In vitro fertilisation (IVF) is one of the major risk factors for an ectopic pregnancy (EP). Rates of EP in women undergoing IVF range from 2–5%, which is higher than the rate among spontaneous pregnancies at 1–2%.1 In fact, the ﬁrst IVF pregnancy reported was also an EP.2 The main risk factors for EP following the use of assisted reproductive technology (ART) are tubal factor infertility, uterine contractions or dysfunction of uterine musculature due to supra physiological hormone levels because of ovarian stimulation, high culture medium volume, or a faulty embryo transfer. Recent research has suggested that frozen-thawed embryo transfer (FET) is associated with a greatly reduced incidence of EP compared with fresh transfers. The current study was undertaken to evaluate the incidence of EP in fresh and frozen embryo transfer at a tertiary fertility centre in India.
A prospective cohort study was carried out through 1st January 2016 to 31st December 2018 at Akanksha IVF Centre, New Delhi. A total of 671 fresh cycles and 767 FET cycles were included for analysis. A maximum of two embryos were transferred under ultrasound guidance by the single operator. For the 671 fresh IVF-ET cycles, 286 patients had clinical pregnancies and 20 patients had EP, and out of 767 FET cycles, 375 patients had clinical pregnancy and 10 patients had EP. The clinical pregnancy rate in fresh IVF-ET cycles was 42.62% and in FET cycles was 48.89%, which was statistically significant (p=0.02). The incidence of an EP per embryo transfer was also significantly higher for the fresh group (2.23% [20 of 671]) versus the FET group (1.04% [10 of 767] [p=0.042]). The majority of patients with EP had tubal factor as a cause of infertility. There was a statistically significant difference in EP rate in fresh versus FET cycles when Day 3 embryos were transferred (13 versus 5; p=0.05) but the difference was not significant when Day 5 embryos were transferred in the fresh and FET groups (7 versus 5; p=0.6).
This study suggests that FET is associated with significantly lower rates of EP compared with fresh cycles. The findings are consistent with database from The Society for Assisted Reproductive Technology (SART) registry published by Londra et al.3 and Huang et al.4 The authors also found that there was no difference in EP rates in fresh and frozen cycles when blastocysts were transferred. The main limitation of the study is that it was a cohort study at a single centre with a small sample size. Further multicentric trials are needed to validate the findings.
In conclusion, FET is associated with significantly lower rates of EP compared with fresh cycles. These findings suggest that increased chance of EP is due to disturbed hormonal milieu of ovarian stimulation. Freeze all strategy followed by FET would decrease the incidence of EP in ART. In cases of fresh transfers, performing a Day 5 transfer would decrease the chances compared to Day 3 transfer.