Non-visualized pregnancy losses are prognostically important for unexplained recurrent miscarriage.

Area of Science:

• Reproductive Medicine
• Obstetrics and Gynecology
• Clinical Epidemiology

Background:

• Recurrent miscarriage (RM) significantly impacts live birth chances.
• Clinical miscarriages are known determinants of live birth outcomes in RM.
• The prognostic significance of non-visualized pregnancy losses in RM remains largely unknown.

Purpose of the Study:

• To investigate the association between non-visualized pregnancy losses in reproductive history and the likelihood of live birth in subsequent pregnancies among women with unexplained RM.
• To determine if non-visualized pregnancy losses have a negative prognostic impact on live birth rates in women experiencing recurrent miscarriage.

Main Methods:

• Retrospective cohort study of 587 women with unexplained RM evaluated between 2000-2010.
• Analysis of pregnancy outcomes for 499 women following referral.
• Poisson regression analysis was used to calculate the relative risk (RR) of live birth, adjusting for known risk factors.

Main Results:

• Non-visualized pregnancy losses accounted for 37% of prior pregnancies in the study cohort.
• Each non-visualized pregnancy loss conferred a reduced relative risk (RR) of 0.90 for live birth, comparable to clinical miscarriages (RR 0.87).
• Women with ≥2 clinical miscarriages showed reduced live birth RRs for both clinical (0.82) and non-visualized losses (0.89).

Conclusions:

• Non-visualized pregnancy losses (biochemical pregnancy loss and failed pregnancy of unknown location) are clinically significant and negatively impact the chance of live birth in women with unexplained RM.
• These findings highlight the importance of considering all types of pregnancy losses when assessing prognosis in women with recurrent miscarriage.
• The study suggests that interventions aimed at improving live birth rates in RM should also address the impact of non-visualized pregnancy losses.