Price often dictates which fertility treatment couples receive

For example, physicians can control how many children a pregnancy produces through the use of in-vitro fertilization, or IVF.

"You see those higher-order (multiple births) – the ones that are more than twins – often in the group that doesn't do IVF," said Dr. Susannah Copland, of the Duke Fertility Clinic.

The cost of an average IVF treatment is about $13,000, and most insurance plans in North Carolina don't cover it. The least expensive treatment, which uses pills to boost fertility, starts at less than $1,000.

"We don't actually get a demand from employers in the marketplace to provide that coverage. It's quite expensive," said Dr. Genie Komives, senior medical director and vice president at Blue Cross Blue Shield of North Carolina.

Fourteen states require insurance companies to provide coverage for fertility treatments. North Carolina doesn't have such a mandate, but Komives said Blue Cross, the state's largest insurer, does offer some coverage.

"We stop short of artificial insemination and what they call artificial reproductive technology," she said.

That technology includes IVF.

Some experts argue that covering IVF could be less expensive for insurance companies in the long run by reducing the cost of caring for multiple babies, which often require longer hospital stays.

Copland said the decision about which type of treatment to seek often comes down to price. The expense sometimes means the people who are least likely to afford having two, three or more babies could be the most likely to have them, she said.

"I wish that more of my patients had the ability to choose (a treatment) on a level playing field," she said.

Kate Gosselin, one of the stars of the reality television show "Jon and Kate Plus 8," used a fertility treatment involving shots, which costs about $3,000. She and her husband wanted to have one more child after having twins, but they wound up with sextuplets.

Meanwhile, Wendy Fox and her husband spent almost $30,000 on three rounds of IVF before finally having twin girls two years ago.

"You do what you have to do to have children," Fox said. "It's been wonderful and fulfilling in a way that you would never know it could be unless you were a mom."