Choosing the Sex of Your Child

Several options are available for choosing the sex of your child, but none are guaranteed.

Medically Reviewed by Brunilda Nazario, MD
5 min read

Besides slipping the stork some extra cash, would-be parents have a number of options for choosing the sex of their child. The methods range from the natural (such as using particular positions during intercourse) to the high-tech (such as sorting sperm).

Couples have a 50/50 chance of conceiving a boy or a girl through plain old-fashioned intercourse. Yet there are some people who might want to stack the odds in their favor, either for cultural reasons, for dreams of raising a son or a daughter, or to balance out their families. Others do it to prevent their offspring from inheriting sex-linked genetic diseases.

Whatever the reason, health experts worry that some parents will place unrealistic hopes on a sex-determination technique and become disappointed whether or not they succeed. The method could either fail to produce a baby of the desired sex, or the right-gendered kid could grow up with traits that contradict with parental expectations. In this case, ethicists worry about the welfare of the child.

In addition, no preconception approach is foolproof, according to an ethics committee report in the May 2001 issue of Fertility and Sterility. Some popular strategies reportedly even fall under the category of foolery.

Of course, this list may not necessarily include your great grandmother's "tried and true" formula for choosing the baby's sex. Some doctors just chuckle at such schemes and say that as long as the advice doesn't hurt mom or baby, then there may be no harm in trying.

The Shettles method is arguably the most well-known natural strategy for choosing the sex of your child. Developed three decades ago by Landrum B. Shettles, MD, PhD, the plan involves timing intercourse to a woman's cycle and assuming certain sexual positions.

In his book How to Choose the Sex of Your Baby, Shettles explains that the male (Y) sperm is smaller, faster, and more short-lived than the female (X) sperm. Because of this, it is better for boy-desiring couples to have sex closest to the time when a woman's egg is released (ovulation). This way, the speedy male sperm could get to the egg sooner than the female one.

The Y chromosome apparently also enjoys an advantage over its counterpart when the sperm is discharged as close as possible to the opening of the cervix. This is achieved through rear entry intercourse (man enters woman from behind).

Parents desiring a girl, on the other hand, are encouraged to have sex in the missionary position (face to face, man on top) about two to four days before ovulation so that by the time the egg comes, only the heartier, more resilient X sperm will remain in the woman's reproductive tract.

The Shettles method has reportedly been effective at least 75% of the time, with the rate slightly lower for girls than for boys. Pat Buie, a registered nurse from Canada, incorporated Shettles' method into her sex selection plan -- described in her book Choose the Sex of Your Baby Naturally -- and claims to have a 95% success rate.

Many fertility experts question the value of natural sex selection strategies such as the Shettles method.

"There's no real evidence to show that they work," says Sandra Ann Carson, MD, president of the American Society for Reproductive Medicine, noting that such techniques are as effective as random sex in producing a baby of the preferred sex.

J. Martin Young, MD, a pediatrician in private practice in Amarillo, Texas, reviewed medical literature on sex determination and found that the Shettles method fared worse than random sex, with a 39% success rate in choosing the sex of your child.

Shettles' ideas seem to make sense, but they're a little too simplistic and not based on scientific research, says Young, who authored two books on the subject. In How to Have a Boy and How to Have a Girl, he describes a strategy that opposes Shettles'.

"If you would like to have a female, you would schedule intercourse to be as close to the time of ovulation as possible," says Young. "If you would like to have a male child, you would have intercourse a number of days before to try to increase the probability."

The success rate for this strategy of choosing the sex of your child, says Young, can be as high as two chances in three (about 67%), if done properly.

The odds of choosing the sex of your child may be even better with the help of technology. According to the fertility experts contacted by WebMD, MicroSort -- a method that involves separating the male sperm from the female -- is the current gold standard.

"The only effective method that I feel would be useful for sex selection is the MicroSort technique," says William Gibbons, MD, director of the EVMS Jones Institute for Reproductive Medicine.

Carson agrees. "I think sperm sorting is probably the most viable method that we have right now, but it's probably most effective when it's used in combination with in vitro fertilization."

MicroSort, which is licensed by the Genetics and IVF Institute in Fairfax, Va., is undergoing an FDA clinical trial. The technique involves separating X- and Y-bearing sperm by using laser light, dye, and a machine called a flow cytometer. Once the sperm are divided, the specimens are inserted back into the woman through artificial means, such as in vitro fertilization.

A news release issued in October 2002 from the Genetics and IVF Institute reports that MicroSort has a 91% success rate among couples wanting girls, and a 73% rate for those wanting boys.

MicroSort, however, isn't the only high-tech method for choosing the sex of your child. Other more controversial strategies include preimplantation genetic diagnosis (PGD), and chorionic villus sampling (CVS) -- both of which are used to detect medical illnesses but can also be used to distinguish sex.

To determine sex, PGD involves examining an embryo taken from the uterus and replacing only the embryo of the desired sex. In CVS, chromosomes of the fetus are analyzed in early pregnancy. There are reports that some people who find out they have an unwanted gender through this technique end up asking for an abortion.

The American Society for Reproductive Medicine recommends neither PGD nor CVS as a sex selection method for couples looking to balance the gender ratio in their families.

Published May 5, 2003.