There is no way of knowing if babies will be bald or hairy until they are born. This detail is a feature that is part of each person’s formation. It is as unlikely to figure out as it is to know if a baby will be tall or short. The fact is not related to the mother’s health or any pregnancy symptoms, nor does it have anything to do with the baby’s sex.
The reason why a baby is born hairy or bald
It has to do with genetics. The result of each person’s genetic sequence is affected by the combination of genes from both parents and four grandparents. This is why there is so much variation on the birth of siblings. Hair color and type - curly or straight, thin or thick - will vary depending if the baby will look more like the mother or the father’s family.
Hair is related to scalp protection and it is only necessary after birth. However, some children stay bald during the entire first year of their lives. It can take up to two years for hair to grow on babies. Cases in which the hair does not grow are very rare, but it can be a hair bulb deficiency known as alopecia.
In theory, hair is used for protection. It is unnecessary inside the uterus because, there, the baby does not get cold. Its interior temperature is constant. However, the myth that a hairy baby gives the mom heartburn is not true.
At the time of birth, what happens is that the younger or more premature the newborn is, the more peach fuzz they’ll have. Usually at 40 weeks old, the baby’s skin is more “flaky” because their development cycle is already over. The same happens to the scalp.