Miscarriage and Stillbirth Risk in Down Syndrome

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You've probably heard of Down syndrome, but you may not know that there's an increased miscarriage and stillbirth risk with this disorder.

Down Syndrome 

Down syndrome is a chromosome abnormality that causes intellectual, health, and physical problems in babies who are born with it. There is no cure, though therapies and other treatments make the condition more manageable for people living with it.

It's usually caused by random genetic errors. That means it's not typically inherited from a parent's genetic makeup. We normally have 46 chromosomes. When there is an extra copy of chromosome 21, this is called trisomy 21. Trisomy 21 causes most cases of Down syndrome. If you are over 35 years old, your odds of having a baby with a chromosome disorder such as Down syndrome are increased, but the odds of having a baby without a chromosome disorder are higher.

Down syndrome is the most common genetic condition. It occurs in 1 in every 700 babies born in the United States, according to the National Down Syndrome Society.

The Risk of Miscarriage

About 6,000 babies are born in the U.S. with Down syndrome every year. However, a Down syndrome diagnosis can cause miscarriage and stillbirth. It's estimated that between an amniocentesis (done between 15 to 20 weeks of pregnancy) and delivery, up to 30 percent of Down syndrome pregnancies that are not terminated result in miscarriage or stillbirth.

The pregnancy loss rates differ based on the mother's age and on how early Down syndrome is detected. (Timing of detection tends to depend on whether chorionic villus sampling [CVS] or amniocentesis were used).


A British study of Down syndrome pregnancies found:

  • The average fetal loss rate between the time of CVS and term was 32 percent, increasing from 23 percent for women aged 25 to 44 percent for women aged 45.
  • The average fetal loss rate between the time of amniocentesis and term was 25 percent, increasing from 19 percent to 33 percent across the same age range.

Aside from maternal age, researchers do not know why some Down syndrome pregnancies are miscarried or stillborn, while others continue on to live birth. Experts suspect that growth restriction and severe structural abnormalities in the fetus may lead to the condition being incompatible with life.

If you have learned that your pregnancy is affected by Down syndrome, you do face an increased risk of pregnancy loss. You may be referred to a high-risk pregnancy specialist for increased monitoring for the duration of your pregnancy.

After a Miscarriage

If you had a miscarriage and chromosome testing indicated Down syndrome as the cause, you should know that the pregnancy loss was not your fault.

Most chromosome disorders, including Down syndrome, are believed to be the result of random problems in cell division. In the small number of inherited cases, there's still nothing you could have done differently to prevent what happened.

According to the March of Dimes, if you have one pregnancy affected by Down syndrome, your risk of another Down syndrome pregnancy is 1 in 100 until you turn 40 years old. At that point, your risk is based on your age. 

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