A miscarriage occurs when a woman loses her baby before reaching the 20th week of gestation. This occurs in 15 to 20% of pregnancies and the risk increases with age. Most miscarriages, also known as spontaneous abortions, occur during the first trimester. If a viable fetus is detected (an ultrasound detects a heartbeat) in the first 12 weeks of pregnancy, the risk of miscarriage is less than 5%. If vaginal bleeding occurs after the detection of a viable fetus, the risk of miscarriage increases to about 20%.
The risk of having recurrent miscarriages varies enormously from one woman to another. Women who have completed at least one normal pregnancy have a better chance of having healthy pregnancies in the future, even if they miscarry. A complete evaluation is usually performed only after two or three consecutive miscarriages. In half of the couples whose wives are repeatedly miscarried, it will be possible to find the cause of these miscarriages and to treat it. A chromosomal abnormality of the embryo is the cause of most miscarriages. The cause is almost never associated with the health of the mother, although the risk of miscarriage increases in women over 35 years of age. From the age of 40, the risk of miscarriage is 35 to 40% and from age 45, the risk is more than 50%.
Repeated miscarriages could be caused by some of the following factors:
- Abnormal form of the uterus
- Uterine fibroids
- Genetic abnormalities
- Hormonal disorders
- Immunological factors