Background: In young men, high body mass index (BMI) has been linked to liver disease later in life, but it is unclear if this also applies to women. Aim: To study the association between BMI early in life and development of liver disease later in life in women. Methods: We obtained data on early pregnancy BMI from 1 139 458 Swedish women between 1992 and 2015. National registers were used to ascertain incident severe liver disease, defined as cirrhosis, decompensated liver disease (hepatocellular carcinoma, oesophageal varices, hepatorenal syndrome or hepatic encephalopathy) or liver failure. A Cox regression model was used to investigate associations of BMI with incident severe liver disease adjusting for maternal age, calendar year, country of birth, smoking, civil status and education. Results: During an average follow-up of 13.8 years, 774 women developed severe liver disease. Compared to women with a low normal BMI (18.5-22.4), an increased risk of severe liver disease was found in women with BMI between 22.5 and 24.9 kg/m2 (adjusted hazard ratio [aHR] 1.25, 95% CI 1.04-1.50), 25.0 and 29.9 kg/m2 (aHR 1.27, 95% CI 1.05-1.53) and BMI ≥ 30 kg/m2 (aHR 1.77, 95% CI 1.40-2.24). When examining BMI as a continuous variable, the aHR increased by 4% per kg/m2 (95% CI 1.02-1.05). A diagnosis of diabetes was associated with an increased risk of severe liver disease independent of baseline BMI. Conclusion: A high BMI early in life in women is associated with a dose-dependent, increased risk for future severe liver disease.