When you are 20 weeks pregnant, it is possible to find out whether you are pregnant with a boy or a girl. Not everyone wants to know, but many women do. It is useful for decorating the nursery and for buying clothes. But from the 12th week you can already know what gender your unborn child is, if you pay close attention.
Gender development of fetus
A man and a woman bring together a sperm cell and an egg cell. The sex of the child is determined from the moment of first fertilization. A woman has chromosomes XX and a man has XY. At fertilization, each parent passes on one chromosome. The combination of these determines the gender of the child. Until the first nine to ten weeks of pregnancy, male and female embryos develop the same.
The NUB theory
The NUB theory (nub is English for ‘bulge’) looks at the protrusion that grows between the legs of both boys and girls in the first weeks. When a fetus is about 11 weeks, the protrusion starts to develop into a penis in a boy, while in a girl it develops into a clitoris with the labia around it. The child itself produces the sex hormones that influence this.
When a fetus is about 12 weeks old, but before 14 weeks old, it is possible to use the NUB to see whether you are having a boy or a girl. The NUB still looks the same in both, but they point up at a different angle. In a boy, the NUB points more upwards (an angle of approximately 30 degrees), while in a girl the NUB runs more parallel to her spine.
To be able to see this, the baby must be in the correct position during the ultrasound. He or she should lie flat on their back, with their legs raised and preferably with their right side forward. This way the protrusion is best visible. At 12-week ultrasounds the prediction is correct in 75% of the children, a week later it is even correct in 95% of the cases.
Most midwives know what the NUB theory is and you can ask them to take a photo that works for this theory. Then of course your child must cooperate.
The Skull Theory
If you are not yet completely sure about the gender of your unborn child using the NUB theory, you can also look at the skull theory. The skulls of boys and girls are not the same.
Girls have a clear forehead and at the top the head ‘suddenly’ moves back. In boys the forehead is less high, but it already slopes upwards. The transition to the top of the head is more gradual there. There are some other minor differences. For example, a boy’s skull is often more robust than that of a girl.
The Skull theory has not been proven and is only correct in about 50% of the cases. Even in adults, it is not possible to say with 100% certainty whether all skulls belong to a man or a woman. Many people dismiss it as nonsense or pregnancy nonsense. Other women swear by this theory and there are even specialists who can be asked for their opinion.
The best way?
The best way remains to wait for the 20-week ultrasound. If you guessed correctly with one of the two theories above, it could of course just be a coincidence.
