Effects of artificial shrinkage of blastocoeles before vitrification on pregnancy outcome

Objective To investigate the effects on pregnancy outcome and neonate by artificial shrinkage by microsucting the fluid of expanded blastocysts before vitrification using glass micropipette (GMP).Methods From Jan.2006 to Dec.2009, 342 vitrified-thawed blastocyst cycles from patients that performed in vitro fertilization-embryo transfer (IVF-ET) or intracyteplasmic sperm injection ( ICSI ) were enrolled in this study in Reproductive Medicine center, Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region.Three hundred and fourteen cycles of expanded blastocysts were artificially shranked by microsucting blastocoelic fluid with a micro-needle before vitrification as artificial shrinkage group, in the mean time, 28 cycles without artificial shrinkage were chosed as control group.The survival rate, implantation rate, clinical pregnancy rate and transfer canceled rate were compared between artificial shrinkage group and control group.Among pregnant women, the miscarriage rate, live birth rate, congenital birth defect rate, neonatal weight and gestational age were compared with those of fresh embryo transfers in 520 cycles.Results The blastocyst survival rate, implantation rate and clinical pregnancy rate were 95.3%(403/423), 38.0% ( 153/403), 44.6% (140/314) in artificial shrinkage group and 64.3 % (27/42),7.4% (2/27), 7.1% (2/28) in control group, respectively, which reached statistical difference (P＜0.05).The transfer canceled rate was 0 in artificial shrinkage group and 25.0% (7/28) in control group, which also reached statistical difference ( P ＜ 0.05 ).Among pregnant patients, the miscarriage rate of 18.2% (10/55), live birth rate of 80.0% (44/55), gestational age of (38.2 ± 1.3) weeks, congenital birth defect rate of 2.1% (1/47), birth weight of newborns of (2989 ±640) gram in artificial shrinkage group were not significantly different with 17.5% (91/520), 74.0% (385/520), (37.9 ±2.3) weeks,1.7% (8/479) and (2856±640) gramin fresh embryo transfer group (P＞0.05).Conclusion Artificial shrinkage by microsucting blastocoelic fluid with a micro-needle before vitrification significantly improved the vitrification effects of expanded blastocyst and no distinct increasing rate of neonates congenital anomality were observed. Key words: Embryo transfer; Blastula; Freezing; Pregnancy outcome; Infant, newborn