Abstract
Serum albumin (Alb) and IgG globulin levels in the developing fetus increase with maturity because of an increasing placental passage from the maternal circulation to the fetus. In contrast, levels of alpha-1-fetoprotein (AFP) decrease with maturity from a maximum serum level at 20 weeks of gestation (mean level > 140.0 mg%) to trace levels (mean 5 mg%) at 40 weeks gestation. These observations permit an estimation of gestational age by measuring levels of cord blood IgG, Alb, and AFP, and when paired maternal IgG and Alb levels are available, by calculating fetal/maternal IgG and Alb ratios. Cord sera (and the matfhed maternal sera) from 55 infants (23 preterm, 32 term) on whom gestational age had been estimated by maternal history and physical examination (Dubowitz criteria, J. Ped. 77:1, 1970) were studied. Gestational age was correlated (p < .001) directly with cord levels of IgG (r = 0.81) and Alb (r = 0.73) and AFP (r –0.76). Using a fetal/maternal IgG and Alb ratio did not result in an improved correlation. Although AFP was detected in all cord sera, AFP was not detected in the maternal circulation, nor in 14 of 15 amniotic fluid samples. Cord IgG and albumin levels best reflect gestational duration while cord AFP levels reflect fetal maturity.
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Hyvarinen, M., Zeltzer, P., Stiehm, E. et al. Evaluation of human gestational age by albumin, IgG globulin, and alpha-I-fetoprotein measurements. Pediatr Res 5, 416 (1971). https://doi.org/10.1203/00006450-197108000-00189
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DOI: https://doi.org/10.1203/00006450-197108000-00189