Spontaneous abortion is the medical term for a miscarriage. Before 20 weeks a pregnancy loss is referred to as a miscarriage; after 20 weeks it is technically a stillbirth.
How Common is Miscarriage?
For a woman of childbearing years, the chance of having a miscarriage ranges from 10% to 25% depending on her age and general health. Women under 35 in generally good health have about a 15% chance of miscarriage [American Pregnancy Association].
Here are some statistics from the American Pregnancy Association:
- 670,000 American women miscarry a pregnancy each year
- Most miscarriages occur during the first 12 weeks of gestation
- Between 15% and 20% of all clinically recognized pregnancies end in miscarriage
Does a Woman Always Know She's Had a Miscarried Pregnancy?
Chemical pregnancies, which are pregnancies lost just after implantation, are thought to account for 50% to 75% of all miscarriages. This means that a majority of miscarriages happen before a woman even knows she is pregnant, and what she thinks is her normal period is actually a miscarried pregnancy. A late period is also a sign of a possible early miscarriage.
Implantation and embryo development are complicated processes, and anything that doesn't go perfectly usually results in a miscarried pregnancy. A miscarriage is usually the body's way of dealing with a pregnancy that isn't developing normally.
What Causes a Miscarriage?
The cause of many miscarriages cannot be identified, but there are a few known reasons for miscarriage.
Most miscarriages, especially those that occur in the first trimester, are due to random chromosomal abnormalities with the baby and cannot be prevented. Other reasons for miscarriage may be:
- problems with the implantation of the fertilized egg
- maternal problems with health, hormones, or infection
- unhealthy lifestyle (smoking, drugs, excessive caffeine, malnutrition, exposure to radiation)
- maternal age
- maternal trauma
Does One Miscarriage Increase the Likelihood of Another?
In general, a single miscarriage doesn't mean that a woman is doomed to multiple miscarriages. A woman who miscarries only has a slightly higher risk (25%) of having a miscarriage than a woman who has never miscarried (20%).
Vaginal Bleeding in Pregnancy
While vaginal bleeding during pregnancy is always present during miscarriage, it doesn't always mean that miscarriage is imminent. An estimated 20% to 30% of women report some type of bleeding in early pregnancy, but only half of those who bleed end up miscarrying their pregnancies.
Causes for vaginal bleeding in pregnancy include implantation bleeding when the egg affixes to the uterine wall and reaction of a sensitive cervix to pelvic exams or sex. It is important to know that sex does not cause miscarriage.
With the high percentage of pregnancies that end in miscarriage, it's a good idea for all women who plan to conceive to educate themselves about the types of miscarriage and the facts surrounding early pregnancy loss.
Readers might also enjoy "Recovering from Miscarriage" and "What to Do if You Think You're Having a Miscarriage."
Source:
The American Pregnancy Association
