being small for gestational age (OR 1.5, 95% CI 1.4–1.6), being diagnosed with congenital malformations (OR 1.3, 95% CI 1.3–1.4), and neonatal death (OR 1.8, 95% CI 1.4–2.1). Results were similar in primiparous women with a singleton pregnancy. Gynecological surgery for endometriosis before pregnancy carried a further increased risk. Conclusion: Women with endometriosis had a significantly higher risk of several complications, such as preeclampsia and placental complications in pregnancy and at delivery. The newborns had increased risk of being delivered preterm, having congenital malformations, and having a higher neonatal death rate. Pregnant women with endometriosis require increased antenatal surveillance.