To investigate the effects of three different luteal phase support protocols on pregnancy outcomes in hormone replacement therapy frozen-thawed embryo transfer(HRT-FET).

The clinical data of 3288 HRT-FET cycles in Reproductive Center of the Third Affiliated Hospital of Zhengzhou University from January 2016 to February 2019 were retrospective cohort study analyzed. The cycles were divided into three groups according to luteal phase support protocols. The patients received a combination of progesterone soft capsule and dydrogesterone in group A (478 cycles), the patients received a combination of progesterone vaginal sustained-release gel and dydrogesterone in group B (1293 cycles), the patients received a combination of progesterone injection and dydrogesterone in group C (887 cycles). Pregnancy outcomes and neonatal outcomes in group A, group B and group C were compared.

The clinical pregnancy rate, the 12-week pregnancy rate and the live birth rate had no significant difference among the three groups (P>0.05). The rates of premature delivery and twin delivery [19.90% (78/392), 30.61% (120/392)] in group C were higher than those in group B [13.61% (109/801),P=0.011; 20.47% (164/801), P<0.001]. The birth weight [(3 178.60±635.38) g] in group B was significantly higher than that in group C [(3 033.01±682.54) g,P<0.001] . There was no significant difference in the incidence of birth defects among the three groups (P>0.05). Logistic regression analysis showed that three different luteal phase support regimens were not associated with 12-week pregnancy rate.

In HRT-FET cycle, progesterone soft capsule or progesterone vaginal sustained-release gel combined with dydrogesterone can achieve the same pregnancy outcome as progesterone injection combined with dydrogesterone, but a large-scale prospective study is needed.

Luteal phase support; Frozen-thawed embryo transfer; Hormone replacement therapy; Pregnancy outcome