Miscarriage is a spontaneous termination of pregnancy at any time from conception to full term (37 weeks).
Loss of pregnancy before 22 weeks is a spontaneous miscarriage. If the pregnancy is terminated after more than 22 weeks, it is already considered to be a preterm birth. Losing a pregnancy three or more times is called recurrent miscarriage. If the dead fetus or embryo is asymptomatic for some time in the uterine cavity, such a pregnancy is called frozen. The category of missed pregnancies includes anembryony, in which an empty fetal egg is determined in the uterine cavity.
The frequency of miscarriage is from 15 to 20% of all diagnosed pregnancies. The frequency of interruption in the first trimester reaches 50%, in the second trimester it is about 20%, and in the third trimester - up to 30%.