Elevated 7B2 levels during normal human pregnancy

In a cross-sectional study the plasma concentrations of immunoreactive 7B2, a novel protein originally isolated from the pituitary gland, was measured in 60 healthy pregnant and postpartum women. The mean circulating concentration of 7B2 immunoreactive equivalents was found to be significantly increased throughout pregnancy (10 to 12 weeks, 52.2 ± 13.1 pmol/L; 20 to 22 weeks, 74.4 ± 20.1 pmol/L; 30 to 32 weeks, 56.0 ± 12.9 pmol/L; and 36 to 40 weeks, 85.7 ± 13.6 pmol/L) when compared with a group of 32 age-matched nonpregnant controls (19.7 ± 5.0 pmol/L);(p < 0.01). The highest 7B2 plasma concentrations were found shortly before delivery (36 to 40 weeks) and fell sharply after birth, returning to normal within 4 to 6 weeks. Fetal plasma from both umbilical artery and vein was found to have particularly high concentrations of 7B2-like immunoreactivity (396 ± 19 and 361 ± 24 pmol/L, respectively); and 7B2 was extractable from the placenta. Chromatographic analysis of plasma and tissue extracts showed the main peak of immunoreactivity to coincide with that originally described in the pituitary gland. Although the function of 7B2 is at present unknown, our data suggest that 7B2 immunoreactivity in fetal blood originates from the fetus and may play an important role in pregnancy.