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.