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Fetal sex determination

Fetal sex determination, i.e. finding out whether the baby is a boy or girl, is a relatively simple procedure. Knowing the sex of the fetus does not tell you if it is affected by hemophilia, but it does provide useful information.

If the fetus is male, CVS or amniocentesis can be offered to parents who wish to know whether he is affected with hemophilia. If a carrier chooses not to have CVS or amniocentesis, or if these tests are not available, doctors should plan labour and delivery to minimize the chance of bleeding in a male fetus

If the fetus is female, prenatal diagnosis is not necessary because, even if the female child is a carrier, there is very little risk of bleeding for the baby during labour and delivery.

The sex of the fetus can be determined in two ways:

  • Fetal sex typing from maternal plasma: A blood sample is taken from the mother from as early as eight weeks of pregnancy. The sex can be determined from the fetus’ genetic material, which is found in the mother’s blood. This procedure can be done in the first trimester of pregnancy but is only available in specialist units.
  • Ultrasound scan: The sex of a fetus can be accurately determined by ultrasound from 15 weeks of pregnancy. At this gestational age, amniocentesis is the preferred option to determine if a male fetus is affected with hemophilia.


Updated November 2012