Both hCG and progesterone values are used to assess pregnancy, and progesterone values are also used as a test for the presence or absence of ovulation. hCG, human chorionic gonadotropin, is a hormone secreted by gestational trophoblast cells after the fertilized egg is laid. In early pregnancy hCG usually rises 1.7-2 days, peaks at 8-10 weeks of gestation, and then declines rapidly. hCG is only 10% of the peak in mid to late pregnancy. hCG doubling is not satisfactory or remains at low levels, and ectopic pregnancy should be suspected. Progesterone, also called luteinizing hormone, is a progestin that is secreted by the ovaries before ovulation, but in very small amounts, and in large amounts by the corpus luteum in the ovaries after ovulation. Progesterone will reach its peak 7 days after ovulation. If the egg and sperm do not unite for fertilization after ovulation, the corpus luteum will shrink and the progesterone in the body will drop rapidly. As a result, the endometrium sheds and vaginal bleeding, or menstruation, occurs. If a fertilized egg is formed, then the corpus luteum continues to secrete progesterone, which reduces uterine contractions and facilitates the fertilized egg’s implantation and the smooth development of the embryo. Progesterone can be used to determine whether a woman is ovulating or not, and for women who are infertile this indicator can be tested, usually before the onset of menstruation. A successful pregnancy cannot be achieved without the support of progesterone, and a particularly low progesterone level in early pregnancy indicates a poor outcome of this pregnancy. Therefore, both hCG and progesterone are used as indicators to detect pregnancy, the main difference being that hCG is present in the body only after pregnancy, while progesterone is always present and will be significantly higher after pregnancy compared to non-pregnancy.