Comparative study between natural cycles and programmed cycles using exogenous steroid hormones for endometrial preparation in cryopreserved-thawed blastocyst transfer / 대한산부인과학회지

ABSTRACT

OBJECTIVE: The objective of this study was to compare the outcomes of cryopreserved-thawed blastocyst transfer (CT-BT) in natural or programmed cycles using exogenous steroid hormones. METHODS: A total of 221 CT-BT cycles were included and divided into two groups according to endometrial preparation protocols. In natural cycle group (n=116), monitoring was performed by transvaginal ultrasonography to detect ovulation. In programmed cycle group (n=105), oral estradiol valerate, 6 mg/day, was started on the third day of the menstrual cycle and administered continuously, and progesterone in oil 100 mg i.m. daily injection was started on cycle day 15. CT-BTs were performed on five days after ovulation in natural cycles and five days after the initiation of progesterone administration in programmed cycles. Pregnancy rates, implantation rates, and other clinical characteristics of the two groups were compared. RESULTS: Clinical characteristics of study subjects did not differ between the two groups. Post-thaw survival rates, number of transferred blastocysts, and number of good-quality blastocysts were not different. There were no statistically significant differences in implantation rates (21.1% vs. 19.4%), clinical pregnancy rates (36.2% vs. 36.2%), and ongoing pregnancy rates (28.4% vs. 27.6%) between the two groups. CONCLUSIONS: No statistically significant differences were found in pregnancy rates and implantation rates between the two protocols. Our results suggest that both protocols are equally effective for endometrial preparation in CT-BT cycles.