Received March 13, 2021
Accepted September 29, 2021

Objective Ectopic pregnancy is a well-known complication following in vitro fertilization with embryo transfer; studies have questioned, however, whether there are risk factors that could be identified before the procedure. The objective of this study was to investigate the possible risk factors involved in ectopic pregnancy following in vitro fertilization . Methods A retrospective case-control study was performed at an assisted reproduction clinic in Brazil. To select the control group, a ratio of 1:4 was applied. 499 patients submitted to in vitro fertilization with clinical pregnancy were included. Data were collected from electronic records, between 2000-2019 and divided into: Group 1, ectopic pregnancy (n=90) and Group 2, intrauterine pregnancies (n=409). Results and Conclusion: When comparing groups, this results observed were: Tubal factor infertility (35.6% vs. 21.1%, p=.005) (OR 2.0 [1.2-3.4], p=.004); Previous miscarriage history (15.1% vs. 7.1%, p<.05) (OR 2.0 [1.02–4.29], p=.044); Number of cleavage-state transfers (69.2% vs. 54.0 p=.028) (OR 1.9 [1.08-3.33], p=.025); Two or more embryos transferred (OR 2.5 [1.12–5.70], p=.025), all associated with greater ectopic pregnancy risk. Oocyte recipient patients were excluded from this analysis, but when included a difference was found when comparing groups (9.4% (10/106) vs. 3.0% (13/434), p=.007), (OR 3.3 [1.41-7.98] p = .005); this result should, however, be carefully interpreted given sample size. In high-risk patient’s single blastocyst transfer seems to be a reasonable approach to decrease ectopic pregnancy risk.