BACKGROUND: Detection of cell-free fetal DNA (cffDNA) in maternal plasma has 
given rise to the possibility of new non-invasive approaches for early prenatal 
diagnoses. We evaluated the feasibility and accuracy of non-invasive fetal 
gender determination using quantitative fluorescent-polymerase chain reaction 
(QF-PCR) analysis of circulating cffDNA in the first-trimester maternal plasma.
METHODS: Plasma samples were prospectively collected from 202 singleton 
pregnancies at 4 to 13 weeks of gestation. Fetal gender was determined by QF-PCR 
with the sex-determining region Y (SRY) and amelogenin X/Y (AMELX/Y) genes. The 
result was confirmed by fetal karyotyping or phenotype at birth.
RESULTS: Of the 202 pregnancies, 162 had pregnancy outcomes available and could 
be included in our evaluation. The accuracies of AMELX/Y, SRY, and combined 
AMELX/Y+SRY analysis for fetal gender determination were 83.3%, 82.1%, and 
97.5%, respectively, compared with those of the invasive approach and the fetal 
gender outcome at birth (82 males and 80 females). Combined AMELX/Y+SRY analysis 
had the highest sensitivity (98.8%) for fetal gender determination with a 
specificity of 96.3%. Moreover, fetal gender detection by the combined 
AMELX/Y+SRY analysis at 11 to 13 weeks of gestation was 100% correct.
CONCLUSION: Fetal gender determination could be accurately determined from 
maternal cffDNA in the first-trimester using QF-PCR analysis of combined 
AMELX/Y+SRY.