Factors Analysis of Spontaneous Abortion after Thawed-vitrified Blastocysts Transfer

ObjectiveTo investigate the factors resulting in spontaneous abortion after transferring frozen-thawing blastocysts.MethodsA total of 108 cases transferring vitrified blastocysts were divided into two groups: abortion group (n=20) and ongoing group (n=88). Cytogenetic analysis of apoblemas was performed in 12 cases of the abortion.ResultsThe overall spontaneous abortion rate was 18.50%(20/108) and the early spontaneous rate was 16.67%(18/108). A significant difference in maternal age was observed (abortion group: 33.3 ± 4.0 years, ongoing group: 31.0 ± 3.6 years, P=0.02). No difference in other parameters was found. Cytogenetic analysis of apoblemas was obtained for 12 cases, and 2 specimens were contaminated. Seven of ten patients had abnormal karyotypes.ConclusionThe underlying cause of spontaneous abortion after transferring frozen- thawing blastocysts appears to be abnormal karyotypes. Advancing maternal age seems to increase the risk of spontaneous abortion.