A spontaneous abortion occurs in early pregnancy when the uterus evacuates the products of conception. A complete spontaneous abortion is when the uterus expels all of the pregnancy tissue. If there is vaginal bleeding but tissue remains in the uterus and the cervical os is dilated, this is considered an incomplete abortion. A missed abortion is defined as a pregnancy loss with a closed cervical os.

Approximately 10% of clinically recognized pregnancies end in a miscarriage, and 80% of these occur within the first trimester. It is estimated that about 50% of these losses are due to fetal chromosomal abnormalities.

Vaginal bleeding and uterine cramping are the main symptoms of pregnancy loss.

Risk factors for early pregnancy loss included advanced maternal age, history of prior pregnancy loss, endocrine abnormalities (eg, diabetes, thyroid disease), short intervals between pregnancies, infections, autoimmune diseases, and uterine anomalies.

Related topic: stillbirth