Miscarriage Statistics by Week

expectant couple

According to the Mayo Clinic, between 15 and 20 percent of known pregnancies end in miscarriage. However, it is important to consider that many women will miscarry before they even realize they are pregnant and may simply mistake the miscarriage for an unusually heavy menstrual cycle. Therefore, the actual number of pregnancies that end in miscarriage is likely much higher.

Understanding Miscarriage

Miscarriages generally occur fairly early in a pregnancy. Baby Center reports that more than 80 percent of pregnancy losses happen before 12 weeks. The Miscarriage Support Network says that the highest risk period for a miscarriage is between four and six weeks gestation. Once you can see a heartbeat on the ultrasound, your risk of miscarriage continues to drop each day.

A miscarriage can be caused by a number of factors and sometimes doctors can offer no concrete explanation for why a woman has a miscarriage. However, you can consider the following statistics:

  • Duke University researchers say random chromosomal error is responsible for about 70 percent of miscarriages before six weeks of gestation.
  • According to the Mount Sinai School of Medicine, age plays a significant role in miscarriage risk. Women age 35 have a 25 percent chance of miscarrying in the first six weeks, while women age 40 have a 42 percent chance of miscarrying.
  • The Mayo Clinic reports that about 50 percent of miscarriages occurring before 12 weeks gestation are caused by a blighted ovum. This occurs when a fertilized egg develops a placenta and a membrane, but has no embryo.

If you would like to learn more about miscarriage, please review the following articles from LoveToKnow Pregnancy:

Stillbirth Statistics

After 20 weeks, a pregnancy loss is referred to as a stillbirth instead of a miscarriage. MedicineNet.com reports that stillbirths occur in approximately 1 in 200 pregnancies in the United States.

About half of all stillbirths appear to have no known cause. However, The March of Dimes reports that some of the possible risk factors for a stillbirth include:

  • High blood pressure
  • Diabetes
  • Smoking
  • Obesity
  • Multiple pregnancy
  • African American ancestry

Repeated Pregnancy Loss

Doctors often stress that one miscarriage does not indicate that a woman will be unable to carry a pregnancy to term. In fact, the vast majority of women who suffer from a miscarriage will go on to later have healthy pregnancies. According to the Mayo Clinic, 60 to 70 percent of women who have a miscarriage will be able to have a healthy pregnancy at a later date. If there is a recognizable and treatable cause of the miscarriage, the number increases to 90 percent.

Evaluating Your Personal Risk

When looking at miscarriage statistics by week, it is very important to remember that statistics are calculated using the general population as a whole. This includes women of all ages, as well as women with health problems and women who have not had access to proper prenatal care.

Your personal risk of having a miscarriage depends upon factors such as your age, overall health, and previous medical history and can't be calculated using general statistics. If you have concerns about your pregnancy, it is best to discuss this issue with your healthcare provider.

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Miscarriage Statistics by Week