Increased risk of preterm births among women with uterine leiomyoma: a nationwide population-based study.

BACKGROUND: Using a 3-year nationwide population-based database, this study examines the risk of adverse pregnancy outcomes [lower birthweight, preterm gestation and babies small for gestational age (SGA)] in pregnant women with uterine leiomyoma.

METHODS: This study linked two data sets: Taiwan's birth certificate registry and its National Health Insurance Research Data set. A total of 5627 mothers with uterine leiomyoma and 28 135 unaffected mothers were included for analysis. After adjusting for mother and infant characteristics and monthly family income, log-binominal regression and multivariate regression analyses were conducted to examine the risks of preterm birth, SGA and lower birthweight among mothers with uterine leiomyoma and unaffected mothers.

RESULTS: Women with uterine leiomyoma had a significantly higher percentage of preterm births (10.98 versus 7.78%, P < 0.001) and SGA infants (19.00 versus 17.28%, P = 0.002) than unaffected mothers. The mean birthweights for mothers with and without uterine leiomyoma were 3083 and 3172 g, respectively (P < 0.001). Log-binominal regression models show that the adjusted risk ratios of preterm births and SGA infants for mothers with uterine leiomyoma were 1.32 (95% CI 1.19-1.46) and 1.16 (95% CI 1.08-1.26), respectively, compared with unaffected mothers. After finally adjusting for gestational age and other covariates, a multivariate regression analysis revealed that women with uterine leiomyoma had, on average, a 14.7 g lower birthweight than unaffected mothers (P = 0.022).

CONCLUSIONS: We concluded that after adjusting for potential confounders, women with uterine leiomyoma experience a small yet significant increased risk of preterm and SGA infants. We suggest that clinicians intensively monitor women with uterine leiomyoma during pregnancy.