Threatened miscarriage refers to the situation where abdominal pain and bleeding occur during pregnancy due to instability of the gestational sac or fetus. Most threatened miscarriages occur in the early stages of pregnancy, hence, the likelihood of experiencing threatened miscarriages during the mid or late stages of pregnancy is relatively low. Most threatened miscarriages stabilize after the first three months of pregnancy, which is approximately 12 weeks. By this time, the fetus has moved from the pelvic cavity into the abdominal cavity, and the placenta has formed. With the support of the placenta, the fetus can grow more stably. In early pregnancy, the instability of the gestational sac makes it susceptible to external influences, which can easily lead to threatened or even spontaneous miscarriage.