Relationship between alpha-fetoprotein and fetal erythropoiesis.

Objective: To evaluate the relationship of fetal erythropoiesis to both maternal and fetal serum alpha-fetoprotein (AFP) levels.

Methods: We evaluated the relationships between maternal serum AFP levels and fetal hemoglobin, hematocrit, red blood cell count, mean corpuscular volume, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration in 63 fetuses, 19 of them by prenatal cordocentesis and 44 at elective cesarean section before labor. We also evaluated the relationships between fetal AFP and fetal hemoglobin, hematocrit, red blood cell count, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, erythroblasts, erythropoietin, serum iron, transferrin, ferritin, bilirubin, total proteins and albumin in 51 umbilical cords immediately after singleton childbirth, in healthy, pregnant women at term. Statistical analysis was performed by linear regression.

Results: After adjustment according to gestational age, significant correlations were found between maternal AFP and fetal hemoglobin (r = -.30, P = .017) and hematocrit (r = -.25, P = .044). We also found a significant negative correlation between fetal serum alpha-fetoprotein and fetal red blood cells (r = -.55, P = .000026), hemoglobin (r = -.40, P = .0035), hematocrit (r = -.46, P = .00052), erythropoietin (r = -.40, P = .005) and transferrin (r = -.33, P = .016). Erythropoietin also positively correlated with fetal red blood cells (r = .47, P = .001), hemoglobin (r = .45, P = .001), hematocrit (r = .47, P = .001) and erythroblasts (r = .42, P = .003).

Conclusions: Since a significant negative correlation was demonstrated between fetal red blood cell count, hemoglobin, hematocrit, erythropoietin and AFP, it is reasonable to speculate that AFP could play a role in fetal erythropoiesis.