Fetal hemoglobin in women with normal and with hydatidiform molar pregnancy

The quantity and the rate of synthesis of fetal hemoglobin (HbF); the level of HbF-containing erythrocytes (F cells); and the levels of progesterone, human chorionic gonadotropin (HCG), and human chorionic somatomammotropin (HCS) in serial blood samples from women at different stages of pregnancy were determined. An increase was observed in the synthesis and the quantity of maternal HbF, reaching a peak at about 9-12 weeks gestation. A major peak in F-cell level was also detected at about 9-12 weeks, with two minor peaks appearing at about 16-20 and 22-24 weeks. Levels of HCG, HCS, and progesterone also varied during pregnancy. Timing of the rise and fall of HCG levels corresponded to that of maternal HbF levels, whereas levels of HCS and progesterone did not reach their peak until later stages of gestation when HbF level had returned to normal. Similar analysis conducted on patients with hydatidiform molar pregnancy revealed that the majority (greater than 95%) of these patients showed significant increases in HbF synthesis at the time of molar evacuation, but decreased to normal levels in approximately 30 days post-evacuation. A similar profile in the levels of HCG, but not progesterone and HCS, was observed. A positive correlation between levels of HCG and HbF can be established (correlation coefficient = 0.94). These data are in agreement with the hypothesis that HCG may act as a stimulus for the enhanced HbF synthesis in adults.