To the untutored (and often the tutored) eye, it can be hard to guess a baby's sex from an ultrasound scan. A simple blood test could predict the sex quickly and easily in the first trimester, long before the images on the screen are clear.
The baby's DNA shows up in the mother's blood. South Korean researchers looked at plasma from 203 women between 5 and 12 weeks of pregnancy and looked for fetal DNA that codes for two enzymes, DYS14 and GAPDH. They linked the ratio of the two enzymes with sex after birth. The results are published in The FASEB Journal.
"Generally, early fetal gender determination has been performed by invasive procedures such as chorionic villus sampling or amniocentesis. However, these invasive procedures still carry a one to two percent risk of miscarriage and cannot be performed until 11 weeks of gestation. Moreover, reliable determination of fetal gender using ultrasonography cannot be performed in the first trimester, because the development of external genitalia is not complete," said Dr. Hyun Mee Ryu, Ph.D., a researcher involved in the work from the Department of Obstetrics and Gynecology at Cheil General Hospital and Women's Healthcare Center at the KwanDong University School of Medicine in Seoul, South Korea.
Why is this important, over and above choosing the colors of the baby's nursery? Some disorders, such as Duchene muscular dystrophy or hemophilia A and B, are sex-linked, and are vanishingly rare in female children. Knowing that she was carrying a girl before ultrasound scans can give the clues would mean that a pregnant woman could avoid invasive and potentially risky tests such as chorionic villus sampling or amniocentesis.
- read the press release
- see the abstract