Effects of frozen thawed embryos versus frozen thawed blastocysts on transfer period and delivery outcomes / 中国组织工程研究

ABSTRACT

BACKGROUND:Since the first frozen embryo transplantation succeeded in 1983, embryo cryotechnique has been an important component in human assisted reproductive techniques. It is controversial which embryos and blastocysts after cryopreservation is selected. OBJECTIVE:To compare the birth outcomes and neonatal status of frozen thawed embryos and blastocysts. METHODS:In frozen thawed embryo group (n=1 273) and frozen thawed blastocyst group (n=471), we compared pregnancy rate, abortion rate, ectopic pregnancy rate, premature delivery rate, average premature gestational weeks, term yield, average ful-term gestational age, newborn sex, birth weight, birth defects and so on. RESULTS AND CONCLUSION:There were frozen thawed blastocyst thaw cycles in 478 cases, 471 cases of transplantation period (including 7 cases without blastocyst transfer were canceled), 236 cases of pregnancy, 201 cases of delivery. Delivery number was 251, including 140 boys and 111 girls. The third day embryo thawing cycle of freezing and thawing appeared in 1 280 cases, 1 273 cases of transplantation period (including 7 cases of no embryo transplantation were canceled), 415 cases of pregnancy, 343 cases of delivery. The delivery number was 431, including 225 boys and 206 girls. Rate of pregnancy was significantly higher in frozen thawed blastocysts compared with frozen thawed embryos. No significant differences were detected in rate of miscarriage, ectopic pregnancy rate, premature delivery rate, average premature gestational weeks, term yield, average ful-termgestational age, newborn sex, and birth weight between frozen thawed embryos and blastocysts. There was no increase in birth defects between frozen thawed embryos and blastocysts. Results suggested that no significant difference was detected in birth outcomes and neonatal status of frozen thawed embryos and blastocysts. Nevertheless, pregnancy outcome is better in frozen thawed blastocysts than frozen thawed embryos.