Objective: The aim of the present study was to analyze the presence of maternal cells in human fetal tissues in the second trimester.
Study design: Tissues from 11 second-trimester fetuses terminated because of social reasons or because of malformations and/or trisomy were investigated. By cell sorting and polymerase chain reaction amplification, we studied the presence of maternal CD3+, CD19+, CD34+, and CD45+ in different fetal tissues and in placenta.
Results: In the group of fetuses with normal karyotype and normal autopsy findings, 4 of 5 fetuses were positive for maternal microchimerism. In the group in which the fetuses were diagnosed with trisomy 21 and/or malformations, we found cells of maternal origin in 3 of 6 fetuses.
Conclusion: The results from this study indicate that maternal microchimerism is a common phenomenon in the second-trimester fetuses. Maternal cells of lymphoid and myeloid lineages and hematopoietic progenitors are widely distributed in the second-trimester fetuses.