How Can the Skull Theory Tell You If Your Baby Is A Boy Or A Girl?

You imagine your child’s appearance, whether it’s your first baby or you are adding to your family. Will they have the eyes of you or your partner?
You may be too impatient to await your 20-week scan to learn if it is a boy. There’s an old rumor you can use ultrasounds taken earlier to determine the gender of your baby. Some women believe in The Skull theory, a popular urban myth, while others dismiss it. We’ll get to the bottom of it.

What is skull Theory?

The skull theory, also known as the skull gender theory, is the belief that by examining your ultrasound images from earlier in pregnancy, you can accurately determine the gender of your child.

According to a theory, the size and shape of the baby’s head can predict whether it’s a boy. Anecdotally, the skull theory is a favorite amongst pregnant women’s forums. You can find forums around the globe where moms post early ultrasound scans of their babies and encourage commenters to guess their sex.

The timing of ultrasound in skull theory

You’ll want a clear picture of your baby at 12 weeks if you use skull theory before the 20-week anatomy scan.
The skull may not be “very clear”, depending on the baby’s position in the womb when you scan.
According to supporters of the skull theory, you should position the baby in profile so that the skull can easily be measured front-to-back. Anecdotal evidence from various pregnancy forums suggests that, even with an ultrasound showing a clear image, it is not always easy to tell if you are having a boy.

Claimed skull for a boy

The skull theory speculation is that baby boys have more prominent and more blocky skulls. Boys have a more defined brow ridge and a squarer chin. They also have more angled teeth. A boy’s skull also tends to be larger and has prominent cheekbones.

Null & Skull Predictions Baby Gender Pro

Claimed skull appearance of a girl

In contrast to boys, baby girls have a rounder chin with a larger angle on their jaws. Their foreheads are also less sloping and have smaller brow ridges.


Skull Theory’s Accuracy

Even those who support the skull theory admit that accuracy ranges between 70 to 95 per cent. They also say that further research is required to confirm that this early gender test is valid. There needs to be more evidence in peer-reviewed publications.

We can see that experts in anthropology, archaeology and other scientific fields are not able to determine the gender of a child using skulls.
The skull differences listed as determining the gender of a child or a girl can only be seen in adults. These unique markers are visible on the skull of a human in puberty. When archaeological sites are excavated and human remains examined, these features can be used to determine the sex of the individual.
Skull theory is unreliable because neonatal skulls don’t show these differences.

There are more reliable ways to find out your baby’s gender


What other options do you have if you don’t want to wait for the 20-week scan?

The Ramzi Theory can be completed as early as 6 weeks of pregnancy and offers more reliable results for predicting the baby’s gender.

The Nub theory is a less popular baby gender predictor test; however, it still offers some insight into knowing the gender from 10 weeks pregnant.

The nuchal translucency scan (NT) is an optional test typically completed between the 11th to 13th weeks of pregnancy. The NT scan, a non-invasive test, is used to screen for abnormalities in your baby’s growth.

This scan measures the nuchal transparency or the amount of clear tissue at the back neck of your baby. Too much space in the neck could indicate a genetic disorder such as Down Syndrome or chromosomal anomalies that can be fatal for your baby.

Many may need to learn that an NT scan can include a blood screening to screen for chromosomal problems. This blood test is also able to accurately determine your baby’s sex.

Remember that the NT test and blood tests are optional. It may be necessary to request the NT scan and blood test unless you are older than 35 at the time of your delivery or at a higher risk for having a baby with a health problem.


There are numerous gender prediction theories out there. We’ve believe in the skull theory, but we also are aware that certain foods or how you carry your child during pregnancy can indicate sex at the same time. There are only a few ways to accurately determine your baby’s sex, and these generally require much more scientific involvement.

You can learn your pregnancy status before giving birth by getting a blood test at 20 weeks or an anatomy scan. Be prepared for surprises, even with a second-trimester ultrasound!


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