Introduction:
Women with PCOS have been reported with low pregnancy rate and high OHSS risk in IVF programs due to the decreased endometrial receptivity and high ovarian reserve. The GnRH antagonist (GnRH-ant) protocol has been widely accepted as a prominent intervention to reduce the risk of OHSS, and the depot GnRH agonist (dGnRH-a) protocol are believed to improve endometrial receptivity and increase the pregnancy rate of fresh embryo transfer.

Material and methods:
This study was a retrospective cohort study that included 2164 women with PCOS undergoing assisted reproductive technology (ART) treatment from January 2014 to April 2019. The two groups were matched by propensity scores with a ratio of 4:1 accounting for potential confounding factors.

Results:
The live birth per treatment cycle was higher in the dGnRH-a group than in the GnRH-ant group (58.22% vs. 41.78%, P=0.0004), the same with live birth per fresh transfer (64.42% vs. 44.64%, P=0.0045). There were no significant differences in the incidence of moderate-to-severe OHSS (4.28% vs. 2.05%, P=0.333) and the cost of COH (RMB: 7736.9 vs. 8046.54, P=0.113) between the two groups.

Conclusions:
Our results indicated that the dGnRH-a protocol has a higher live birth rate than GnRH-ant protocol, and the difference is mainly due to fresh embryo transfer. For safety and economic cost, the incidence of moderate-to-severe OHSS and cost of COH is similar in two groups. Nevertheless, the incidence of moderate-to-severe OHSS in the dGnRH-a group is numerically higher than GnRH-ant protocol with no statistical difference. A subsequent prospective randomized controlled study is needed to confirm these results.