A miscarriage is defined as the loss of a fetus before 20 weeks of pregnancy. Miscarriages typically occur in the first trimester of a pregnancy (prior to week 13). Miscarriages can happen for a variety of different reasons, ranging from genetic and chromosomal issues within the embryo to underlying conditions.

What is a miscarriage?

A miscarriage (also known as “spontaneous abortion”) is defined as a spontaneous loss of pregnancy before the 20th gestational week. Miscarriages occur most frequently in the first trimester of pregnancy, typically up until the 13th week. In fact, 8 out of 10 miscarriages happen within the first three months. 

Patients can experience miscarriages for a variety of reasons, including genetic disorders, chromosomal issues, underlying medical conditions, or the poor development of the embryo. Terms to know:

• Threatened miscarriage: signs of the potential for pregnancy loss.
• Complete miscarriage: when all fetal tissue is passed out of the uterus.
• Incomplete miscarriage:, fetal tissue is not entirely passed out of the uterus.
• Inevitable miscarriage: when a miscarriage is already in process and cannot be prevented.
• Missed miscarriage: a miscarriage that occurs without symptoms, such as bleeding or pain.

Causes of miscarriages

Causes for miscarriages span a number of factors, but the majority are caused by abnormal chromosomes. For instance, if the fertilized egg has too many or too few chromosomes, it will likely lead to a miscarriage, as the embryo will not develop properly. These miscarriages are inevitable, due to the abnormal genetics of the fetus. Other possible causes for miscarriages include underlying medical conditions, such as uncontrolled diabetes; hormonal problems, uterus or cervix issues; or thyroid disease. Abnormalities in the uterus, specifically, can cause miscarriages even after the first trimester.

Those that have already had a miscarriage are at a higher risk of having another miscarriage should they get pregnant a second time. However, the vast majority of people who experience a miscarriage will go on to have a healthy pregnancy and birth. Two or more consecutive miscarriages is known as recurrent miscarriage or recurrent pregnancy loss, experienced by less than 5% of pregnant people.

Symptoms of miscarriages

Vaginal spotting or bleeding after a positive pregnancy test is a common symptom of miscarriage. Patients experiencing abdominal pain or cramping in the lower back should consider seeking medical attention for further evaluation. Miscarriage can also be diagnosed based on an ultrasound scan in which bleeding can be visualized or a heartbeat cannot be found.

Treatment of miscarriages

Miscarriages are a common occurrence — experienced in around 20% of pregnancies — and are typically difficult to prevent, since the primary cause is genetic. Prior to getting pregnant, it is helpful to understand miscarriages, their common causes, and possible outcomes. In addition, understanding potential risk factors that contribute toward miscarriages can help alleviate stress throughout pregnancy.