Associations among body size across the life course, adult height and endometriosis

STUDY QUESTION: Are body size across the life course and adult height associated with endometriosis? SUMMARY ANSWER: Endometriosis is associated with lean body size during childhood, adolescence and adulthood; tall total adult height; and tall sitting height. WHAT IS KNOWN ALREADY: The literature suggests that both adult body size and height are associated with endometriosis risk, but few studies have investigated the role of body size across the life course. Additionally, no study has investigated the relationships between components of height and endometriosis. STUDY DESIGN, SIZE, DURATION: We used a nested case-control design within E3N (Etude Epidemiologique aupres de femmes de l'Education Nationale), a prospective cohort of French women. Data were updated every 2-3 years through self-administered questionnaires. Odds ratios (ORs) and 95% CIs were computed using logistic regression models adjusted for a priori confounding factors. PARTICIPANTS/MATERIALS, SETTING, METHODS: A total of 2416 endometriosis cases were reported as surgically ascertained among the 61 208 included women. MAIN RESULTS AND THE ROLE OF CHANCE: The odds of endometriosis were lower among women who reported having a large versus lean body size at 8 years (P for trend = 0.003), at menarche (P for trend < 0.0001) and at ages 20-25 years (P for trend < 0.0001). Women in the highest quartiles of height had statistically significantly increased odds of endometriosis compared to those in the lowest (< 158 cm) (162-164 cm: OR = 1.28, 95% CI = 1.12-1.46; >= 165 cm: OR = 1.33, 95% CI = 1.18-1.49, P for trend < 0.0001). Statistically significantly increased odds were also observed among women with a taller sitting height (OR = 1.24, 95% CI = 1.05-1.47, P for trend = 0.01). Leg length was not statistically significantly associated with endometriosis. LIMITATIONS REASONS FOR CAUTION: Endometriosis cases may be prone to misclassification; however, we restricted our case definition to surgically-confirmed cases, which showed a high validation rate. Body size is based on retrospective self-report, which may be subject to recall bias. WIDER IMPLICATIONS OF THE FINDINGS: The results of this study suggest that endometriosis is positively associated with lean body size across the life course and total adult height. They also suggest that components of height are associated with endometriosis, which should be investigated further.