RESUMEN
OBJECTIVE: To investigate the mononuclear cell apoptosis rate during pregnancy. MATERIALS AND METHODS: Apoptosis was quantitated by EtBr staining in whole peripheral blood samples of 135 women in different gestational weeks and 85 nonpregnant women used as controls. Apoptosis was also qualitated by TUNEL assay. RESULTS: The apoptosis rate increased during pregnancy according to gestational age. In chromosomally abnormal fetuses apoptosis was 2.5-fold higher than that found in pregnancies with normal embryos matched for gestational age. FISH in TUNEL-positive cells using X, Y and 21 chromosome probes verified the fetal origin of part of the apoptotic population. CONCLUSION: Apoptosis is stimulated in maternal peripheral blood during pregnancy, possibly accounting partly for the presence of free fetal DNA in maternal serum. The increased apoptosis rate in pregnancies with chromosomally abnormal fetuses may have additional clinical importance.