Association between neonatal uterine bleeding and endometriosis-related symptoms later in life

Abstract Background: Neonatal uterine bleeding (NUB) is reported to be involved in early onset endometriosis. There is no information whether young women with a history of NUB may manifest various symptoms related to endometriosis. In the present study we investigated the possible association between NUB and endometriosis-related symptoms later in life who are now adults. Methods: This is a retrospective case-controlled cohort study and prospective evaluation of questionnaire-based symptoms related to endometriosis among young women born with and without NUB. The prevalence of NUB was calculated and multiple logistic regression analysis with variable confounding factors was conducted to identify risk factors of NUB. The results of web-based questionnaire survey were analyzed by continuous variables using Wilcoxon rank sum test and categorical variables using Fisher’s exact test to compare endometriosis-related symptoms. Results: Among 807 female babies born at our hospital between 2013 and 2017, NUB occurred in 25 cases with a prevalence of 3.1%. Twenty-five NUB cases showed overt bleeding 4.5±1.8 days after birth (median 4 days, range 1-8 days) and it lasted for 1.4±0.8 days (median 1 day, range 1-4 days). Multiple logistic regression analysis indicated that younger age of the mother ((OR, 0.92, 95% CI 0.85-1.00, P=0.048)) and longer gestational age of 39 weeks (OR 3.04, 95% CI 1.43-6.45, P=0.004) and ≥40 weeks (OR 4.54, 95% CI 2.20-9.39, P<0.0001) of gestation were significantly associated with the occurrence of NUB. Young women with or without a history of NUB during the period of 1996-2000 manifested various endometriosis-related symptoms.Conclusion: We confirmed the validity of the reported prevalence and risk factors of NUB. Young mothers and longer gestational age are the risk factors of NUB and newborn females with or without NUB similarly suffer from various endometriosis-related symptoms later in life. Future prospective cross-sectional study is warranted to confirm the endometriosis-related symptoms in NUB+ cases by physical examination/ultrasound/MRI or laparoscopy. Trial registration: not applicable