Journal: Obstet Gynecol. 2010 Nov;116(5):1056-63.
Authors: Stout MJ, Odibo AO, Graseck AS, Macones GA, Crane JP, Cahill AG.
Study from: Washington University, St Louis, Missouri
Problem: Numerous studies have been conducted to see if the presence of fibroids during pregnancy affects the outcome of the pregnancy or the health of the baby. Most of these studies have been poorly designed and have failed to answer these important questions.
Study: Between 1990 and 2007, 64,047 consecutive pregnant women had a routine second-trimester ultrasound and the presence or absence of fibroids was routinely noted. The outcomes of the pregnancies in women with fibroids were compared to pregnancies in women without fibroids.
Results: Fibroids were seen on ultrasound in 3.2% of all pregnant women. The following findings were noted.
- Babies were breech in 5.3% of women with fibroids compared with 3.1% of women with no fibroids.
- Placenta previa (placenta partially or completely blocking the cervix) was found in 1.4% (fibroids) compared with 0.5% (no fibroids).
- Placental abruption (placenta separating from the uterine wall, causing bleeding) was found in 1.4% (fibroids) compared with 0.7% (no fibroids).
- Preterm rupture of membranes was found in 3.3% (fibroids) compared with 2.4% (no fibroids).
- Preterm birth less than 37 weeks was found in 15.1% (fibroids) compared with 10.5% (no fibroids) and at less than 34 weeks was 3.9% (fibroids) compared with 2.8% (no fibroids).
- Intrauterine fetal death in women with a baby with growth restriction (small baby) was found in 3.9% (fibroids) compared with 1.5% (no fibroids).
- Cesarean delivery was performed in 33% (fibroids) compared with 24% (no fibroids).
Authors’ Conclusions: Women with fibroids are at low risk for obstetric complications compared with women without fibroids.
Dr. Parker’s Comments: Two other excellent studies have been published previously on this topic: one showed absolutely no increased risk of complications for women who became pregnant with fibroids; the other showed very minimal increased risks.
This new study shows very minimal increased risks: a 0.9% increased risk of the placenta blocking the cervix; a 0.7% increased risk of placental separation; a 0.9% increased risk of early ruptured membranes; a 4.6% increased risk of delivery before 37 weeks (where the babies usually do extremely well) and a 1.1% increased risk of delivery before 34 weeks (most babies also do well, but need neonatal ICU care); and, a 1.4% increased risk of fetal death in babies who were very small at birth. The new study was conducted at an urban referral hospital and the 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.
The findings of the three well-performed studies show an extremely small increased risk, which ought to be reassuring for women with fibroids who wish to become pregnant. It should also be noted that, based on a review of the literature I did for a chapter on fibroids to be published in Berek and Novak’s Gynecology textbook, in the past 30 years there have been only four babies born in the world who have been reported to have birth defects related to the presence of fibroids during pregnancy. This is also very reassuring news.