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."