Practice Essentials
Early pregnancy loss is defined as the termination of pregnancy before 20 weeks’ gestation or with a fetal weight of below 500 g. According to the definition set forth by the American Society for Reproductive Medicine, recurrent pregnancy loss is a disease distinct from infertility and is defined by the spontaneous loss of two or more pregnancies.
Genetic causes
Most spontaneous miscarriages are caused by an abnormal (aneuploid) karyotype of the embryo. At least 50% of all first-trimester spontaneous abortions (SABs) are cytogenetically abnormal
Miscarriages are common, occurring in 15-20% of all pregnancies, usually in the first trimester (up to 13 weeks). One or even two miscarriages are not, by themselves, indicative of future infertility. Nonetheless, they may leave patients concerned and questioning their ability to have a live birth.
More than half of the time, couples will go on to have healthy children, unassisted, after losing two pregnancies. However, you may want to look more closely at possible causes if you have not had a live birth and have had two or more miscarriages.
Types of miscarriage
There are many causes of miscarriage, but they are usually divided into two groups: early and late.
Recurrent early miscarriages (within the first trimester) are most commonly due to genetic or chromosomal problems of the embryo, with 50-80% of spontaneous losses having abnormal chromosomal number. Structural problems of the uterus can also play a role in early miscarriage.
Recurrent late miscarriage can be the result of uterine abnormalities, autoimmune problems, an incompetent cervix or premature labor.
