Miscarriage is the spontaneous pregnancy loss that occurs before 20 weeks of gestation. Physicians refer to this as spontaneous abortion.

According to the American Society for Reproductive Medicine (ASRM), about 25 percent of known pregnancies end in miscarriage. However, the rate is believed to be higher because many miscarriages occur very early in pregnancy, before a woman may know that she is pregnant.

The causes of miscarriage are not completely understood, but researchers believe that most miscarriages that occur in the first trimester (first 12 weeks of pregnancy) are caused by randomly occurring chromosomal abnormalities in the fetus that prevent it from developing normally. Medical conditions in the mother (e.g., uncontrolled diabetes) can also lead to miscarriage. Several autoimmune conditions as well as structural problems within the uterus may affect implantation and result in first trimester miscarriages. In addition, various risk factors, such as maternal smoking or drug abuse, can increase the likelihood of miscarriage.

Signs and symptoms of a miscarriage may include bleeding, pelvic pain or cramping in the abdomen or lower back and fluid or tissue being expelled from the vagina. Even though vaginal bleeding is usually a symptom that precedes nearly all pregnancy losses, it is not always indicative of a miscarriage. Many pregnant women experience spotting or bleeding at some point during their pregnancies.

Most women who have an early miscarriage do not require medical treatment. The uterus empties itself as it would during a heavy menstrual period. However, if an ultrasound examination shows that there is pregnancy tissue remaining in the uterus, a physician may recommend a dilation and curettage procedure or medication to induce the uterus to expel the tissue. All pregnancy tissue must be expelled and/or removed from the uterus to prevent infection. In cases of recurrent miscarriage, further testing and treatment is performed to determine the possible cause and prevent recurrence.

If a miscarriage is about to occur, it is not likely the fault of the mother and often cannot be prevented. However, a woman may decrease her chances of having a miscarriage by taking good care of herself. This includes eating a well-balanced diet, taking folic acid supplements and refraining from drinking alcoholic beverages or smoking. It is also important for pregnant women to receive good prenatal care by an obstetrician (OB) or other qualified healthcare professional. 

It is common and normal for a woman to experience sadness after losing a wanted pregnancy. Many couples benefit from support groups or psychological counseling to help deal with the emotional impact of miscarriage.

Although it is possible to become pregnant right after a miscarriage, most physicians recommend waiting at least three months before trying to conceive. Usually, most women who experience a miscarriage go on to have full-term pregnancies and healthy deliveries.