Timing of FertilizationDetermines a Baby’s Gender

When both the mother and father learn about the pregnancy, they naturally become curious about whether the baby will be a boy or a girl.
So let us look at how gender is determined.

Gender is decided by the sex chromosomes.
Humans have 46 chromosomes arranged in 23 pairs, and one pair of these is the sex chromosomes. Males have XY sex chromosomes, and females have XX. Male sperm carry either an X or a Y chromosome, while female eggs carry only an X chromosome.
At fertilization, if an egg is fertilized by an X-bearing sperm, the resulting embryo has XX chromosomes and becomes a girl because it does not contain the Y chromosome.
If the egg is fertilized by a Y-bearing sperm, the resulting embryo has XY chromosomes and becomes a boy, since it has the Y chromosome.
In short, the baby’s gender is determined by which sperm, X or Y, reaches and fertilizes the egg first.
Because all female eggs carry the X chromosome, it is the sperm that determines whether the baby will be male or female. If a sperm with a Y chromosome fertilizes the egg, the baby will be a boy.
During ejaculation, around 100 million to 500 million sperm are released. Only a few hundred manage to reach the egg, and just one will fertilize it, creating a new life.

When Can You Find Out a Baby’s Gender?The Most Important Thing Is a Healthy Birth

Although a baby’s gender is determined at the moment of fertilization, it can only be identified during the second trimester by ultrasound (sonogram) examination.
A boy’s gender can often be confirmed around weeks 14–15 of pregnancy, and a girl’s around weeks 17–18, though a clear determination is usually made around week 24.
However, depending on the baby’s position or the viewing angle, it can sometimes be difficult to see, so ultrasound predictions are not 100% accurate.

Knowing the baby’s gender early makes it easier to prepare clothes and baby supplies.
On the other hand, some parents prefer not to know until birth.
In that case, it is best to inform your obstetrician beforehand.
Many old sayings claim you can tell a baby’s gender by observing the pregnant mother, such as:

• ○ If the belly sticks out forward, it is a boy; if it spreads to the sides, it is a girl
• ○ If the mother’s face becomes sharper, it is a boy; if her features soften, it is a girl
• ○ Strong fetal movements mean a boy; gentle ones mean a girl
• ○ Mild morning sickness means a boy

However, none of these has any medical basis.
The shape of the belly is influenced by the mother’s body type, the baby’s size and position, and the amount of amniotic fluid. For example, tall mothers tend to have longer, narrower bellies, while shorter mothers’ bellies look rounder. When the baby’s back faces outward, the belly may appear pointed, while when the baby faces outward, it can look round.
Some fetuses are very active, and others are calmer.
But there is no connection between movement strength and sex.
So, judging gender by belly shape or fetal activity is not medically possible.
Although various methods of “gender selection” are discussed, none are 100% reliable.

What matters most is that the baby is born healthy. Whether it's a boy or a girl, it's precious to cherish this time as you look forward to the day you will meet your child.
The time spent imagining whether it is a boy or girl, discussing with your partner the future and what you will do together, is a truly joyful part of expecting a baby.