hCG is
human chorionic gonadotropin. This
glycoprotein hormone is produced when the
fertilized egg implants into the uterine lining (the
placenta) during
pregnancy. Home pregnancy tests are designed to detect this hormone. The home pregnancy tests that detect the lowest number of
mIU per
mililiter give the earliest results.
hCG is composed of two subunits. The alpha subunit is common to all
glycoprotein hormones in a given species. while the beta subunit is hormone specific.