WHAT IT IS: This sex-selection technique, named after author Elizabeth Whelan, is centered around the timing of intercourse.
HOW IT WORKS: Unlike Dr. Shettles, Whelan claims that the best way to increase the odds of having a boy is to have sex four to six days before you ovulate and for a girl, to abstain from intercourse until two or three days before ovulation. Her advice is based in part on studies done by Rodrigo Guerrero V., M.D., a physician studying at the Harvard School of Public Health in the late 1960s, who charted outcomes of couples who timed their conceptions.
SUCCESS RATE: Whelan claims her success rate is 68 percent for boys and 58 percent for girls. Like Dr. Shettles' method, Whelan's isn't universally accepted by doctors of reproductive medicine.
COST: $5.99 -- the price of her book, Boy or Girl?
WHO IS ELIGIBLE: Any woman with a calendar, a thermometer to pinpoint ovulation, and a regular menstrual cycle.
RESOURCES: The book.
Linda Weber is the managing editor of Mother Jones magazine.