I don’t advocate HCG and progesterone tests in early pregnancy to guide early pregnancy preservation. In fact, checking HCG and progesterone is a trendy thing to do in China, and many doctors will tell you that your HCG and progesterone are low and you need to take some injections. I do not agree with this practice. HCG is secreted by the cells of the syncytial trophoblast. What is the syncytial trophoblast is simply the part of the fertilized egg that will form the placenta in the future after division, it is not part of the fetus. Therefore, the HCG level reflects the development of the cells in the syncytial trophectoderm, and we often see cases where the HCG is 100,000 or more, but the pregnancy is still an empty sac. The HCG is not always rising, it starts to drop around 8 weeks, so it’s not that the fetus is bad if it drops. Some people may say that monitoring the doubling of HCG can tell whether the embryo is developing well or not, but in fact, as already mentioned, HCG is not secreted by the embryo itself, so how can it reflect the good or bad fetus. By doubling, we mean that every 2-3 days, the HCG value doubles. Of course, if the HCG doubling is very poor and the peak is below 20,000, we think that such embryo may be bad indeed. But a new question arises, is it that with very poor doubling and low peak, we have a way to improve this situation, unfortunately, none of the therapeutic measures we can think of, whether it is low molecular heparin, progesterone, HCG or immunotherapy such as immunoglobulin, fat milk, LIT, etc., can improve the quality and survival of the embryos. In one of the trials, low molecular heparin treatment improved the development of trophoblast cells and increased peak HCG levels, but unfortunately, the syncytial trophoblast is not the fetus and low molecular heparin treatment did not improve fetal survival. What about the other test “progesterone”? Here I’ll borrow a quote directly from Professor Duan Tao (because I’m too tired to code myself, bad). The reason for testing progesterone is that one of the major causes of miscarriage is luteal insufficiency (a small percentage), which leads to low progesterone levels and further leads to miscarriage. If detected in time, progesterone can be supplemented to prevent miscarriage from occurring. In fact, the gold standard for the diagnosis of luteal insufficiency is two endometrial biopsies performed at mid-luteal phase, and it is almost impossible to use such a gold standard for diagnosis in clinical practice. This is why some people propose to check the progesterone level to determine luteal function, but this method is not reliable: 1, the progesterone level of normal pregnancy fluctuates greatly (in fact, the same person may have a great difference between two tests on the same day); 2, low progesterone level is more a result of embryonic dysplasia than a cause of miscarriage; 3, half of the patients diagnosed with luteal insufficiency have normal progesterone level; 4, during early pregnancy, the source of progesterone is normal. During early pregnancy, there are 2 sources of progesterone, one is secreted by the corpus luteum and the other is secreted by the trophoblast, so it is impossible to tell which cause the low level is. For these reasons, I do not advocate routine testing of HCG and progesterone, because such tests may look wonderful, but they seem very weak in terms of interpretation, prediction and intervention. Since the predictive value is limited and interventions are ineffective, sometimes such tests just add to the anxiety of the parents-to-be, so I do not routinely check them, and even if I do, it is never for the purpose of guiding the use of medication for fertility preservation. What are the circumstances in which I would check? In a pregnant woman with ovulation disorders, where the exact time of ovulation is not known and ultrasound does not reveal clinical evidence of pregnancy, I would choose to check HCG to help determine the time of conception and progesterone to help determine the likelihood of ectopic pregnancy and miscarriage.