(Thinkstock image)

For health insurers, the birth of triplets or higher-order multiples can lead to huge bills for handling a high-risk pregnancy, long hospital stays for premature babies, and follow-up care for “super twins” who emerge with chronic conditions.

Researchers from the federal Centers for Disease Control and Prevention and Brown University report in this week’s New England Journal of Medicine that fertility treatments seemed to cause only about 36 percent of U.S. twin births in 2011 but 77 percent of the super twin births.

Fertility treatments other than in vitro fertilization (IVF) — including use of fertility drugs and artificial insemination — led to about half of the twin births in 2011 but only about 40 percent of the super-twin births that year, the researchers reported.

The share of IVF-related super twin births as a percentage of all medically assisted conceptions has fallen sharply since 1998, but the share of super twin conceptions caused by all kinds of fertility treatments has fallen only slightly over that period.

Although the percentage of super twin births caused by fertility care has changed little, the risk that mothers will have super twins at all has decreased rapidly,  from a high of about 1.5 births per 1,000 live births that year to a little less than 1 per 1,000 live births in 2011.

IVF treatments can cause super twin pregnancies when doctors try to save money and reduce the need for future treatments by implanting three or more embryos at the same time.

Guidelines urging the use of fewer embryos were strengthened following the 2009 “Octomom” case, in which a California woman had octuplets after her doctor implanted 12 embryos through an IVF procedure.

But most cases of infertility are treated not with IVF but simpler measures such as drugs that make the ovaries produce eggs. The first step often is a pill, Clomid, to spur hormones that aid conception. If that doesn’t work, more powerful drugs can be given in shots, but those bring a much higher risk of multiple eggs being released.

Doctors are supposed to use ultrasound and blood tests to monitor how many eggs are being produced and advise couples against trying to conceive that month if there are too many, to minimize the risk of multiple births. But that monitoring often isn’t done, or done well, and couples eager for a baby may disregard the advice.

“It’s very easy to demonize this dumb doctor who didn’t do the right thing,” said Dr. Nanette Santoro, obstetrics chief at the University of Colorado in Denver. “That may not always be the case. Frustrated people who don’t get pregnant after a couple cycles will think more is better. It’s the American way.”

In the new study, the researchers examined trends over several decades and finds that the rate of triplet and higher-order births peaked in 1998 and has been declining since then.

Dr. Fady Sharara of the Virginia Center for Reproductive Medicine in Reston, Va., and an OB/GYN at George Washington University, said he urges couples to avoid multiple births, and to use one embryo at a time if they are doing IVF.

“There are medical, social, emotional and financial reasons to avoid having twins” or larger multiple births, he said.

See also: