(1058) Uterine fibroid location and risk for preterm delivery

We sought to identify the impact of uterine fibroids on preterm delivery (PTD) in a large national cohort. We further evaluated the impact of fibroid location (intramural, submucosal, or subserosal) on PTD.

Study Design:

This was a retrospective cohort study of pregnant subjects from the National Inpatient Sample database through the HCUP-AHRQ who delivered from 2017 to 2019. Women were separated into groups based on presence or absence of fibroids. Rates of PTD at gestational age (GA) < 37 weeks, < 34 weeks, < 28 weeks and < 24 weeks were assessed. PTD rates were further evaluated by fibroid location and compared to those without fibroids. Student’s t-tests, ANOVA, chi-squared and logistic regression were used for statistical analysis and p-value < 0.05 was considered significant.

Results:

Greater than 2.1 million subjects were included in the analysis. Among these, 32,702 (1.5%) subjects had a diagnosis of uterine fibroids, with 27.1% identified as intramural, 7.5% submucosal, and 65.4% subserosal. Those with fibroids were more likely to be older, non-Hispanic black, privately insured, obese, in the top quartile of income, and have a prior c-section. PTD was higher in those with fibroids at all GA cutoffs: 13.3% versus 20.1% for < 37 weeks, 5.7% vs 10.1% at < 34 weeks, 2.4% vs 4.5% at < 28 weeks, and 1.4% vs 2.2% at < 24 weeks (p< 0.001). These findings persisted after controlling for confounders as those with fibroids experienced higher rates of PTD at < 37 weeks (aOR 1.45, 95%CI 1.41-1.49), < 34 weeks (aOR 1.61, 95%CI 1.54-1.67), < 28 weeks (aOR 1.70, 95% CI 1.61-1.80) and < 24 weeks (aOR 1.41, 95% CI 1.30-1.53). Intramural and submucosal fibroid location were both significantly associated with PTD at all GA cutoffs except < 24 weeks after controlling for confounders.

Conclusion:

Uterine fibroids are associated with increased odds of preterm delivery, particularly when located intramural or submucosal.