Risk of ectopic pregnancy associated with assisted reproductive technology in the United States, 2001-2011.

OBJECTIVE: To assess national trends in ectopic pregnancy incidence among assisted reproductive technology users and identify risk factors associated with ectopic pregnancy.

METHODS: We identified 553,577 pregnancies reported to the National ART Surveillance System between 2001 and 2011. Of those, 9,480 were ectopic, of which 485 were heterotopic. As a result of small numbers, ectopic and heterotopic pregnancies were combined for analysis. We assessed temporal trends in annual ectopic pregnancy rates using Poisson regression. We used log-binomial regression models with generalized estimating equations for correlated outcomes within clinics to calculate unadjusted and adjusted risk ratios for the association between ectopic pregnancy and selected patient characteristics and treatment factors.

RESULTS: The rate of ectopic pregnancy declined from 2.0% (n=735, 95% confidence interval [CI] 1.9-2.2) in 2001 to 1.6% (n=968, 95% CI 1.5-1.7) in 2011 (P for trend <.001). The ectopic pregnancy rate ranged from 2.0% (n=7,469, 95% CI 1.9-2.0) for fresh, nondonor cycles to 1.0% (n=641, 95% CI 0.9-1.1) for fresh, donor cycles. Among fresh, nondonor cycles, the rate of ectopic pregnancy was 1.6% (95% CI 1.4-1.7) when one embryo was transferred compared with 1.7% (95% CI 1.7-1.8), 2.2% (95% CI 2.1-2.3), and 2.5% (95% CI 2.4-2.6) when two, three, or four or more embryos were transferred, respectively (adjusted risk ratios 1.11, 95% CI 0.94-0.30; 1.33, 95% CI 1.12-1.56; and 1.49, 95% CI 1.25-1.78).

CONCLUSION: Ectopic pregnancy incidence after assisted reproductive technology has decreased over time, but factors such as multiple embryo transfer increase the risk of ectopic pregnancy.

LEVEL OF EVIDENCE: II.