How to Know Baby's Gender Scientifically?

Fetal sex diagnosis means the determination of baby gender by using medical, biological and genetic theories, polymerase chain reaction, fluorescence quantitative analysis, etc. to isolate DNA chromosomes thru multiple centrifugalizations and to detect the presence of Y chromosome in the blood sample.

Chorionic Villus

Villus test, also known as chorionic villus sampling (CVS), is to lead a slender needle under the ultrasound guidance into the amniotic cavity through the abdomen, uterine wall and amnion of the pregnant woman and to extract a small amount (about 20CC) of amniotic fluid. The amniotic fluid around the embryo is surrounded by the amniotic membrane and it contains many cells sloughed from the embryo's skin, respiratory, digestive and urinary mucosa for test. Generally, the CVS is carried out after the 10th gestational week. It has been 30 years since the first amniotic fluid cell was cultured successfully in 1968. However, the CVS has the risk of miscarriage or fetal malformation.

Just like amniocentesis, the chorionic villus sampling is used to diagnose whether the embryo's chromosomes are normal or to determine the sex of the fetus. The CVS has an accuracy of up to 100% and the result can be yielded within two days. Although the fetus's sex can be determined at about the 10th gestational week by using chorionic villus sampling, the technique may cause abortion (1% possibility of harming the fetus).

Maternal Blood DNA

Maternal blood test is to identify the sex of the fetus by using the cell morphology technique: a few drops of peripheral blood, i.e. capillary blood of the expectant mother is sampled from her earlobe to make a blood smear for special staining. This test is rather safe and more than 95% accurate and it can be carried out after the 45th gestational day. The maternal blood test does not cause miscarriage or fetal malformation.

B-mode Ultrasound

To determine the fetus's sex with B-mode ultrasound, the gestational period must be at least 19 weeks. Even the most experienced imaging experts can only tell the baby gender after 3.5 months or 3 months of pregnancy and it is not 100% accurate but the safest method.


Amniocentesis is an invasive method for sex determination and has the risks of 1% to 3% abortion, fetal malformation, and infection. The accuracy is up to 95%. Amniotic fluid, a special fluid reflecting fetal functions and certain diseases, contains cells sloughed from skin, respiratory tract and urinary tract of the fetus. Medical circles disapprove amniocentesis for the purpose of determining the fetus's sex. Amniocentesis is to detect the fetus conditions by extracting the amniotic fluid from the amniotic cavity of a pregnant woman with a long needle.

Chinese Law about Sex Determination

On May 1st , 2016, the regulation of the prohibition of sex determination and sex-selective abortion are implemented. Doctors are forbidden by the state from exposing the sex of unborn babies to stop prospective parents from finding out the gender of their child and potentially abort or abandon babies.