Women's Health

September 30, 2021

Fibroids and preterm birth

In a large, prospective study, Vanderbilt researchers found no association between fibroids and any clinical subtype of preterm birth, supporting a reconsideration of the impression that fibroids increase preterm birth risk.

Uterine fibroids — muscular tumors that grow in the uterus — are inconsistently linked with preterm birth. Katherine Hartmann, MD, PhD, and colleagues sought to determine the association between fibroids and preterm birth by using ultrasounds early in pregnancy. 

Women who were pregnant or planning a pregnancy were recruited to participate and had an ultrasound in the first trimester to record information about the presence, size, number and location of fibroids. Birth outcomes, including preterm labor, preterm premature rupture of membranes and medically indicated preterm birth were cross validated from labor and delivery records. 

As reported in BMC Pregnancy and Childbirth, out of 4,622 women with singleton pregnancies, 475 had at least one fibroid (10.3%) and 352 pregnancies resulted in preterm birth (7.6%). Prevalence of fibroids was similar for women with preterm and term births (10.2% vs. 10.3%). 

The researchers concluded that if fibroids increase risk of preterm birth, the effect is substantially smaller than previous estimates.

Other authors of the study include Alexandra Sundermann, MD, PhD, Tiara Aldridge, MD, Sarah Jones, Eric Torstenson and Digna Velez-Edwards, PhD. The research was supported by the National Institutes of Health (grants HD094345, HD043883, HD049675, GM007347, TR000445) and the American Water Works Association Research Foundation.