Human chorionic gonadotropin (hCG) is a hormone produced by trophoblast tissue, which is typically found in early embryos and eventually develops into part of the placenta. Measuring hCG levels can help distinguish between normal and abnormal pregnancies and is also useful for monitoring after a pregnancy loss. In addition, hCG testing can aid in the diagnosis of certain cancers, such as choriocarcinoma and some extra-uterine malignancies. Exogenous administration of hCG as a bolus is standard practice for in vitro fertilization transfer care.