OBJECTIVE: Couples with a risk of transmitting X-linked diseases included in a 
preimplantation genetic diagnosis (PGD) center need early and rapid fetal sex 
determination during pregnancy in two situations. The first situation 
corresponds to control of embryo sexing after PGD, the second one being that of 
couples in PGD program having a spontaneous pregnancy. Determination of fetal 
sex can be achieved by karyotyping using invasive procedures such as chorionic 
villus sampling (CVS), amniocentesis or cordocentesis and by non-invasive 
procedures such as ultrasound (US) examination. CVS is the earliest invasive 
procedure for fetal sex determination and molecular analysis of X-linked genetic 
disorders during the first trimester but it is associated with a risk of fetal 
loss. US allows reliable fetal sex determination only during the second 
trimester. Recently, reliable non-invasive fetal sex determination was realized 
by using SRY gene amplification in maternal serum.
PATIENTS AND METHODS: We report the prospective use of fetal sex determination 
in maternal serum in our PGD center. Management of pregnancies was performed 
using this non-invasive procedure in four cases of embryo sexing control and 
nine cases of spontaneous pregnancies in couples included in PGD program for 
X-linked diseases.
RESULTS: Fetal sex results using SRY gene amplification on maternal serum were 
in complete concordance with fetal sex observed by cytogenetic analysis or US 
examination, as well as at birth.
DISCUSSION AND CONCLUSION: This new strategy allowed rapid sex determination 
during the first trimester and permitted to avoid performing invasive procedures 
in nine pregnancies.