Q&A: I would like to know more about amniocentesis.

An amniocentesis is a special pregnancy diagnostic test most commonly preformed between week 16 and week 20 of pregnancy. This test is done by taking a small sample of the amniotic fluid (the fluid your unborn baby is floating in) to check on your baby's development and to screen for certain chromosomal abnormalities, including Down syndrome.

This is not a routine test. It is suggested primarily to women who are at risk of having a baby with abnormalities. Factors considered when deciding on the need for an amniocentesis include:

• Your age (if you're over 35)
• Your family history
• If you've had positive results from a nuchal fold test done before the week 14 of pregnancy.

The test is done using ultrasound to guide your doctor as she inserts a very thin needle into your abdomen. The needle enters the uterus and withdraws a small amount of amniotic fluid. The fluid obtained from this test is then sent to a laboratory for testing. It can take up to 10 to 12 days for the results to be available. This is an invasive test, so it does carry with it a small risk of miscarriage. However, according to ACOG (the American College of Obstetricians and Gynecologists), the risk of miscarriage is about one percent, and complications are uncommon. Cramping, spotting, or leaking of amniotic fluid may occur after the procedure. If you have questions or concerns, talk with your doctor before deciding on whether or not you want to have this test.