Serum histidine-rich glycoprotein during pregnancy and hormone treatment

The concentration of serum histidine-rich glycoprotein (HRG) was determined by radial immunodiffusion during weeks 27-42 of pregnancy in 110 pregnant women. HRG was also measured in serum from 11 lactating women 6 weeks post partum, from 11 women taking oral contraceptives, and from four women having progestin-releasing subcutaneous capsules used for contraception. The concentration of serum HRG decreased during the last trimester of pregnancy reaching a nadir at the 36-37th week (HRG 49 +/- 14 g/l, mean +/- SD). Thereafter serum HRG increased slightly towards term. In pregnancies complicated by hypertension the concentration of HRG was lower than in normal pregnancies at 32 weeks of pregnancy, but in other pathological pregnancies the values fell within the normal range. By 6 weeks postpartum normal non-pregnant HRG levels had been reached (107 +/- 13 g/l). The concentration of serum HRG was significantly lower in oral contraceptive users (74 +/- 22 g/l) than in controls (109 +/- 25 g/l, P less than 0.005). Low dose progestin treatment had no effect on serum HRG. The results show that serum HRG decreases during pregnancy and with oral contraceptive treatment and suggest that oestrogens are responsible for this increase.