Though amniocentesis is usually performed safely and successfully, the procedure carries several potential risks. Women and their partners need to weigh these risks against the possible benefits of an amniocentesis. Possible risks include:

• Membrane rupture. Loss of amniotic fluid is more common in women who undergo amniocentesis than in those who do not. This usually stops within a week after the test, but in rare cases, it can continue. If this happens, the mother and fetus will be closely monitored for signs of adverse effects, such as infection or abnormal growth of the fetus. A continuing fluid loss raises the risk of several complications, including:
  
  
• Preterm delivery
• Skeletal deformities
• Lung problems in the fetus
• Death of the fetus
  
  
• Indirect injury to the fetus. Some studies have indicated that amniocentesis may raise the risk of various types of injury to the fetus. Although the link has not been confirmed, it is believed that fetal injuries related to amniocentesis may include clubfoot, hip dislocation and respiratory problems.
  
  
• Infection of the amniotic fluid. This is very rare, but it usually results in loss of the pregnancy. Studies have indicated a possible – though unconfirmed – link between amniocentesis and the transmission of infection from the mother to the fetus. Examples of these infections include:
  
  
• HIV. The virus that causes AIDS.
  
  
• Cytomegalovirus. Any of a group of herpes viruses that attack and enlarge epithelial cells.
  
  
• Hepatitis C. Infection of the liver.
  
  
• Toxoplasmosis. An infection caused by parasites. When contracted by a pregnant woman, it can result in serious damage to the fetus.
  
  
• Miscarriage. In rare cases, an amniocentesis can result in the death of the fetus. This risk may be increased when other circumstances are present, including:
  
  
• Bleeding during the pregnancy
• High levels of maternal serum AFP (alpha-fetoprotein)
• Previous miscarriage
• History of multiple abortions  
  
  
The risk of miscarriage is between one in 400 and one in 200 procedures, according to the Centers for Disease Control and Prevention. Some studies have indicated that the risk of miscarriage is far higher during early amniocentesis (performed during the first trimester) than in second-trimester procedures.