Red or black? Heads or tails? Boy or girl? When it comes to determining a baby's gender, many parents accept 50-50 odds. But what if you could stack the deck?
The Odds
Biologically speaking, baby's gender is determined by the father's chromosomal contribution. Should a sperm cell carrying a Y chromosome penetrate the egg (always an X), you'll be wrapping your XY newborn in blue. If dad contributes an X chromosome, princess paraphernalia is likely in your XX baby’s future.
So can you do anything to choose your baby’s gender? While the probability of having a girl or boy is 50-50 in a fair toss, some parents are biologically predisposed toward producing one sex or the other. In Europe and North America, boys outnumber girls 105 to 100, making the probability of having a boy 51.2 percent. It seems as if nature, or environment, has already stacked the odds. So why not you?
What Dad Can Do
People have offered plenty of notions about how you can increase your chances of conceiving a boy or girl. One theory, for example, dictates that fathers aiming for girl babies should wear tighty-whities, which raises body temperature in the testicles.
Since sperm carrying the female sex chromosome are thought to be heartier, they are more likely to survive those higher temperatures. Conversely, the argument goes, men should wear boxer shorts if they want a house filled with boys.
Timing Is Everything
The timing of conception might also make a difference. Following the theory that X chromosome sperm are hardier, couples who want a girl should have sex earlier in the woman's cycle, so that the Y-bearing sperm will die off earlier, leaving the X sperm to fertilize the egg during ovulation. Couples who are hoping for a boy should try to conceive just before ovulation, since sperm bearing the male chromosome swim faster.
Age and Baby's Gender
Other factors may also have a role. Older fathers are said to be more likely to conceive girls, as are families where both parents smoke cigarettes (not that we’re recommending that, even if you’re determined to have girl babies).
Chinese Birth Calendar
And then there’s always the Chinese birth calendar, a 700-year-old chart that claims to predict gender based on the mother's age at conception and the month in which the baby is conceived. Though the chart isn't backed by science, lots of parents swear by its accuracy.
One final, important note. Your best chances for conceiving are always within 36 to 48 hours before ovulation. By waiting or trying out tricky timing techniques to end up with one gender or the other, you may lower your likelihood of success in any given cycle.
When the time comes to meet your new baby, you’ll probably care less about gender than about counting all those fingers and toes, and having a healthy little one in your arms!