So is it a boy or a girl? Some like to keep the surprise until birth, but very few do. The majority want to know the sex of the baby as soon as possible. Sometimes out of simple curiosity, sometimes to prepare for it. As soon as possible, this usually corresponds to the second ultrasound appointment, which is between the 18th and 21st week of pregnancy. Not that fast…
But a new study, published in the journal Prenatal Diagnosis, presents a quick blood test, with a finger prick, that can determine the sex of the fetus. It would be usable and would give reliable results, from the 8th week of pregnancy.
Tests like this, called Non-Invasive Prenatal Diagnosis (NIPD) already exist. Indeed, such blood tests, currently available in the UK, are used to detect trisomy 21 in fetuses, along with two other genetic conditions.
Usually, when parents want to know if their fetus is a carrier of these genetic diseases or not, an amniocentesis is performed. This involves extracting a sample of cells from the amniotic fluid, which surrounds and protects the developing baby in the womb.
Created by a team of Brazilian researchers from the Sabin laboratory, this concept has been the subject of an experiment with 100 pregnant women. The team was looking for the Y chromosome, which therefore corresponds to the male sex, in each blood sample taken from the finger of future mothers, in order to determine whether it is a baby girl or boy.
The test results were corroborated by subsequent clinical examinations of the neonate at birth. This made it possible to affirm that they are reliable if they are carried out after the eighth week of pregnancy.
The only potential problem is that these blood samples can be "contaminated" with foreign DNA present on the surface of the finger, which can lead to false results.
