PARENTS-to-be usually find out whether they are having a boy or girl around 20 weeks of pregnancy, but a review study has suggested that tests using cell-free fetal DNA obtained from the mothers blood could accurately predict fetus gender as early as seven weeks into a pregnancy. Review and analysis of previous studies have indicated that blood tests performed well, while urine-based tests appear to be unreliable. Non-invasive prenatal determination of fetal sex could provide an important alternative to invasive cytogenetic determination, which is currently the gold standard for determining sex and single-gene disorders. Amniocentesis has small but measurable rates of procedure-related pregnancy loss; and sonography can be performed as early as 11 weeks gestation to determine fetal sex, although not reliably, according to background information in the article. The availability of a reliable noninvasive alternative to determine fetal sex would reduce unintended fetal losses and would presumably be welcomed by pregnant women carrying fetuses at risk for disorders, the authors write. TOI