The first trimester of pregnancy is the most vulnerable stage for miscarriage, usually referred to as the first 3 months of pregnancy, i.e. up to 12 weeks. The risk of miscarriage is increased when the progesterone is low, the HCG level is not high or the pregnant woman is not resting well because the gestational sac is small at this time and due to the influence of the hormone level in the body. Therefore, in early pregnancy, it is recommended to pay proper attention to rest, do not engage in strenuous exercise, do not walk for a long time, and try to avoid frequent bending and squatting. In case of abdominal pain, bleeding or low progesterone, you need to keep the baby in time. However, there are some miscarriages that are difficult to avoid, which are mainly due to abnormal development of the embryo itself.