The impact of fibroid characteristics on pregnancy outcome.

Objective: The objective of the study was to assess the influence of different characteristics of fibroids on pregnancy outcome.

Study Design: We identified women with fibroids 4 cm or greater in size on ultrasonography at the dating scan between January 2002 and December 2012. The size (4-7 cm, 7-10 cm, >10 cm), number (multiple/single), location (lower uterus/body of uterus), and type (intramural, combination of intramural/subserosal, subserosal) were ascertained. Medical records were reviewed to obtain pregnancy outcomes (preterm delivery, birthweight, mode of delivery, estimated blood loss, postpartum hemorrhage, and admission for fibroid-related pain).

Results: A total of 121 patients with 179 pregnancies were identified. Preterm delivery was more likely in those with multiple fibroids compared with single fibroids (18% vs 6%; P = .05). The location of the fibroid had an important effect on the mode of delivery with a higher cesarean section rate for fibroids in the lower part of uterus than in the body of the uterus (86% vs 40%; P = .01), a higher rate of postpartum hemorrhage (22% vs 11%; P = .03), and greater estimated blood loss (830 mL [SD, 551] vs 573 mL [SD, 383]; P = .03). Increasing size of fibroid was associated with greater rates of hemorrhage (11% vs 13% vs 36%; P = .04), increased estimated blood loss (567 mL [SD, 365] vs 643 mL [SD, 365] vs 961 mL [SD, 764]; P = .01), and higher rates of admissions for fibroid-related pain (5% vs 23% vs 21%; P = .01).

Conclusion: Different fibroid characteristics affect pregnancy outcome in varying ways. This information can be used to aid counseling women antenatally and in risk-stratifying patients.