What Causes Miscarriage?
Approximately 50 to 75 percent of all miscarriages are the result of chemical pregnancies, or pregnancies that result in embryonic death before the fertilized egg even implants in the uterine lining. Most chemical pregnancies are the result of chromosomal abnormalities that result from either damaged sperm or egg cells or a problem with cell division during the blastocyst stage. Several conditions can also cause miscarriage after implantation. They include blighted ovum, where the fertilized egg implants and develops a membrane and placenta, but no fetal tissue develops, intrauterine fetal demise, where the fertilized egg implants and and fetal tissue is present, but the tissue is no longer viable, and molar pregnancy, which occurs when the egg implants and a fetus may or may not be present, but placental cysts prevent the healthy development of the fetus. An ectopic pregnancy occurs when the fertilized egg implants somewhere other than in the lining of the uterus. If miscarriage does not occur naturally during an ectopic pregnancy, medical intervention is necessary to terminate the pregnancy because of the risk to the mother's life.
There are certain lifestyle choices that can increase the odds of miscarriage. Smoking, heavy alcohol use, and drug use, especially early in pregnancy, can all increase the likelihood of miscarriage. Being either underweight or overweight can also increase a woman's chances of miscarrying.
There are a few maternal health conditions that can lead to miscarriage if they are not properly diagnosed and treated. They include diabetes, certain thyroid conditions, abnormal hormone levels, uterine or cervical abnormalities, and infection.
Some prenatal tests, including chorionic villus sampling and amniocentesis, carry a slight risk of causing miscarriage.
What Doesn't Cause Miscarriage?
Despite many myths and old wives' tales, moderate exercise, sex during pregnancy, working outside the home, suffering morning sickness, experiencing a frightening moment, and using the birth control pill before you realized you were pregnant do not increase the chances of miscarriage.