Is neonatal uterine bleeding responsible for early-onset endometriosis?

Is Neonatal Uterine Bleeding Involved in Early-Onset Endometriosis?

BACKGROUND

There has been considerable progress in our understanding of endometriosis, but its pathophysiology remains uncertain. Uncovering the underlying mechanism of the rare instances of endometriosis reported in early postmenarcheal years and in girls before menarche can have wide implications.

METHODS

We conducted a literature review of all relevant articles on Medline.

RESULTS

In the review, we explore the pathogenetic theories of premenarcheal endometriosis, the role of retrograde menstruation in the adult and its potential role in early-onset disease, as well as the factors that argue against the existence of a link between early-onset endometriosis (EOE) and neonatal uterine bleeding (NUB).

CONCLUSIONS

As with endometriosis in adult women, the pathogenesis of early-onset disease remains unclear. A link between NUB and EOE is plausible, but there are considerable challenges to collating supporting evidence. The state of our understanding of early uterine development and of the pathophysiology of NUB leaves many unknowns that need exploration. These include proof of the existence of viable endometrial cells or endometrial mesenchymal stem cells in NUB, their passage to the pelvic cavity, their possible response to steroids, and whether they can reside within the pelvic cavity and remain dormant till menarche.

Neonatal uterine bleeding: Risk factors and its association with endometriosis-related symptoms later in life

OBJECTIVE

We examined the prevalence and risk factors in association with neonatal uterine bleeding (NUB) by retrospective search of contemporary and historical medical records and investigated the possible association between the history of NUB at birth and endometriosis-related symptoms later in life who are now young women.

STUDY DESIGN

This was a retrospective case-controlled cohort study and prospective evaluation of web-based questionnaire survey on symptoms related to endometriosis among young women born with and without NUB. Multiple regression analysis was performed incorporating various confounding variables that may influence the occurrence of NUB or the reporting of endometriosis symptoms later in life.

RESULTS

Among the 1093 female neonates born between 1996 and 2000, 105 of them had NUB, yielding with a prevalence of 9.6 %. Of the 807 female babies born between 2013 and 2017, 25 (3.1 %) had NUB. Multiple Logistic regression analysis indicated that younger age of the mother [odds ratio (OR) = 0.92, 95 % confidence interval (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 of ≥ 40 weeks (OR = 4.54, 95 % CI = 2.20-9.39, P < 0.0001) of gestation were significantly associated with the occurrence of NUB. While the possibility of recall bias cannot be ruled out, newborn females who had a history of NUB appeared to complain of various endometriosis-related symptoms later in life during adulthood.

CONCLUSIONS

We confirmed the validity of the reported prevalence and risk factors of NUB. NUB indeed occurs with a prevalence of 3-10% during the historical and contemporary period. Longer gestational age and younger maternal age may be considered as high-risk factors for the occurrence of NUB. The clinical relevance of our findings remains to be elucidated. Future prospective studies, preferably with larger sample sizes and the inclusion of NUB cases after discharge from the hospital, may further illuminate some unresolved issues. We also need to confirm the endometriosis-related symptoms in women with and without history of NUB via more definitive diagnosis such as imaging and histology.