The Nub Theory: Can You Really Predict Your Baby’s Gender at 12 Weeks?

For many expectant parents, the excitement of pregnancy often comes with a bit of playful curiosity — and one of the most common questions is, “Am I having a boy or a girl?” While traditional scans usually reveal this around 18-20 weeks, a popular method called nub theory claims you might get a clue much earlier.

So, what exactly is nub theory?

Around the 12-week mark, babies in the womb have a small, visible protrusion between their legs, often referred to as the nub. According to this theory, the angle and direction of this nub can hint at whether you’re expecting a boy or a girl.

• If the nub is angled upward, more than about 30 degrees in relation to the spine, it’s said to suggest a boy.

• If the nub is flat or pointing downward, it’s often guessed to be a girl.

These predictions are usually based on ultrasound images from the dating scan, and while some parents swear by it, nub theory is only guaranteed when actual nub theory specialists predict with your scan images. Mostly, trained professionals will get it wrong at this early stage, they usually mistake the nub for leg or cord and will tell you it isn’t accurate. They are trained in your baby’s health, not sexing a baby.

Why Do People Love the Nub Theory?

It’s simple — it adds a bit of harmless fun to the waiting game. Whether shared in online communities, discussed among friends, or just a private guess between partners, trying to “read the nub” is a way to feel more connected to the baby and build excitement for what’s to come.

But Does It Really Work?

There have been small studies which show the nub theory is accurate, as long as full nub is inaging and gestational age is 12 weeks plus. Factors like the baby’s position, the quality of the scan, and the experience of the person analysing it all make a difference.

The Bottom Line

The nub theory is a fun, speculative way to pass the time during those early pregnancy weeks. Nub theory can definitely add some extra excitement before you get official news, however be sure to go to those who actually know what they’re doing. Many FB groups provide free nub theory analysis, however many will mistake a “stacked nub” and predict a boy! A nub will be captured in many different shapes due to the movement of baby in the womb. It’s so important the nub is analysed properly, for the results to be accurate.

Whether baby is a boy or a girl, the real surprise is meeting your little one in person!