Telling a fetus’ sex is not always easy. If it’s old enough, a sonograph will show the obvious signs, but what do you do before then? Up until now, the gold standard has been cytogenetic determination — an invasive blood test on the baby. However, it seems there’s a much easier way, and it doesn’t touch the baby at all.
While carrying the child, the mother’s blood has cell-free fetal DNA floating around in it, and it’s possible to use this to test for the baby’s sex. In a meta-analysis that covered more than 6,000 pregnancies, the test was found to be 95% efficient in guessing the sex of the fetus — and it works from as early as seven weeks. As the fetus and the placenta develop, the amount of DNA present in the mother increases, boosting the accuracy of the test, which hits its peak at 20 weeks.
This method is apparently already widespread in Europe, but America hasn’t adopted the practice yet — despite the fact that it could mean a faster, easier way to find out the sex of your baby. All it takes is a dab of blood.
The real question is whether there’s enough of the fetal DNA in the mother’s system to test for chromosomal abnormalities, which would allow for other kinds of genetic testing that are arguably more important to the future baby’s health.
