Plasma protein levels in normal human fetuses: 13 to 41 weeks' gestation.

OBJECTIVES

To establish reference ranges for the levels of alpha-fetoprotein, albumin, prealbumin (transthyretin) alpha-1-antitrypsin, transferrin, ceruloplasmin and total protein in the plasma of normal human fetuses and newborn babies.

DESIGN

Prospective study of individual normal cases to fulfil objectives.

SETTING

Pathology laboratories of the University of Edinburgh and the biochemistry laboratories of the University of Keele.

SUBJECTS

Twenty-two normal fetuses 13 to 22 weeks of gestation and 66 babies born between 24 and 41 weeks gestation.

RESULTS

Albumin is the predominant plasma protein throughout gestation. The levels of alpha-fetoprotein and prealbumin fell significantly with increasing gestation, whereas the concentrations of the other proteins studied increased. The ratios of individual proteins to total protein demonstrated similar trends.

CONCLUSIONS

This study provides developmental profiles of normal human fetal plasma proteins to serve as possible reference data for abnormal fetuses. Declining levels of prealbumin (transthyretin) were unexpected and suggest a functional role for this protein in early pregnancy.