When is the sex of the fetus formed?

The article was professionally consulted by Specialist Doctor I Truong Nghia Binh - Obstetrician-Gynecologist - Department of Obstetrics and Gynecology - Vinmec Da Nang International General Hospital.

The formation of fetal sex will occur at the time the egg and sperm meet, according to the principle: egg carrying X chromosome meets sperm carrying X chromosome will form XX zygote - female sex still egg An X-carrying spermatozoon meets a Y-bearing sperm to form an XY - male zygote.
Although fetal sex is formed from the moment the egg and sperm meet, however, it is not until the 9th week of pregnancy that the fetus's sex organs develop differently, helping to detect by ultrasound at 12 weeks onwards.

When an egg carrying an X chromosome meets a sperm carrying an X chromosome, an XX zygote will form, which means the baby's sex is female. Under the influence of female sex hormones (mainly in the presence of Estrogen), the testicular differentiation gene SRY is inactivated, therefore, the external genitalia develops: The genital tubercle will appear in the middle of the region. bipedal tissue and develop into the female genitalia, or clitoris. Simultaneously with this process, the urogenital folds on both sides of the clitoris will form the inner lip (small lip), making the vagina open. In particular, this fold also forms the pelvis because it is joined together on the underside. The outer lip, also known as the labia majora, will be formed due to the enlargement of the Labiosrotal folds.
When the fetal sex is female, the ovaries will fully develop at 22 weeks of pregnancy and move from the abdomen to the pelvis, there will be about 6 initial symptoms, when the baby is born, it will decrease to 1 to 2 million eggs, entering puberty the number of eggs is only about 300,000 to 400,000 eggs.

The male fetus will form external genitalia due to the presence of the male sex hormone Dyhydroterstoterone (DHT) produced by the testes. An X chromosome and a Y chromosome produce testosterone, which promotes the growth of genital mounds into male sex organs. By the 12th week of pregnancy, the genital tubercle will develop into a penis and lengthen, the foreskin is also formed at this time, the body of the penis is also formed by two urogenital folds moving close together. than. The scrotum (where the testicles are located) is formed when the Labiosroltal folds meet, the Raphe line is the line between these two folds. Testicles are formed in the abdomen, by the 7th or 8th month of pregnancy, the testicles will move down into the scrotum permanently.

Science has proven that the father will completely determine the sex of the fetus, however, the time of intercourse, the environment of conception is in the mother's body, the time of conception... directly affect the sex of the fetus.
The alkaline environment in the mother's body is ideal for Y sperm to develop and fertilize. Therefore, in the first 3 months, if the mother tends to add foods containing a lot of alkali such as sausages, oranges, melons, etc., the formation of the fetus's sex may be male. On the contrary, if the mother adds foods rich in magnesium and calcium such as vegetables, soybeans, tomatoes, carrots, eggs, etc., the vaginal environment will be acidic and an ideal environment for X sperm to develop. development, the sex of the fetus can be female.
The older a man is, the lower his sperm count will be. The quality of the Y sperm will also decrease much compared to the X sperm. In particular, the aging process in a woman can affect the formation of sex. Fetal age will affect the excretion of alkaline compounds in the uterus.
The closer the time of intercourse to ovulation, the higher the chance of having a boy, and vice versa, having sex on days far from the day of ovulation, the probability of having a girl is high.

In fact, there are many methods that can be used to determine the sex of the fetus, but all are guesswork, passed on from person to person. Currently, with the development of modern medicine and technology, there are medical techniques to help determine the sex of the fetus accurately such as: Fetal ultrasound (the most accurate result from 18 to 20 weeks of pregnancy) , placental biopsy (in addition to determining the sex of the fetus, this technique also helps detect chromosomal abnormalities in the fetus), blood test ...
Knowing the formation of the fetus's sex will help parents have a better way to take care of and prepare to welcome their baby. However, the most important thing is that the fetus is healthy, born safely, the baby born whether it is a boy or a girl is still an angel that needs to be cherished and cared for carefully.
Usually, to determine the sex of the fetus, pregnant women often use fetal ultrasound. However, the accuracy will depend a lot on modern equipment and the qualifications of the doctor. Therefore, you should go to reputable medical facilities for examination.
Vinmec International General Hospital is a high-quality medical facility that is highly appreciated by customers for its quality of examination and treatment as well as professional services. Vinmec has the most modern equipment system, with the most advanced ultrasound machines in the world and a team of experienced obstetricians in diagnosing fetal sex.
In addition, to protect the health of mother and baby comprehensively, Vinmec offers a variety of package Maternity services. With this package, pregnant women will have regular prenatal check-ups with specialist doctors. Perform prenatal and postnatal screening tests for the baby. During pregnancy, if a pregnant woman encounters any abnormal health problems, she will be consulted and treated by a specialist doctor. After each visit, the doctors will analyze the ultrasound and test results and advise on health care, nutrition, and rest suitable for each pregnant woman, helping the mother and fetus to be healthy. well developed, uniform indicators.
If you have a need to use maternity services at Vinmec, please register directly at the website to be served.