Prevalence of uterine leiomyomas in the first trimester of pregnancy: an ultrasound-screening study

Abstract

Objective: To estimate the proportion of pregnant women with one or more leiomyomas detected by research-quality ultrasound screening in the first trimester, to describe the size and location of leiomyomas identified, and to report variation in prevalence by race/ethnicity.

Methods: Within an ongoing prospective cohort, we conducted 4,271 first-trimester or postmiscarriage ultrasound examinations. Sonographers measured each leiomyoma three separate times, recording the maximum diameter in three perpendicular planes each time. Sonographers and investigators classified type and location.

Results: Among 458 women with one or more leiomyomas (prevalence 10.7%), we identified a total of 687 leiomyomas. The mean size of the largest leiomyoma was 2.3 cm (95% confidence interval [CI] 1.8-2.8). Mean gestational age at ultrasonography was 61+/-13 days from last menstrual period. Prevalence varied by race/ethnicity: 18% in African-American women (95% CI 13-25), 8% in white women (95% CI 7-11), and 10% in Hispanic women (95% CI 5-19). The proportion of women with leiomyomas increased with age much more steeply for African-American women than for white women.

Conclusion: Leiomyomas are common in pregnancy and occur more often among African-American women. Given the limited research on effects of leiomyomas on reproductive outcomes, the degree to which race/ethnic disparities in prevalence of leiomyomas may contribute to disparities in events such as miscarriage and preterm birth warrants investigation.

Figure 1. Prevalence of Uterine Leiomyomas among Black (n=915) and White Women (n=2826)*†

*Prevalence is for 2-year age intervals (18= 17 and 18 year olds, 20= 19 and 20 year olds, etc). †Sample size was too small for evaluation of prevalence by age in other race/ethnic categories because there were fewer than five participants per cell in some cells.

Figure 2. Percentage of Women with More Than One Leiomyoma among Those with Leiomyomas

†Sample size was too small for evaluation of prevalence by age in other race/ethnic categories because there were fewer than five participants per cell in some cells.