Comparison of Serum Pituitary Thyrotropin and Chorionic Gonadotropin Concentrations Throughout Pregnancy

Abstract

Concentrations of human pituitary thyrotropin (hTSH) and human chorionic gonadotropin (hCG) were measured by specific radioimmunoassays in serum samples obtained from 243 pregnant women. The hTSH levels demonstrated suppression during the second through the fourth months, followed by a linear rise to non-pregnant control levels throughout the remainder of gestation. At the time that the hCG levels were highest, the hTSH levels were at their lowest concentration. However, a reciprocal relationship between the hCG and hTSH concentrations in individual samples was not found.