Generally speaking, it is easier to miscarry before 12 weeks of pregnancy. Because the placenta is not stable at this time, it cannot give strong protection to the embryo, so it is very easy to cause miscarriage. When a woman reaches the 12th week of pregnancy, that is, from the third trimester, the placenta is basically fully developed, the fetus is about 75mm, and all its organs are beginning to differentiate and work. At this time, the presence of the fetal sac can be clearly seen through the ultrasound, and there will be a fetal bud and a fetal heartbeat, so it is most likely to miscarry before the 12th week and to stabilize after that. However, at this time, it is also necessary to pay attention to not doing strenuous exercise, to take rest, and to strengthen the nutrition of the pregnant mother to supply the growth and needs of the fetus. If there is any abnormality in the body, she should go to the hospital for consultation and treatment in time. Therefore, it is easier to miscarry before 12 weeks of pregnancy.