Community-based ongoing study: small fibroids linked to early pregnancy loss; Interim results suggest fibroids < 3 cm in diameter may raise miscarriage risk fourfold.(News)

HOUSTON -- Fibroids so small they are ignored by the widely used Muram ultrasound criteria appear to have a profound association with spontaneous abortion, perhaps explaining many early pregnancy losses, especially among African American women.

Interim results of a community-based study reveal almost a fourfold risk of spontaneous abortion among women who were found to have fibroids measuring <3 cm in diameter during early pregnancy. In contrast, patients with fibroids> 3 cm in early pregnancy had no increased risk of a miscarriage.

"Perhaps our most intriguing finding is that small, entirely intramural fibroids with an average diameter of a centimeter or less may well turn out to be associated with some level of risk," study investigator Dr. Katherine E. Hartmann said at the annual meeting of the Society for Gynecologic Investigation.

If further study confirms that "jelly-bean-sized" fibroids can disrupt a pregnancy, "we [may] need to move beyond purely architectural explanations of how fibroids cause harm," said Dr. Hartmann of the University of North Carolina at Chapel Hill.

Previously, retrospective and case-control studies have supported a link between uterine fibroids and spontaneous abortion, but these generally did not include fibroids

Dr. Hartmann's findings are from the Right From the Start program, an ongoing prospective study of early pregnancy in Raleigh, N.C.; Galveston, Texas; and Memphis.

Women planning a pregnancy or in the early stages of gestation are recruited through private physicians' offices, advertisements, and coupons in pregnancy tests. The average gestational age at enrollment of the first 1,646 participants was 53 days, with those "preenrolling" before conception enrolling at an average of 31 days after their last menstrual period.