Can You Choose Baby's Sex?

Many parents swear by at-home methods of gender selection. But can you really sway the odds?

Does This Really Work?

Ellen Durston, a newspaper reporter in Chicago, always wanted her first child to be female. "Firstborn girls are more ambitious and confident than girls with an older sibling," contends Durston, 30, a secondborn. So when Durston and her husband decided to conceive, she began researching methods that would improve their odds of having a girl.

Durston came across a technique pioneered 30 years ago by obstetrics researcher Landrum Shettles, M.D., Ph.D. After following his advice, she became pregnant with Zoe, now 2. Would Zoe have been Zachary if the couple had left it to chance? Quite possibly, by Durston's reckoning: "I'm convinced that the Shettles method is why I had a girl."

Dueling Theories

Gender preference is as old as conception itself, and so are theories about how to make it materialize-from ancient Talmudic advice to orient the marital bed north-south for a boy to Germanic folklore that suggests placing a wooden spoon under the bed ensures a girl. Even in this scientific age, theories-and couples eager to test them-abound.

Of them all, the Shettles method has the greatest following. Its premise is relatively simple: The Y-chromosome-carrying sperm (the one that results in a boy if it fertilizes an egg) is smaller, lighter, and faster-moving than sperm carrying the X (or female) chromosome. Conversely, the slower-swimming Xs are more resilient. According to Shettles advocate Pat Buie, author of Choose the Sex of Your Baby Naturally, this means that male sperm cells move through the woman's reproductive tract faster than female cells. In addition, an X sperm can withstand a more acidic environment, while a Y is more likely to survive in an alkaline environment. Accordingly, Buie counsels couples who prefer a boy to time intercourse to coincide with ovulation. This way, the swift Y sperm can beat the competition to the just-ripe egg (if the Y has to wait two days for an egg to be released, it will die). She also recommends rear-entry lovemaking (deeper penetration deposits the sperm closer to the cervix, thus avoiding the acidic vagina) and female orgasm, which increases cervical alkalinity. To conceive a girl, the Shettles method advises having sex no later than two days before ovulation (so that only the hardy X sperm will be alive when the egg ripens); using the missionary position (so that sperm penetrate less deeply and thus are exposed longer to the vagina's acidic secretions); and delaying female orgasm until after the man ejaculates.

Buie, a former nurse, maintains that the Shettles method has a 75 percent success rate overall and a 95 percent rate among her clients. There is little research, however, to back up her assertions. In fact, several fertility journals in the 1980s and '90s suggested that, if anything, girls are more likely when intercourse occurs at ovulation, and boys if it takes place before or after.

Enter J. Martin Young, M.D., author of How to Have a Boy and How to Have a Girl. The flaws in Dr. Shettles's theory, says the Texas pediatrician, stem from its being based on artificial insemination. For couples conceiving naturally, Dr. Young prescribes the opposite course.

Among his satisfied customers are Julie and Wolf Puckett. Five years ago, the Amarillo, Texas, couple consulted Dr. Young's book for help in conceiving a boy. Julie and Wolf charted Julie's temperature to determine ovulation, and they had intercourse several days before she was set to ovulate. Afterward, Julie raised her hips with a pillow, as Dr. Young advises. Whether by design or by chance, the system worked. The Pucketts' son, Hunter, is now 4.

The Ultimate Gamble

If these conflicting theories sound confusing, they are. Furthermore, there's no proof that they work any better than the wooden-spoon method. One of the few reputable studies on the subject, published in The New England Journal of Medicine, found no correlation between gender and the timing of intercourse. "These theories simply don't stand up to scientific scrutiny," says Joshua A. Copel, M.D., a professor at Yale University School of Medicine.

There are circumstances-a gender-linked disease, for instance-when sex preselection makes medical sense, in which case parents may want to seek high-tech interventions. (See "Selective Services," below.)

Otherwise, the do-it-yourself methods are best regarded as harmless fun-fine to try, as long as would-be parents are open to a child of either sex. (Those who aren't might well question the wisdom of becoming parents at all.) "In conception, gender is always a gamble," Dr. Copel observes, "and you have to be willing to accept whatever you get."

    Selective Services

    For couples with a family history of certain diseases, gender selection is more an imperative than a preference. About 500 serious diseases, including hemophilia and Duchenne muscular dystrophy, develop only in males (though females can be carriers). Increasingly, experts say, couples at risk are using technology to avoid having a boy.

    One method, called MicroSort and available at the Genetics and IVF Institute in Fairfax, Virginia, separates the X and Y sperm, then uses the desired kind to fertilize the egg either in vitro or through artificial insemination. The institute boasts a 91 percent success rate with girls and a 74 percent rate with boys. MicroSort, currently in FDA clinical trials, offers its services to married couples interested in family balancing and to families with genetic diseases. Fees start at about $2,550.

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      Copyright © 2003 Alice Lesch Kelly. Reprinted with permission from the April 2003 issue of Parents magazine.

      All content here, including advice from doctors and other health professionals, should be considered as opinion only. Always seek the direct advice of your own doctor in connection with any questions or issues you may have regarding your own health or the health of others.