At what point in pregnancy is the risk of spontaneous abortion highest?

The risk of spontaneous abortion, also known as miscarriage, is highest during the first trimester of pregnancy. This time frame encompasses the first 12 weeks, a critical period for fetal development when the pregnancy is most vulnerable. Factors contributing to this increased risk include chromosomal abnormalities in the fetus, hormonal issues, and anatomical problems within the uterus. As the pregnancy advances into the second and third trimesters, the risk of miscarriage significantly decreases as the embryo develops into a fetus, and the body's structures begin to stabilize to support the pregnancy. Therefore, selecting the first trimester as the time of highest risk aligns with established medical understanding of pregnancy and fetal development.