Jwa SC, Seto S, Takamura M, et al. - Researchers conducted a registry-based retrospective cohort study with the aim to determine the risk of ectopic pregnancies (EPs) for fresh cycles according to different ovarian stimulation protocols. Among a total of 68,851 clinical pregnancies after fresh single embryo transfer between 2007 and 2015, 1,049 (1.46%) cases of EP were reported. Observations revealed significant correlation of ovarian stimulation protocols with an increased risk of EP. In particular, the highest risk of EP was evident in correlation with ovarian stimulation with clomiphene vs other stimulation protocols.