Couples who have conceived naturally may wish to know whether their child is affected by hemophilia before he or she is born. A definitive prenatal diagnosis can only be offered with invasive procedures such as amniocentesis or chorionic villus sampling. The risk of miscarriage associated with CVS or amniocentesis is up to 1 per cent.
Some centres only offer these procedures if the couple plans to terminate the pregnancy if the fetus is found to have hemophilia. The decision to terminate a pregnancy is an extremely difficult one, which may not be acceptable for religious, ethical, or cultural reasons.
Prenatal diagnosis methods
- Chorionic villus sampling (CVS): Under local anesthesia and ultrasound guidance, a fine needle is inserted through the abdomen or a thin catheter is inserted through the mother’s vagina to take a sample of chorionic villi cells from the placenta. These cells contain the same genetic information as the fetus itself, and can be used to determine whether the fetus is affected by hemophilia. CVS is carried out early—between 11 and 14 weeks of pregnancy. It is the most widely used method for the prenatal diagnosis of hemophilia and other inherited bleeding disorders.
- Amniocentesis: A small amount of amniotic fluid is removed, using a fine needle inserted into the uterus through the abdomen. Amniocentesis is done under ultrasound guidance, between the 15th and 20th week of pregnancy. The amniotic fluid contains cells from the fetus that can be analyzed to detect hemophilia.
Updated November 2012