Elevated erythropoietin levels in cord blood of newborns with Down's syndrome.

Plasma erythropoietin (Ep) was determined in umbilical cord blood in 18 infants with Down's syndrome. The 16 infants with Down's syndrome who were delivered after labor had significantly elevated plasma Ep levels compared to 36 control infants born after labor (p < 0.001). Six of the ten infants with Down's syndrome who had their packed cell volume (PCV) measured in the first 24 h of life were polycythemic based on a PCV of > or = 0.65. The presence of congenital heart disease in 9 of the 18 infants with Down's syndrome was not associated with a higher plasma Ep or PCV levels. Plasma Ep was correlated with neonatal PCV in the combined group of control and Down's syndrome infants (p = 0.003). Increased plasma Ep levels observed in infants with Down's syndrome suggested chronic fetal hypoxemia as a likely explanation for the high incidence of neonatal polycythemia observed in this group.