TRANSFERRING MORE EMBRYOS INCREASES RISK OF HETEROTOPIC PREGNANCY

Objectives: To analyze symptoms and signs that may distinguish heterot opic pregnancy from solely ectopic pregnancy (EP) after IVF. To determ ine if the number of embryos transferred is a risk factor for heteroto pic compared with solely EP. Design: Retrospective cohort of 587 IVF p regnancies, 328 with distorted tubal anatomy. Setting: University Hosp ital, London, a referral center for Ontario provincial government-supp orted assisted reproductive technologies. Participants: Couples underg oing IVF. Intervention: None. Main Outcome Measures: Heterotopic pregn ancy, solely EP, intrauterine pregnancy, and distorted pelvic anatomy. Results: Of 587 pregnancies, 7 were heterotopic pregnancies and 24 we re solely EP, all in the subset of 328 women with distorted tubal anat omy. Symptoms, signs, and time of diagnosis were not different between heterotopic and solely ectopic gestations. Compared with solely EP, h eterotopic pregnancies were associated with transfer of more embryos. With four or more embryos transferred, the odds ratio for development of heterotopic versus solely ectopic gestation was 10.0. Conclusion: H eterotopic pregnancy occurred in 2% of gestations after IVF, all in wo men with distorted tubal anatomy. Transfer of four or more embryos was a risk factor for heterotopic pregnancy.