Atosiban improves implantation and pregnancy rates in patients with repeated implantation failure

Abstract

This prospective cohort study examined the effects of atosiban on uterine contraction, implantation rate (IR) and clinical pregnancy rate (CPR) in women undergoing IVF/embryo transfer. The study enrolled 71 women with repeated implantation failure (RIF; no pregnancies from an average of 4.8 previous embryo transfers with a mean of 12 top-quality embryos) undergoing IVF/embryo transfer using cryopreserved embryos. The total atosiban dose was 36.75 mg. The IR per transfer and CPR per cycle were 13.9% and 43.7%, respectively. Before atosiban, 14% of subjects had a high frequency of uterine contractions (≥ 16 in 4 min). The frequency of uterine contractions was reduced after atosiban. This reduction of uterine contractions in all cycles was significant overall (from 6.0 to 2.6/4 min; P<0.01), in cycles with ≥ 16 uterine contractions/4 min at baseline (from 18.8 to 5.1; P<0.01) and in cycles with <16 uterine contractions/4 min (from 3.9 to 2.2; P<0.01). IR and CPR improved in all subjects, irrespective of baseline uterine contraction frequency. This is the first prospective study showing that atosiban may benefit subjects with RIF undergoing IVF/embryo transfer with cryopreserved embryos. One potential mechanism is the reduction in uterine contractility, but others may also contribute. Many women undergoing IVF/embryo transfer do not achieve the outcome that they wish for. In fact, IVF/embryo transfer repeatedly fails for a subgroup of patients. There are limited options available to help these patients with repeat implantation failure (RIF) to become pregnant. This study looks at one potential new treatment option for women who experience RIF. A drug called atosiban is already being used to delay premature labour by inhibiting contractions of the uterus. In this study, atosiban was given at the time of embryo transfer to women undergoing IVF/embryo transfer. Atosiban reduced the number of uterine contractions in these patients and also increased the implantation and pregnancy rates. The pregnancy rate went from zero to 43.7%. The beneficial effects of atosiban were observed not only in patients who had a high frequency of uterine contractions at baseline but also in those who had a low frequency. These findings suggest that atosiban may have other benefits in addition to its effect on contractions of the uterus. More studies are required to find out exactly how atosiban works and to increase the knowledge of its use in patients with RIF undergoing IVF/embryo transfer.