Outcomes in pregnancy with uterine fibroids

The size of the uterine fibroids, and not their number, increases the risks for adverse pregnancy and obstetric outcomes including breech presentation, postpartum hemorrhage and placenta previa, according to a recent study published in the journal BMC Pregnancy and Childbirth.1

This meta-analysis was conducted to ascertain the impact of uterine fibroids on adverse consequences, with particular focus on the multiple or big fibroids measuring ≥5 cm in size. Li and colleagues looked through the databases of PubMed, Embase, Web of Science, ClinicalTrials.gov, China National Knowledge Infrastructure (CNKI), and SinoMed to find relevant research on the impact of uterine fibroids on unfavorable pregnancy outcomes. Twenty-four studies with a total of 237 509 participants were included in the analysis.

Pooled analysis revealed that uterine fibroids significantly increased the risks of a number of unfavorable pregnancy and obstetric outcomes, such as low birth weight (relative risk [RR] 1.72), breech presentation (RR 2.26), preterm birth (RR 1.72), placenta previa (RR 2.99), miscarriage (RR 4.51), preterm premature rupture of membranes (PPROM) (RR 1.37), placental abruption (RR 1.85), postpartum hemorrhage (PPH) (RR 3.52), and fetal distress (RR 3.61).

Adverse effects, however, were only observed for preterm birth, cesarean delivery, placenta previa, placental abruption, PPH, intrauterine fetal mortality, breech presentation, and preeclampsia after correcting for the potential confounding factors.

A subgroup analysis further revealed that compared to smaller fibroids (less than 5 cm), larger fibroids (greater than 5 cm) significantly increased the risks for PPH (RR 5.04), breech presentation (RR 1.5) and placenta previa (RR 1.62).

The risk of breech presentation, placental abruption, cesarean delivery, PPH, placenta previa, PPROM, preterm birth, and intrauterine growth restriction (IUGR) was not increased by the presence of multiple fibroids. On meta-regression analysis, the relationship between uterine fibroids and intrauterine fetal death was influenced by BMI, while the association between uterine fibroids and preterm birth was solely impacted by the age of the mother. Outcomes such as malposition, fetal discomfort, placenta previa, placental abruption, PPROM, miscarriage and PPH were unaffected by other potential confounding factors.

These findings highlight the importance of considering individual factors like maternal age and BMI when assessing the risks associated with uterine fibroids in pregnancy. This helps in managing and counseling patients with uterine fibroids during pregnancy to diminish the impact of these risks. “Our results provide valuable information for the identification of the risks of breech presentation, postpartum hemorrhage and placenta previa,” write the authors.

Reference

1.   Hong Li, et al. The influence of uterine fibroids on adverse outcomes in pregnant women: a meta-analysis. BMC Pregnancy Childbirth. 2024 May 6;24(1):345. doi: 10.1186/s12884-024-06545-5.