HCG will double 8-15 days after ovulation, after intercourse the fertilized egg will be implanted within 1 week, usually the HCG will double the next day after implantation, HCG doubling should be combined with progesterone to observe. If the progesterone increases together, we can consider to exclude the problem of abnormal embryonic development. It is more accurate to observe whether the HCG has doubled about 15 days after intercourse, and the HCG doubles every 48 hours. At different stages of pregnancy, the HCG index is different. In the first 8 weeks of pregnancy, the HCG increases rapidly in order to maintain the internal environment needed for pregnancy, and after 8 weeks of pregnancy, the HCG index gradually decreases until it stabilizes at about 20 weeks. During pregnancy, you should maintain a healthy lifestyle and take supplemental folic acid tablets and other nutrients according to your doctor’s advice. During pregnancy, pregnant women should take rest and avoid coitus to prevent the fetus from being harmed.