A large study in Australia and New Zealand finds the odds of having a boy increase with invitro fertilization. That involves an egg being fertilized in a lab.
The research in the British Journal of Obstetrics and Gynecology looked at nearly 14,000 births. In the study the likelihood of an IVF birth resulting in a boy was between 53 and 56 percent, depending on how soon the fertilized egg was put back in the woman.
Researchers have no answer why this is so but they warn that their findings should not be exploited for sex selection.