Pregnancy outcomes in a recurrent miscarriage population after common uterine surgeries: A multicentre cohort study
Charlotte Leeson MBBS a,b,c, Yealin Chung MBBS MRCOG d, Joshua Odendaal PhD MRCOG a,b,c, Christina Easter MSc e, Adam Devall PhD d, Siobhan Quenby PhD FRCOG a,b,c.
aTommy’s National Centre for Miscarriage Research, Coventry, CV2 2DX, UK. bUniversity Hospitals Coventry and Warwickshire NHS Trust, Coventry, CV2 2DX, UK. cUniversity of Warwick, Coventry, CV47AL, UK. dUniversity of Birmingham, Edgbaston, Birmingham, B152TT, UK. eInstitute of Applied Health Research, University of Birmingham, UK.
Introduction:
•Recurrent miscarriage affects 1–2% of reproductive-age couples, and latest ESHRE guidance calls for better patient information.
•Maternal age is strongly linked to chromosomally abnormal losses, especially over age 45; recurrent euploid losses are less well understood and may involve multiple risk factors.
•Intrauterine adhesions often follow uterine surgeries like curettage, occurring in up to 20% of cases after surgical management of miscarriage.
•Other surgical impacts on fertility include disruption of the endometrial microbiome and caesarean section niche formation.
•Women with multiple miscarriages are more likely to have had prior surgical interventions.
•Current UK guidance emphasises shared decision-making for miscarriage management (expectant, medical, or surgical), balancing risks and benefits.
•Surgical management achieves better complete evacuation rates but carries potential long-term risks, including adhesion formation.
•Cesarean sections may also contribute to future miscarriage risk, but current research is inconsistent and underpowered.
Aims:
•To identify if there is any association between method of miscarriage management and subsequent pregnancy outcome
•To understand if there is any link between previous caesarean section and subsequent pregnancy outcome
Methods:
•Prospective cohort study using Tommy’s Net
•Eligibility: Women aged over 18 with ≥2 previous pregnancy losses;
•Exposures: Primary — previous surgical management of miscarriage (SMM); Secondary — prior caesarean section (CS), both self-reported at baseline.
•Primary Outcome: Miscarriage in the first pregnancy post-registration; Secondary outcomes: stillbirth and live birth.
•Statistical Analysis: Poisson regression for; models adjusted for maternal age, BMI, smoking, and number of previous miscarriages.
•Subgroup Analysis: Examined miscarriage outcomes based on the number of previous SMMs and CS exposures.
•Missing Data: Addressed using multiple imputation as >10% of key variables were missing (mostly maternal BMI); complete case analysis used for sensitivity.
Results:
Primary Outcome:
•No clear association between SMM and miscarriage (RR 1.03, 95% CI 0.89–1.2, p=0.661).
•No clear association between CS and miscarriage (RR 1.17, 95% CI 0.95–1.4, p=0.138)
Subgroup Analysis:
•Three or more SMMs showed a higher risk of miscarriage (RR 1.5, 95% CI 1.2–1.8, p=0.001).
•In women with three or more baseline miscarriages, both ≥3 SMMs and any CS were associated with higher miscarriage risk.
Conclusions:
In women with two previous miscarriages:
•Exposure to CS or SMM has no effect on the risk of future miscarriage.
In women with three or more SMMs:
•There is a higher risk of subsequent miscarriage.
In women with a previous CS and three previous miscarriages:
•There is also a higher risk of subsequent miscarriage.
