14 DAY TRIAL // According to a new study, the longer a woman takes to get pregnant, the more chance there is of having a boy.
Researchers at the Maastricht University, the Netherlands, analyzed data for 5,283 women who gave birth to single babies between July 2001 and July 2003.
They found that the 498 women who took longer than 12 months to conceive had a 58 percent chance of having a baby boy, compared to the 51 percent for women who took less time to get pregnant.
For couples who conceive naturally, each additional year of trying to get pregnant is associated with a nearly 4 percent greater expected probability of having a baby boy, the study authors calculated. This was true even after the researchers adjusted for factors such as age, smoking status, alcohol use and menstrual cycle variability.
These findings support the idea that, in viscous fluids, sperms bearing the Y (male) chromosome swim faster than those bearing the X (female) chromosome. Women whose cervical mucus is relatively viscous would not only have more difficulties conceiving naturally, but also have a higher probability of male offspring if they do get pregnant.
The study found no relation between a baby's gender and length of time getting pregnant among couples who had medical help in conceiving.
Furthermore, the findings may explain why, throughout the world, more boys than girls are born (105 boys to 100 girls in most countries), despite the fact that human semen holds equal amounts of X bearing and Y bearing sperms.
There are some researchers who do not agree with this theory, Professor James Walker telling BBC that there are other factors, such as the vaginal fluids' pH and age, which dictate whether a male or female sperm were successful in fertilizing an egg.