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 the late obstetrics researcher Landrum Shettles, M.D., Ph.D, who wrote How to Choose the Sex of Your Baby. 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."
Jean and Robert Krak of McMurray, Pennsylvania had a similar experience. The proud parents of three boys, ages 7, 6, and 2, the couple "wanted a fourth child, and wondered if there was any way to slant the odds in favor of having a girl—to have the experience of raising a daughter," says Jean.
An obstetrician gave her instructions for timing fertilization, intercourse positions, and using a douche to increase her chances of having a girl. "He made no promises but said this technique had worked for others," says Jean. "We figured we'd try it, knowing that God still had the ultimate veto power." The family now includes their youngest, Angela Marie.
Gender preference is as old as conception itself, and so are theories about how to make it materialize—from ancient Talmudic advice that says if a wife's orgasm precedes her husband's, the baby will be a boy to Germanic folklore that suggests placing a wooden spoon under the bed ensures a girl. In the 13th century, a Chinese scientist created a chart that a woman could use to match her age to the month of the year when she was likely to conceive a boy or 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, some research has found that the Shettles Method may increase a couple's chances of having the opposite sex of the one they want. One study found that couples who followed his advice had only a 39 percent chance of conceiving the gender of their choice. That's less than the 50-percent chance they'd have if they let nature take its course.
"What Dr. Shettles proposed seems to make sense," says Masood Khatamee, M.D., an obstetrician-gynecologist at Mount Sinai Beth Israel in New York City. "But when put to the test, his methods haven't held up."
J. Martin Young, M.D., a private-practice pediatrician in Amarillo, Texas, and author of How to Have a Girl and How to Have a Boy, says the flaws in Dr. Shettles's theory stem from its being based on artificial insemination. For couples conceiving naturally, Dr. Young prescribes the opposite course. "My method is based on the fact that at least five studies, some of which tested Dr. Shettles's theory, have found that girls are usually conceived right at ovulation and that boys are conceived four to six days before and two days after ovulation," says Dr. Young.
His recommendations? Have sex within 24 hours of ovulation to increase your chances of conceiving a girl to about 55 to 60 percent; to increase your odds of conceiving a boy to about 60 to 65 percent, have sex four to six days preceding ovulation and then abstain. The woman should remain still for 20 minutes after intercourse to increase the survival of all sperm and the chance of fertilization. In addition, use a baking soda douche.
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. The Pucketts charted Julie's temperature to determine ovulation, then 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.
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.
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."
Yet 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.
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, separates the X and Y sperm, then uses the desired kind to fertilize the egg either in vitro or through artificial insemination. The Genetics and IVF Institute in Fairfax, Virginia, where it was developed, says the method boasts a 91 percent success rate with girls and a 74 percent rate with boys. However, after the FDA banned the use of sperm-sorting for sex selection in 2011, MicroSort is no longer available in the U.S. Instead, its labs are located in Mexico, Malaysia, North Cyprus, and Switzerland. The company offers its services to married couples interested in family balancing and to families with genetic diseases; fees start at upwards of $3,000.
This story is a composite of articles reprinted with permission from the Spring 2001 issue of Expecting magazine and the April 2003 issue of Parents magazine. It was updated in 2018.