HCG (human chorionic gonadotropin) is a well-known indicator for early pregnancy monitoring, how much do you know about it and what is the pattern of change of HCG, and is higher HCG better? 1. What is HCG? HCG (human chorionic gonadotropin) is a glycoprotein hormone secreted by the trophoblast cells of the placenta. The main function of HCG is to stimulate the conversion of the corpus luteum from menstrual corpus luteum to gestational corpus luteum, while promoting the continuous secretion of estrogen and progesterone, maintaining the morphology of the endometrium, promoting the formation of the uterine meconium, and allowing the placenta to grow and mature, which is essential for maintaining pregnancy. 2. Are your HCG values normal? After the fertilized egg moves to the uterine cavity and lays in the uterus, an embryo is formed. During the development and growth into a fetus, the placental syncytial trophoblast cells produce large amounts of HCG. Generally, on the sixth day after fertilization, the trophoblast layer of the fertilized egg is formed and begins to secrete trace amounts of HCG. HCG secretion increases rapidly in early pregnancy, doubling in about 2 days. Serum HCG concentration reaches a peak at 8-10 weeks of gestation, and then decreases rapidly after about 10 days, and in the middle and late stages of pregnancy, serum concentration is only 10% of the peak and continues until delivery. If no placenta remains after delivery, it will disappear within 2 weeks after delivery. The normal reference range for HCG fluctuates widely and varies from person to person, so don’t compare it with your sisters and then worry about it blindly. In practice, the time of multiplication (the time it takes for the level to double) or the percentage of increase in two days should be further understood after the approximate range of HCG level is determined. This is why your doctor will ask you to review your blood results every other day. During the 8th-10th weeks of pregnancy, the HCG level increases more rapidly, about 1-fold every two days. 3. The best time to measure HCG It is recommended to start measuring HCG 8 days after intercourse, generally, the earliest 7 days after intercourse and the latest 3 weeks to determine if you are pregnant. Urine HCG: the accuracy rate is about 85%. In addition to intact HCG, there are many free beta-HCG and its degraded fragments. Also the concentration of HCG in the urine is related to the degree of concentration of the urine, the more concentrated, the higher the concentration of HCG, as in morning urine. It is mostly a qualitative test, and the results are judged by the naked eye and are highly influenced by personal factors. Blood HCG: Accuracy rate is up to 99%, mostly quantitative test with specific values. It can be differentiated by continuous monitoring from slight elevation of HCG during menstruation, non-specific elevation due to pituitary and other lesions, ectopic pregnancy and early miscarriage. Qualitative urine HCG cannot do any of these. Therefore blood HCG is more accurate. It is recommended that after measuring urine HCG (e.g. using early pregnancy test strips), blood HCG should be done at the hospital if possible to make a definite diagnosis.