Uterine Fibroids in Pregnancy: Not So Benign?

Summary and Comment |
November 18, 2010

Uterine Fibroids in Pregnancy: Not So Benign?

  1. Allison Bryant, MD, MPH

Pregnant women with uterine fibroids were at risk for a host of adverse obstetric outcomes.

  1. Allison Bryant, MD, MPH

Uterine fibroids (leiomyomas) are common among women of reproductive age, but data about obstetric outcomes associated with fibroids are conflicting. Investigators conducted a large retrospective cohort study to characterize better the obstetric risks associated with these pathologically benign tumors. Of 64,000 women with complete obstetric follow-up at a single U.S. university institution, fibroids were identified in more than 2000 (3.2%) at routine second-trimester ultrasound examination. Demographic information and data on pregnancy and delivery outcomes were compared in women with versus without fibroids.

Compared with women who did not have fibroids, those who did were more likely to be older (mean age, 35 vs. 30), to be black, to report vaginal bleeding during pregnancy, and to have histories of diabetes and hypertension. In adjusted analyses, presence of uterine fibroids during the second trimester was associated with excess risk for breech presentation at delivery (adjusted odds ratio, 1.5), placenta previa (AOR, 2.2), placental abruption (AOR, 2.1), and cesarean delivery (AOR, 1.2 even after excluding pregnancies with placenta previa and breech presentation). Women with fibroids were more likely to deliver early (i.e., at <37 weeks or <34 weeks). In addition, risk for intrauterine fetal death was higher among women with fibroids, particularly when intrauterine growth restriction was diagnosed. Although number of fibroids did not seem to influence outcomes, fibroids >5 cm were associated with higher risks for adverse outcomes.


Clinicians are often reassuring in their counseling of women with uterine fibroids during pregnancy, although these findings might argue for a more-stringent approach. Patients and providers alike should be made aware of the associations with adverse outcomes, particularly excess risk for bleeding complications, preterm birth, and fetal demise. The results also raise the question of whether disparities in birth outcomes might be related, in part, to differential prevalence of uterine fibroids in certain demographic populations (e.g., black women). Whether more antenatal fetal surveillance with ultrasound or other means is warranted when fibroids are present is an open question that merits more study.


Reader Comments (3)

Janice M Pelletier

I believe this article is alarming and is limiting in its scope of study material. The population is biased to black women, with little reference to white women. There is no reference to the positioning of the fibroid itself, which is relevant to the outcome. Get all the material, then publish an article! I do not believe the information presented was formatted with enough information to make the stated premise.

Competing interests: None declared

Helen A. Toews

Article is clear and well written. It points out the probability that fibroids in pregnancy , deserve more attention than usually given.

Competing interests: None declared

William H. Parker

The headline of this review makes it sound like fibroids commonly cause problems in pregnancy. The facts of the study, expressed as absolute risks, suggest otherwise:

The study found a 0.9% increased risk of placenta previa; a 0.7% increased risk of placental abruption; a 0.9% increased risk of premature ruptured membranes; a 1.1% increased risk of delivery before 34 weeks; and, a 1.4% increased risk of fetal death only in growth restricted babies. This study was conducted at an urban referral hospital and women had a high rate of alcohol use, smoking and high blood pressure, so the results might be even better in a healthier group of women.

Two other well-conducted studies have been published previously on this topic: one showed no increased risk of pregnancy complications for women with fibroids; the other showed very minimal increased risks. (1, 2)

I do not disagree that whether “more antenatal fetal surveillance with ultrasound or other means is warranted when fibroids are present is an open question that merits more study”, but I think the data are reassuring.

(1) Vergani P, Am J Perinatol, 1994;11:356 (2) Qidawi G, Obstet Gynecol 2006;107:376

Competing interests: None declared

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