Can Diet Determine a Baby's Sex? Poppycock!

A new study suggests that skipping breakfast can give you a girl, but an expert questions the finding.


When a close friend of mine gave birth to a baby girl years ago (after having three boys), she gave all the credit for her baby's gender not to a roll of the dice but to a bestselling book she'd read called How to Choose the Sex of Your Baby. "It really worked!" she confided to me. She outlined the book's theories concerning the timing of sex a few days before ovulation, douching with water and vinegar, and standing on one's head after intercourse to improve the odds of "girl" sperm reaching the egg. OK, I made that last one up. But I'm dubious of gender selection methods and question the merits of a new study showing that skipping breakfast is more likely to yield girls. I'm surprised at how much the media are playing up these results in articles like this one and this one.

In the study, University of Exeter researchers found that British women who ate cereal every morning before they got pregnant had a somewhat higher intake of vitamins and minerals and consumed about 130 calories a day more on average than frequent breakfast skippers. The breakfast eaters were more likely to have boys than those who skipped breakfast and ate less. Both groups of women had similar body weights, which means those who conceived boy babies were probably more likely to be exercising and following an overall more healthful lifestyle. The researchers say evolution favors having boys during times of plenty and having girls during times of distress (i.e., when there's less food around).

"It's true boys are the weaker sex," says Alice Domar, an assistant professor of obstetrics, gynecology, and reproductive biology at Harvard Medical School and coauthor of Conquering Infertility. "Boy sperm more often die on the way to the egg; they're more likely to die in utero, and more likely to die when born premature." Still, she adds, "I can't accept the results of this study. It's just making a correlation between a woman's diet and the gender of her baby. There's no real proof." She's also worried that some women will hear about this study and decide to skip breakfast and skimp on nutrients in an effort to have a girl. Folate-fortified cereals, for example, are vital for preventing birth defects. "What a woman eats can have a profound impact on the health of her baby, whereas if you look at the data from this new study, it's virtually impossible for a woman to change the sex of her baby."

Websites promising to help women do this, however, are far too easy to find. A Google search of "gender selection" turned up 150,000 hits. At the top of the list, a site called In-Gender has a pretty comprehensive list of things you can try. The super-high-tech, superexpensive preimplantation genetic diagnosis (PGD) is virtually 100 percent accurate because it actually analyzes an embryo's sex chromosomes before doctors implant it into the uterus. Lower-tech methods are questionable in terms of how much they'll increase your odds. Some experts say having sex about two days before ovulation helps produce a girl and having sex on the actual day of ovulation helps produce a boy. Sperm with the female sex chromosome last longer in the reproductive tract, Domar explains, whereas sperm carrying the male sex chromosome die earlier but swim faster and are more plentiful.

Some websites, though, seem just plain wacky. I'd steer clear of the Dr. Jonas Method website, which says "if the planned day for conception falls within the period of monthly menstruation, the conception can also occur." Hmm. So I can get pregnant while menstruating? Ah, highly unlikely., with its free interactive ovulation calendar, seems promising—until you see the bizarre way in which it calculates days for having a boy versus a girl. There are two boy days and five girl days in July, the site says, but 14 boy days and zero girl days in August. Then there's the expensive sperm-sorting method called MicroSort that has yet to receive FDA approval even though it's been around for several years.

Domar, who has two girls, tells me she hates all these methods. With the exception of the high-tech methods, "your chances of changing the sex of your baby are very, very small," she asserts. "But what really bothers me is the obsession people have in choosing the sex of their children. Why can't they just focus on having a healthy baby?" Good point. Here's how to do just that.

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