Amniocentesis: Understanding the risk, benefits, and timing

During amniocentesis, your healthcare provider takes a sample of your amniotic fluid to gather information about the health of your baby. The sample is removed using a fine needle and with the assistance of ultrasound.

An amniocentesis can help diagnose a variety of conditions, but is it a necessary diagnostic test for all pregnant women? What are the potential benefits or risks associated with the procedure?

Why is an amniocentesis performed?

This prenatal test is commonly performed to determine if there is a risk your baby has a genetic disorder, chromosome abnormality or neural tube defect. These conditions include:

• Spina bifida
• Cystic fibrosis
• Down Syndrome: aka Trisomy 21

While an amniocentesis is usually performed in the second trimester, it can also be performed in late pregnancy to diagnose other problems, including:

• Infections
• Lung maturity
• Rh disease: blood type incompatability problems

Reasons to consider amniocentesis

Your doctor may recommend an amniocentesis if you are at an increased risk for bearing a child with birth defects or chromosome abnormalities. This includes women who:

• Are over the age of 35
• Have a family history of a specific genetic disease, metabolic or chromosomal disorder
• Have a partner who is a carrier of a genetic condition
• Had positive results from another prenatal screening test
• Had a previous child or pregnancy with a birth defect

What are the benefits of amniocentesis?

The primary benefit of this procedure is to validate the diagnosis of an abnormality that has been found with another prenatal test. It is also possible for amniocentesis to show that your baby does not have an abnormality that was initially suspected. In either circumstance, this prenatal test allows you to consider all options available to you and plan the rest of your pregnancy.

Are there any risks involved?

Women who have had an amniocentesis may experience leaking of amniotic fluid, cramping or bleeding. In rare cases, an infection may occur. The risk of miscarriage is also increased with amniocentesis. According to Johns Hopkins Medicine, this risk is less than 1 percent and is only marginally higher than the typical risk of miscarriage associated with women who are in their second trimester of pregnancy. If you are considering amniocentesis, discuss your questions and concerns with your doctor.