Mayo Clinic Health Manager
Get free personalized health guidance for you and your family.
Get Started
About our e-newsletters
- Free e-newsletters
- Mayo Clinic expertise
- We do not share your e-mail address
Housecall, our weekly general-interest e-newsletter, keeps you up to date on a wide variety of health topics with timely, reliable, practical information, recipes, blogs, questions and answers with Mayo Clinic experts and more. Our biweekly topic-specific e-newsletters also include blogs, questions and answers with Mayo Clinic experts, and other useful information that will help you manage your health.
Housecall Archives
Mayo Clinic Housecall
Stay up to date on the latest health information.
What you get
- Free weekly e-newsletter
- Mayo Clinic expertise
- Recipes, tools and other helpful information
- We do not share your e-mail address
Why it's done
By Mayo Clinic staffAmniocentesis is done for different reasons at different stages of pregnancy.
Genetic amniocentesis
Genetic amniocentesis can provide information about your baby's genetic makeup. Generally, genetic amniocentesis is offered when the test results may have a significant impact on the management of the pregnancy — or your desire to continue the pregnancy. Often, the value of this information can only be assessed by you and your partner.
Genetic amniocentesis is usually done after the 15th week of pregnancy, when the two layers of fetal membranes have fused enough to safely withdraw a sample of amniotic fluid. Rarely, genetic amniocentesis may be done as early as the 11th week of pregnancy.
You may consider genetic amniocentesis if:
- You had abnormal results from a prenatal screening test. If the results of a screening test — such as the first trimester screen or quad marker screen — are positive or worrisome, you may opt for amniocentesis to confirm or rule out a diagnosis.
- You had a chromosomal abnormality or neural tube defect in a previous pregnancy. If a previous pregnancy was affected by Down syndrome or a neural tube defect — a serious abnormality of the brain or spinal cord — this pregnancy is at higher risk, too.
- You're age 35 or older. Babies born to women age 35 and older have a higher risk of chromosomal abnormalities, such as Down syndrome.
- You have a family history of a specific genetic disorder, or you or your partner is a known carrier of a genetic disorder. In addition to identifying Down syndrome and spina bifida, amniocentesis can be used to diagnose many other conditions — including cystic fibrosis, hemophilia and sickle cell disease. This requires specialized testing of the amniotic fluid, however, so there must be a reason to test for these conditions.
- You have a suspected uterine infection or Rh incompatibility. Less often, amniocentesis is used to diagnose uterine infections or Rh incompatibility — an uncommon condition in which a mother's immune system produces antibodies against a specific protein on the surface of the baby's blood cells.
Maturity amniocentesis
Maturity amniocentesis can determine whether a baby's lungs are ready for birth. This type of amniocentesis is only done if early delivery — either through induction or C-section — is being considered to prevent pregnancy complications for the mother. It's usually done between the 32nd and 39th weeks of pregnancy. Earlier than the 32nd week, a baby's lungs aren't likely to be fully developed.
Other reasons for amniocentesis
Occasionally amniocentesis is used to evaluate a baby for infection or other illness. Rarely, amniocentesis is used to decrease the volume of amniotic fluid.
