A comparison of heterotopic and intrauterine-only pregnancy outcomes after assisted reproductive technologies in the United States from 1999 to 2002.

Objective: To compare the risk for adverse outcomes of pregnancies between heterotopic (defined as a simultaneous intrauterine and ectopic pregnancy) and intrauterine-only pregnancies achieved through assisted reproductive technologies (ARTs).
Design: Retrospective cohort study.
Setting: ART centers in the United States.
Patient(s): Patients were studied in terms of cycles reported to the population-based United States ART Registry, which included 207 heterotopic and 132,660 intrauterine-only pregnancies reported from 1999 to 2002.
Intervention(s): None.
Main Outcome Measure(s): Outcomes of heterotopic and intrauterine-only pregnancies and deliveries (spontaneous abortion, induced abortion, still birth, and live birth). Perinatal outcomes (preterm, low birth weight [LBW], preterm LBW, and term LBW) for live-birth deliveries were also assessed.
Result(s): Heterotopic pregnancies were more likely to end in spontaneous (relative risk = 2.05; 95% confidence interval, 1.67-2.51) or induced (relative risk = 10.28, 95% confidence interval, 6.76-15.65) abortions than were intrauterine-only pregnancies. There was no significant difference in perinatal outcomes studied, regardless of adjustment for maternal age, infertility diagnosis, previous live births, and type of ART procedure.
Conclusion(s): Heterotopic pregnancies were more likely to result in spontaneous or induced abortions than were intrauterine-only pregnancies. There was no difference in perinatal outcomes between heterotopic and intrauterine-only pregnancies progressing to live birth.