Miscarriage

Causes of Miscarriage

Miscarriage is the most common cause of pregnancy loss. Although miscarriage occurs in approximately 20 percent of pregnancies, many miscarriages occur before pregnancy is detected and are therefore not realized as a miscarriage. Furthermore, while most miscarriages occur at home, data on miscarriage rates are kept only for those occurring in hospitals. Most miscarriages occur before the 12th week of pregnancy; late miscarriage is recognized to be between 17 and 19 weeks' gestation inclusive. Male fetuses are more often miscarried than female. About one-third of miscarriages have no identified cause. Some early miscarriages are the result of ectopic pregnancies, where the fertilized egg implants outside of the uterus.

Other causes of miscarriage include chromosomal and genetic anomalies or other disorders that make the fetus incompatible with life, the woman's structural or hormonal makeup, other disorders or diseases preventing sustained pregnancy, and Rh [Page 778]incompatibility between the woman and fetus. As well, miscarriage is not uncommon with pregnancies accomplished through assisted reproductive technologies. Miscarriage has also been linked to maternal and paternal age at time of conception, exposure to diethylstilbestrol (DES) and toxins, smoking while pregnant, pregnancy with multiples, serious accident or violence, chronic malnutrition, and infection. Amniocentesis, a common test to detect chromosomal anomalies, usually done in the second trimester, is said to present a one in 200 risk of miscarriage. Since social determinants of health can compromise women's health generally, they can also increase risk of miscarriage. A pregnant woman cannot will a miscarriage, nor can she will its prevention.

In the case of repeat miscarriages there are tests available to determine causes and potential remedies. Diagnostic procedures, rarely done after a first miscarriage, include blood work to examine hormones, infection, antibodies, and diseases; genetic testing; ultrasound and X-rays to determine structural problems; minor surgery to visualize reproductive organs; and uterine biopsy. Although miscarriage is more likely in women who have miscarried previously, most women who miscarry will eventually have a pregnancy that continues long enough to sustain a viable baby.

Symptoms of Impending Miscarriage

Although light bleeding is not uncommon during the first three months of pregnancy, especially seven to 12 days after implantation, it can also signal a threatening miscarriage. Spotting, vaginal discharge, and cramping are considered early signs of miscarriage. Lack of fetal heart sounds indicates fetal death. Miscarriage involves vaginal bleeding, which may be heavy or light and may or may not contain clots. Because the cervix dilates and the uterus contracts, miscarriage may include cramping. When both bleeding and cramping occur, a miscarriage is more likely than as with only one symptom. Bed rest is generally recommended for threatened miscarriage. In the case of incomplete expulsion of the fetus or placenta, a dilation and curettage (D&C), which is a scraping of the uterus, will likely be needed to prevent infection. If a miscarriage occurs after 14 weeks, breastmilk production will likely begin.

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