PURPOSE: The Lifelines Reproductive Origins of Adult Health and Disease (Lifelines-ROAHD) cohort provides a uniquely detailed dataset allowing investigations of determinants of reproductive health as well as the influence of reproductive events on future health and disease of mother and child(ren). Lifelines-ROAHD cohort is embedded in the population-based Lifelines cohort study. PARTICIPANTS: In total, 5412 women of reproductive age (20-45 years) were included in the Lifelines-ROAHD cohort, in the period 2017-2018. FINDINGS TO DATE: In the population, 45.6% of the women indicated that they had a natural menstrual cycle. In total, 908 women (16.8%) consulted a healthcare provider for infertility; subsequently diagnosed fertility problems were anovulation (24.4%), male partner infertility problems (22.5%) or unexplained infertility (22.2%). Women underwent various consecutive assisted reproductive treatments, for example, ovulation induction (19.8%) or in vitro fertilisation (5.4%). In total, 2808 women experienced 6158 pregnancies and 5068 births. Adverse pregnancy outcomes were miscarriage (14.3%), ectopic pregnancy (0.9%) or termination of pregnancy or medical abortion (2.0 %). The modes of delivery were vaginal births (74.9%), instrumental vaginal births (11.9%), elective caesarean section (3.9%) and emergency caesarean section (9.3%). Birth outcomes were born alive at term (93.6%), born alive (very) pre-term (5.8%), stillbirth (0.316%) and neonatal death (0.197%). Additional data about 2660 most recent pregnancies showed that 19.9% of the women had irregular working hours. One year postpartum, women indicated adverse physical health issues in one or more domains, range 0.5%-12.5%. They also indicated adverse psychological health issues in one or more domains, range 0.7%-1.6%, and 1.6% experienced diminished sexual health. FUTURE PLANS: Due to the embedding of Lifelines-ROAHD cohort in the original Lifelines cohort, the women will be longitudinally followed. Additionally, we aim to collect data with a second ...