OBJECTIVE: The etiology of endometriosis is poorly known
established risk factors are limited and few environmental risk factors have been identified. We aimed to explore the associations between several perinatal and childhood environmental exposures and the risk of endometriosis/adenomyosis in women. METHODS: This study was based on NutriNet-Santé, an ongoing web-based prospective cohort following-up several tens of thousands of French adults since 2009. The analysis included 25,251 women with health data available who completed a self-administered questionnaire on perinatal and childhood exposures in 2019. Associations with self-reported endometriosis/adenomyosis were investigated using multivariable logistic regression models, adjusted for potential confounders identified through direct acyclic graphs. RESULTS: Among women, 1126 (4.5 %) self-reported a diagnosis of endometriosis/adenomyosis. Endometriosis/adenomyosis was positively associated with a low birth weight (<
2500 g vs. ≥2500 g: adjusted odds-ratio (aOR) = 1.43, 95 % confidence interval (95 % CI) = 1.03-2.00), exposure to maternal smoking during pregnancy (aOR = 1.86, 95 % CI = 1.33-2.61), daycare attendance (aOR = 1.61, 95 % CI = 1.11-2.33), exposure to pets in childhood (both cat and dog vs. no animals: aOR = 1.23, 95 % CI = 1.08-1.41), and mold exposure in housing during childhood (aOR = 1.42, 95 % CI = 1.15-1.74). Conversely, living on a farm during childhood (aOR = 0.77, 95 % CI = 0.62-0.97) and having farmer parents (aOR = 0.72, 95 % CI = 0.54-0.97) were inversely associated with endometriosis. Maternal age at birth, birth length, prematurity, mode of delivery, or exposure to breastfeeding was not associated with endometriosis/adenomyosis. CONCLUSION: Findings from this large population-based study among French adult women suggest associations between several perinatal and childhood exposures and endometriosis/adenomyosis. Research on early-life and childhood environments with endometriosis/adenomyosis might have important implications for the primary prevention of endometriosis and adenomyosis.