The impact of blastocyst level on singleton birthweight in fresh IVF-ET cycles in ART: a retrospective study

Abstract Background: The positive correlation between embryo quality and pregnancy outcomes has been well confirmed in many studies, but few studies have investigated the impact of embryo quality on neonatal weight, especially among neonates from freshly transplanted blastocysts.So the objective of the article was to compare the birth weights of infants from different blastocyst grades in fresh transplantation cycles and to explore related factors affecting birth weight. Methods: A retrospectively cohort study was performed to compare the birth weight of different blastocyst levels in fresh transplantation cycle and explore the related factors affecting the birth weight. The 1301 fresh cycles of single blastocyst transplantation and single live birth profile were retrospectively analyzed,four groups were divided according to the grade of transplanted blastocyst. There were 170 cycles in group A with AA blastocyst level, 312 cycles in group B with AB/BA blastocyst level, 559 cycles in group C with BB/CA/AC blastocyst level and 260 cycles in group D with BC/CB blastocyst level. Comparison among four groups of patients by birth weight and general conditions, fertilization rate, embryo rate, cleavage rate and D5、D6 blastocyst formation rate and other laboratory indicators were made. And then compare the birth weight of different groups which were divided by the degree of blastocyst expansion, and the classification of intracellular mass(ICM) and extracellular trophoblastic(TE). Results: The study shows that birth weight of group A was significantly higher than that of the other three groups (P < 0.05). And the high quality embryo rate and blastocyst rate of group A were significantly higher than those of the other three groups (P < 0.05). What’s more, the clinical pregnancy rate, implantation rate and live birth rate of high grade blastocyst were higher, but there was no significant difference in abortion rate. The birth weight of blastocyst of grade 3 and below was significantly lower than that of those with grade 3 and above (P < 0.05).The birth weight of grade A intracellular mass was significantly higher than that of B intracellular mass of blastocyst(P < 0.05). Babies born with grade B ectotrophoblast cells were significantly heavier than those born with grade C ectotrophoblast cells(P < 0.05). Conclusion: The authors conclude that high grade blastocyst transplantation can achieve better pregnancy outcome. Different blastocyst levels affect birth weight, and low grade blastocyst transplantation is associated with a single birth weight loss.