What are the risks of amniocentesis?

Amniocentesis does carry a risk of miscarriage or major complications in 1-in-200 to 1-in-400 pregnancies. Complications include bleeding, leakage of amniotic fluid, and infection. The risk of complications increases slightly if an amniocentesis is performed around 12 to 14 weeks of pregnancy instead of the standard 15 to 18 weeks. In general, some women experience cramping or discomfort after an amniocentesis. Most experience no problems.

Amniocentesis is generally very safe. There is a chance (about 1 out of 400) that this test may cause a miscarriage. 1 In some studies, the risk is a little higher, about 2 to 4 out of 400. 2 There is also a risk of too much bleeding (hemorrhage), infection of the amniotic fluid (amnionitis), or leakage of amniotic fluid. In very rare cases, a fetus may be poked by the needle during the test. Your doctor does all he or she can to put the needle in a safe spot. Most fetuses float away from the needle tip.

Amniocentesis has a very small risk of causing bleeding that could lead to mixing your blood and your fetus's blood. So if you have Rh-negative blood, you will be given the Rh immunoglobulin vaccine (such as RhoGAM) to prevent Rh sensitization, which could harm your fetus if he or she has Rh-positive blood.

After the test, you may have some mild cramping. You should not do any strenuous activity for several hours after the test. Also, do not douche, use tampons or have sex after the test. By the next day, you can do your normal activities, unless your doctor tells you not to.

Call your doctor right away if:

• You have moderate or severe belly pain or cramping.
• You develop a fever.
• You become dizzy.
• Fluid or blood leaks from your vagina or from the needle site.
• Redness or swelling develops at the needle site.