Variability in Thyroid-Stimulating Hormone Suppression by Human Chronic Gonadotropin during Early Pregnancy

In early pregnancy, a woman's centile TSH level appears to determine susceptibility to the TSH being suppressed at any given hCG level, suggesting that hCG itself may be the primary analyte responsible for stimulating the thyroid gland. hCG affects lower centile TSH values disproportionately.