Association of uterine fibroids with late miscarriage: multicenter cohort study.

OBJECTIVE

To investigate the correlation between the number, location and size of uterine fibroids and the incidence of late miscarriage during pregnancy.

METHODS

This was a retrospective, multicenter cohort study of singleton pregnancies, with a live fetus at the first-trimester ultrasound examination, without known genetic anomalies or major fetal defects, from January 2012 to December 2022. We assessed the impact of fibroids and their characteristics, identified on ultrasound imaging at 11 + 0 to 13 + 6 weeks, on the risk of late miscarriage occurring at 11 + 0 to 21 + 6 weeks. Fibroid number, location and size were investigated, and adjusted odds ratios (aORs) with 95% CIs were calculated using multiple logistic regression and propensity score analysis via inverse probability of treatment weighting (IPTW) to minimize confounding. Singleton pregnancies without uterine fibroids comprised the control group. We further calculated the adjusted absolute risk (aAR) for the control group and the adjusted risk differences (aRD) for the study groups.

RESULTS

In total, 31 355 singleton pregnancies were analyzed, of which 942 (3.0%) had uterine fibroids. Multiple logistic regression analysis showed that pregnancies with a single fibroid did not have higher odds for late miscarriage compared to those without fibroids (aOR, 1.2 (95% CI, 0.6-2.4)), but women with multiple fibroids did have higher odds of late miscarriage (aOR, 2.5 (95% CI, 1.0-6.2)). Similarly, multiple logistic regression analysis after IPTW did not find higher odds of late miscarriage in pregnancies with a single fibroid (aOR, 1.7 (95% CI, 0.9-3.0) and aRD, 0.7% (95% CI, -0.2 to 2.1%)) but revealed increased odds of late miscarriage in women with multiple fibroids (aOR, 2.9 (95% CI, 1.1-7.3) and aRD, 2.0% (95% CI, -0.6 to 9.7%)). Analysis of the location of single fibroids revealed that submucosal fibroids significantly increased the odds of late miscarriage by 4.7 times, while the presence of fibroids in other locations did not have a statistically significant association with late miscarriage. When we limited our study population to cases with submucosal and intramural fibroids, logistic regression showed no significant increase in the odds of miscarriage for a single fibroid (aOR, 1.8 (95% CI, 0.9-3.5) and aRD, 1.2% (95% CI, -0.1 to 3.1%)), but revealed significantly higher odds for multiple fibroids (aOR, 3.8 (95% CI, 1.4-10.6) and aRD, 5.1% (95% CI, 0.6-22.0%)) compared with controls. IPTW analysis found a 2.3-fold increase in the odds of late miscarriage for a single fibroid (aOR, 2.3 (95% CI, 1.2-4.2)) and an even larger increase in the odds of late miscarriage for multiple fibroids (aOR, 5.7 (95% CI, 2.2-15.1)).

CONCLUSION

Uterine fibroids are associated with increased odds of late miscarriage, particularly when they are multiple and submucosal. © 2025 International Society of Ultrasound in Obstetrics and Gynecology.