Leiomyomata uteri, genetic amniocentesis, and the risk of second-trimester spontaneous abortion

OBJECTIVE: The purpose of this study was to determine the impact of leiomyomata uteri on the risk of second-trimester spontaneous abortion and to determine whether genetic amniocentesis further increases this risk. STUDY DESIGN: We retrospectively identified pregnant women with leiomyomata uteri who underwent genetic amniocentesis (cases) at the University of Rochester and the Johns Hopkins Hospital between April 1994 and June 2000. Two control groups were also identified: (1) pregnant women without leiomyomata who had undergone genetic amniocentesis (amnio only) and (2) pregnant women at similar gestational ages with leiomyomata who had not undergone amniocentesis (myoma only). Cases and controls were matched for maternal age and parity. All subjects were then followed up to ascertain pregnancy outcomes. RESULTS: One hundred twenty-eight women with leiomyomata uteri who underwent genetic amniocentesis were identified and matched with 128 amnio-only controls and 128 myoma-only controls. The incidence of spontaneous abortion was 6.3% among the cases, 0.8% in the amnio-only controls, and 7.0% in the myoma-only controls. The relative risk (95% CI) for spontaneous abortion was 8.0 (1.02-63.04) for cases versus amnio only but was not significantly different from 1.0 for cases versus myoma-only controls. CONCLUSIONS: Women with leiomyomata are at an increased risk for second-trimester spontaneous abortion. Midtrimester amniocentesis does not appear to further increase this risk.