Most pregnant women are in doubt about how many weeks they can do fetal sexing.

The miracle of life enchants us all. One of the most exciting parts of pregnancy is finding out the gender of the unborn baby.

Fetal sexing then emerges as an incredible tool, making this revelation possible at an early stage of pregnancy.

But the big question is: how many weeks can you do fetal sexing? Let’s answer that question and explore more about this fascinating process over the course of our chat.

What is Fetal Sexing?

Fetal sexage is a blood test performed by the pregnant woman in order to find out the sex of the baby.

It analyzes the fetal DNA present in the mother’s blood, looking for the Y chromosome. If found, the baby is male; if not, it is female.

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Comparing fetal sexing with other sex determination methods

Why do fetal sexing?

Fetal sexing is not just a method to satisfy parents’ curiosity.

It can be useful in the early detection of some sex-linked genetic diseases, such as hemophilia and Duchenne muscular dystrophy.

And because it is such an effective and popular test, many mothers are left with the question of how many weeks they can do fetal sexing.

At how many weeks can you do fetal sexing?

In short, fetal sexing can be done from the 8th week of pregnancy.

However, to increase the accuracy of the test, it is recommended to wait until the 10th week.

Since this way, maternal blood contains more fetal DNA, which improves the analysis.

How to prepare for the fetal sexing exam?

There are several methods for determining the sex of an unborn baby, but each has its own unique characteristics, for example:

  • Fetal sexing, performed from the 8th week of gestation onwards, stands out for its accuracy of over 99% and for being a non-invasive procedure. It consists of analyzing the fetal DNA present in maternal blood, looking for the Y chromosome;
  • Ultrasonography, a widely used method, allows you to view the baby directly. However, sex determination using this method is usually only possible after the 16th week of pregnancy, when the baby’s genitals are already more developed. The accuracy of this method depends on the baby’s position at the time of the examination;
  • Amniocentesis, which involves collecting amniotic fluid, can accurately determine the sex of the baby, but it is an invasive procedure and usually reserved for testing for genetic disorders. It is commonly performed between the 15th and 20th week of pregnancy.

Therefore, fetal sexing appears as an attractive option, especially for those parents who want to find out the baby’s sex early and safely.

However, the choice of method should always be made in consensus with a health professional, taking into account the individual clinical condition of the pregnant woman.

Interpreting fetal sexing test results is a fairly straightforward process. This test looks for the presence of the Y chromosome in maternal blood, which is indicative of a male baby.

If the Y chromosome is detected, the result will be male positive. It indicates that you are expecting a boy.

On the other hand, if the Y chromosome is not detected, the result will be negative for the male, which indicates that you are expecting a girl.

It is important to highlight that, although the accuracy of fetal sexing is greater than 99% when performed after the 10th week of pregnancy, there is always a small possibility of error. This can occur, for example, if the mother had a previous pregnancy with a boy, which can leave traces of the previous fetus’s DNA in the mother’s blood.

Therefore, although fetal sexing provides a very accurate indication of the baby’s sex, it is always recommended to discuss the results with your doctor or healthcare professional for a complete and correct interpretation.

Where to do the fetal sexing test?

The fetal sexing test can be performed in several specialized clinical analysis laboratories.

For example, the examination of fetal sexing in Lavoisier It is one of the most frequently performed exams at the Santo André unit, in the ABC region of São Paulo.

Procedures may vary slightly from location to location, but generally involve a simple blood draw from the mother.

It is worth remembering that it is essential to choose a reliable laboratory recognized for the quality of the service provided.

This will ensure the accuracy of the results, contributing to the safety and peace of mind of the pregnant woman.

Prior consultation with a doctor or health professional can help in choosing the most appropriate laboratory to perform the fetal sexing test.

Common questions

See the most common questions about fetal sexing.

Is Fetal Sexing 100% Accurate?

In most cases, yes. The accuracy of the test is 99%, provided it is performed after the 10th week of pregnancy.

Is fetal sexing an invasive procedure?

No, fetal sexing is a simple, non-invasive blood test.

Are there risks for the mother or baby?

No. As it is just a blood test, there are no risks associated with fetal sexing.

Can the result of fetal sexing be influenced by a previous pregnancy?

Yes. If the mother has had a boy before, there may be remnants of the first baby’s DNA in her blood. This can influence the result.

How long does it take to receive the result of fetal sexing?

Fetal sexing results are usually available within one to two weeks of the blood draw.


Many mothers don’t know how many weeks they can do fetal sexing, which is normal.

Fetal sexing is a revolutionary technique that makes it possible to know the sex of the baby at an early stage of pregnancy.

With information about how it works, parents-to-be can make more informed decisions and prepare for the arrival of their new family member.


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