Effect of frozen-thawed embryo transfer on metabolism of children in early childhood

Abstract Background: As a routine procedure in assisted reproductive technology (ART), it is crucial to assess the safety of frozen and thawed embryo transfer (FET). We aimed to investigate the metabolic profile of children conceived through FET between the ages of 1.5 and 4. Method: 284 children between the ages of 1.5 and 4 years old, conceived through FET or spontaneously conceived, were recruited. A total of 147 children were included in the biochemical and metabolomics analysis (118 were born following FET and 29 were conceived spontaneously). Results: Children in the FET group had higher plasma ApoE and lower fasting insulin than those in the NC group. There were 11 small molecule metabolities that differed between the FET and NC groups: short chain fatty acid and secondary bile acid were higher in the FET group, whereas medium and long chain fatty acids were lower. Conclusion: We found that the fasting insulin level and HOMA-IR index which related to glycometabolism were decreased in FET group. Increased level of ApoE and decreased level of medium and long chain fatty acids in FET group indicated the abnormal lipid metabolism of children born after FET. Meanwhile, the increase of SCFAs (short chain fatty acids) level and secondary bile acids in FET group may suggeste the active metabolism of intestinal flora of children conceived from FET.