Are the chances of getting a boy or girl equal?

Question

When a woman is pregnant, is the chance of having a girl or boy equal 50/50? Or are there like some biology stuff determining the odds?

In: Biology

Answer 1

It very slightly favors boys as least when it comes to live births. The reasoning behind this is unclear. It’s possible this is an evolutionary trait because Paleolithic males died more often hunting or in warfare so the slightly higher birth rate compensated. Another theory is that there is something inherently different about male and female sperm causing this. The only known different is that the male has an XY chromosome pair instead of an XX pair. The Y chromosome is basically an X chromosome with one section missing so there’s one theory that this sperm is carrying slightly less weight and is therefore slightly lighter and faster when it swims.