The relationship between the time of conception and the birth of a boy or girl

　　female Conception time longevity boy The greater the chance that a woman will go from preparing to have a child to becoming pregnant fetus The longer it takes, the greater the chance of giving birth to a boy. This may be related to the fact that people who carry sex chromosomes sperm related to faster movement.

　　On average, for every 105 boys born, only 100 girls are born. One view is that this may be related to the chromosomes in sperm, because it determines male The y sex chromosome carries less DNA than the x chromosome, which determines a woman's gender. This allows sperm carrying the y sex chromosome to swim faster in a woman's cervical mucus.

　　Luke Smits from Maastricht University in the Netherlands believes that when the cervical mucus is extremely sticky, such women may need a longer time and multiple attempts to conceive. The advantage of sperm carrying the "lightweight" Y chromosome is more obvious at this time, and the chance of giving birth to a boy is therefore higher.

　　To test this theory, Smits surveyed 5,283 women in their 30s. Of the 498 women who took more than a year to conceive naturally, 56% gave birth to a boy. Among women who became pregnant within 1 year, 51% gave birth to a boy. Smits calculated that for every extra year it takes to conceive naturally, the chance of giving birth to a boy will increase by 4%.