**Background:** The Lifelines Reproductive Origins of Adult Health and Disease (Lifelines-ROAHD) cohort was designed to investigate the role of reproduction-related determinants of health and disease, building on the concept that early-life development, starting before conception, influences future health. Embedded within the larger population-based Lifelines cohort study (over 167,000 participants in the Northern Netherlands), this sub-cohort aims to facilitate research on menstrual health, fertility, pregnancy progress and outcomes, birth experiences, and health outcomes for mothers and children.
**Methods:** Women of reproductive age (20–45 years) who were already participating in the Lifelines cohort were invited to complete an online questionnaire between September 2017 and March 2018. Of 30,712 eligible women, 5,933 (19.3%) at least partly completed the questionnaire. After exclusions (310 with incomplete essential data, 132 with multiple pregnancies and excessive missing values, 79 with unknown child birth year), 5,412 women were included. The questionnaire covered: (1) women's health (menstrual cycle, menopause, contraceptive use); (2) reproductive health (fertility problems, assisted reproductive treatments, sexually transmitted diseases, family planning); (3) for each experienced pregnancy (conception, medication, lifestyle, complications, outcomes); (4) for each birth ≥25 weeks gestation (onset of delivery, pain relief, mode of birth, place of birth, adverse maternal outcomes, birth outcomes, infant characteristics); and (5) for the most recent pregnancy (work characteristics, exposures, postpartum physical/psychological/sexual health). The validated Dutch version of the Childbirth Experience Questionnaire 2.0 (CEQ2.0) was also administered. Descriptive statistics were used to characterize the cohort.
**Key Results:** Among 5,412 women (born 1971–1995), 48.1% had never been pregnant and 51.9% had experienced at least one pregnancy. The majority were of Dutch origin (97.2%) with middle or high education (86.5%). Regarding menstrual health, 45.6% had a natural cycle, 30.9% used hormonal contraceptives, and 23.6% had no cycle for various reasons. Fertility consultation occurred in 908 women (16.8%), with diagnosed problems including anovulation (24.4%), male partner infertility (22.5%), unexplained infertility (22.2%), and PCOS (8.1%). Assisted reproductive treatments included ovulation induction (19.8%), IUI (26.9%), IVF (13.0%), and ICSI (16.4%).
In total, 2,808 women experienced 6,158 pregnancies (range 1–9). Most were naturally conceived (89.2%), planned and wanted (87.0%), and achieved within 0–3 months (47.7%). Folic acid use was reported for 62.9% of pregnancies. Smoking during pregnancy occurred in 7.3% (any duration) and alcohol in 5.9%. Pregnancy outcomes before 25 weeks included miscarriage (14.3%), ectopic pregnancy (0.9%), and termination or medical abortion (2.0%). Miscarriage rates increased from 13.9% in first pregnancies to 19.9% in fourth pregnancies.
Among 5,068 births, maternal complications included hypertension (11.2%), urine tract infections (4.9%), preeclampsia/HELLP (3.3%), and diabetes gravidarum (2.6%). Onset of delivery was spontaneous in 73.6%, with 28.4% of births occurring at home. Mode of birth was vaginal (74.9%), instrumental vaginal (11.9%), elective caesarean (3.9%), and emergency caesarean (9.3%). Episiotomy was performed in 40.1% of vaginal births. Birth outcomes showed 93.6% born alive at term, 5.8% born alive preterm, stillbirth in 0.316%, and neonatal death in 0.197%. Most infants (83.5%) weighed ≥3,000 g, 86.9% had skin-to-skin contact within one hour, and 71.5% started breastfeeding within one hour.
One year postpartum, adverse physical health ranged from 0.5% (faecal incontinence) to 12.5% (urine incontinence), psychological issues from 0.7% (PTSD) to 1.6% (depression), and diminished sexual health was reported by 1.6%. The mean CEQ2.0 score (n=1,742) was 3.2 (SD 0.5), with first-birth women scoring lower across all subscales compared to women with subsequent births.
**Clinical Implications:** The Lifelines-ROAHD cohort provides a uniquely detailed dataset covering the full spectrum of reproductive health—from menstruation and fertility through pregnancy, childbirth, and postpartum health—within a defined geographic population. The embedded nature within the Lifelines cohort allows for prospective follow-up and linkage to extensive phenotyping data, biobank samples, and registries (e.g., Statistics Netherlands, prescription medication database). This will enable investigations into determinants of reproductive health and the long-term impact of reproductive events on chronic disease risk for both mothers and children. The cohort's findings can inform clinical counselling, public health policy, and future research priorities in reproductive medicine and epidemiology.