About one out of five couples who come to HRC Fertility, a network of fertility clinics in Southern California, doesn’t need help getting pregnant.

Instead, they come for what is called family balancing, or nonmedical sex selection.

“They usually have one, two or three children of one gender” and want their next child to be of the other sex, said Daniel Potter, medical director of HRC Fertility, which includes nine clinics.

Women who want to select their baby’s sex undergo the costly and cumbersome process of in vitro fertilization (IVF) to create embryos that are also genetically tested before being implanted. Although the testing, broadly referred to as preimplantation genetic diagnosis, or PGD, is often used to test for genetic diseases, it can also identify the sex of the embryos. The IVF/PGD process can cost as much as $15,000 to $20,000 a cycle and isn’t covered by many insurance plans.

“The growth part of our practice at this point is in fact the segment of the population that technically doesn’t have fertility problems,” which includes same-sex couples and couples with genetic diseases, Dr. Potter said.

Nonmedical sex selection is a controversial practice legal in only a few countries, including the U.S. and Mexico. Medical organizations and fertility specialists are split on the issue. No agency tracks the numbers of procedures performed.

Family-balancing services are advertised prominently on many clinics’ websites. Some clinics, including HRC Fertility and Fertility Institutes, which has offices in Los Angeles, New York and Mexico City, say they are seeing growing demand for the services, particularly from foreign couples.

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