When you are about 15 weeks pregnant, your doctor may offer amniocentesis. Amniocentesis is a test that detects or rules out certain inherited disorders in a fetus. It also assesses lung maturity to see if the fetus can endure an early delivery. You can also find out the baby's gender.
Doctors generally offer amniocentesis to women with an increased risk of having a baby with particular disorders, including those who:
- Will be 35 or older when they deliver.
- Have a close relative with a disorder.
- Had a previous pregnancy or baby affected by a disorder.
- Have test results (such as a high or low alpha-fetoprotein count) that may indicate an abnormality.
Doctors also offer amniocentesis to women with pregnancy complications, such as Rh-incompatibility, that necessitate early delivery. There are blood tests and ultrasound tests that can be done earlier in the pregnancy which may avoid the need for amniocentesis at times.
Review Date 10/20/2017
Updated by: John D. Jacobson, MD, Professor of Obstetrics and Gynecology, Loma Linda University School of Medicine, Loma Linda Center for Fertility, Loma Linda, CA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.