When can we know the sex of the child?

The question of when one can know the sex of the child concerns many future parents. It is perfectly natural to want to know if one is going to have a boy or a girl. This allows for better preparation for the arrival of the baby, to choose a name, to arrange the nursery, and to select clothing. In this article, we will see at which week the baby's sex is visible, what methods can be used to determine it, and to what extent they are reliable.

At what week is the baby's sex visible during pregnancy?

The determination of the sex of the fetus depends on many factors, but the most important is the stage of pregnancy and the development of the baby's sexual organs. In general, the baby's sex can be seen on ultrasound around the 12th-14th week of pregnancy, when the external sexual organs begin to form. However, at such an early stage, the accuracy of sex determination is not very high, around 70 to 75%.

Between the 16th and 18th week of pregnancy, the accuracy increases to about 85 to 90%, and the sex is determined more reliably after 20 to 22 weeks, when the fetal sexual organs are fully formed. At this stage, the accuracy of the diagnosis reaches 95 to 99%.

It is also important to consider factors such as the position of the fetus, the quality of the equipment, and the experience of the doctor: sometimes, the baby is in an uncomfortable position, making it impossible to determine the sex.

Methods for determining the sex of the child: from traditional methods to scientific methods

There are many methods to determine the sex of an unborn child. Let's look at the main ones.

Ultrasound

Ultrasound remains the most accessible and widespread method, which allows determining the sex of the child by visualizing the external genital organs. The doctor examines the genital bud, which develops into a penis in boys and a clitoris in girls.

At 12-14 weeks, the sex can be determined with an accuracy of 70 to 75%. A routine ultrasound at 19-21 weeks offers a reliability of 95 to 99% due to better visualization.

Modern cutting-edge equipment (3D/4D) allows for more accurate images.

Non-invasive prenatal testing (NIPT)

NIPT is a method of analyzing maternal blood that detects fragments of fetal DNA. It can be performed as early as the 9th-10th week of pregnancy.

If the Y chromosome is detected in the blood, it means you are expecting a boy. In its absence, it's a girl. The accuracy of this method reaches 99%.

It is mainly used to diagnose genetic abnormalities (Down syndrome, Patau syndrome, Edwards syndrome), but it also allows knowing the sex of the fetus.

Amniocentesis and chorionic biopsy

These are invasive methods performed between the 15th and 20th week of pregnancy, which involve taking biological material (amniotic fluid or placental tissue) for analysis.

The accuracy of sex determination during these examinations is close to 100%, but they carry a risk for the pregnancy and are only performed on medical indication.

Genetic analysis during IVF

During IVF (in vitro fertilization), it is possible to perform genetic diagnosis of embryos before their transfer to the uterus.

Classic IVF

The fertilization of the woman's egg by her partner's or a donor's sperm. This is a standard procedure if the woman is able to produce good quality eggs.

IVF with egg donation

This technique is used when the woman's ovarian reserve is low or the quality of her eggs is poor. Eggs from donors are used, which are fertilized by the partner's or a donor's sperm.

IVF with double donation

This method involves using eggs and sperm from a donor. It is used when both partners cannot provide their own reproductive cells.

In all these options, preimplantation genetic diagnosis (PGD) can be performed to determine the sex of the embryo and exclude any hereditary diseases.

In some countries, the choice of sex is possible for social reasons (for example, for family balance), while in others, it is reserved for medical reasons (like in Spain).

Why is it sometimes impossible to see the child's sex?

Position of the fetus

If the fetus is turned backward, has its legs folded, or is lying crosswise, it may be difficult for the doctor to visualize the sexual organs. In this case, a new ultrasound may be necessary.

Individual anatomical features

Factors making ultrasound difficult:

• the woman's pelvic features,
• thick anterior abdominal wall,
• low placenta,
• low amount of amniotic fluid,
• incomplete formation of the fetal genital organs.

Sometimes, an enlarged clitoris in a girl is mistaken for a penis, and conversely, an underdeveloped penis in a boy may be taken for female organs.

You can get an accurate ultrasound at the "natuvitro" clinic, which uses state-of-the-art devices with the possibility of 3D/4D visualization. Patients receive not only a medical report but also a video recording of the procedure.

Frequently asked questions by parents

When can the child's sex be seen for the first time?

From 12-14 weeks, sexual differences may be visible on ultrasound, but the accuracy is not higher than 70-75%. It is better to wait until 16-20 weeks.

When do we know the child's sex during a standard examination?

During the second routine ultrasound, between the 19th and 21st week. This is a standard examination when the sexual organs are already well visible.

Is it possible to know the baby's sex at an early stage?

Yes, using:

• NIPT: from the 9th week, with an accuracy of 99%,
• expert ultrasound: from the 12th-14th week, but less reliable,
• amniocentesis and chorionic biopsy: in case of medical indications.

What is the accuracy of sex determination during an early ultrasound?

At 12-14 weeks: 70-75%, from 16 weeks: 85-90%, after 20 weeks: up to 99%.