Number of embryos transferred could possibly be associated with angular pregnancy in in vitro fertilization‐embryo transfer

OBJECTIVE: The probability of embryo implantation in an abnormal location is significantly higher in assisted reproductive technology (ART) than in natural pregnancies. Angular pregnancy is an eccentric intrauterine pregnancy with embryo implantation in the lateral superior angle of the uterine cavity. Cycle-level factors associated with angular pregnancy in patients conceived with ART needed to be explored. METHODS: A total of 11 336 clinical pregnancies cycles were included. Angular pregnancy rate was compared among groups according to the type of embryos transferred. Among them, 53 cases of angular pregnancy and 159 cases of normal intrauterine pregnancy were screened out using propensity score matching. Risk factors of angular pregnancy were explored. RESULTS: The angular pregnancy rate was 0.31% (14/4572) in the day 5 blastocyst transfer group, 0.58% (39/6764) in non-day 5 embryo transfer group, with 0.55% (29/5280) in day 3 embryo transfer and 0.67% (10/1484) in the day 6 blastocyst group, respectively. A multifactor regression analysis was performed and indicated that the number of embryos transferred was significantly associated with angular pregnancy (P = 0.031, OR, 2.23, 95% CI: 1.09-4.68). CONCLUSION: Multiple embryo transfer could possibly be associated with an increased incidence of angular pregnancy in patients conceived with ART.