Twin Birth Rate Hits a Record High in the United States

From right, Dante Cicerone, 15, and his twin brother, Georgie, are dressed up as Donald Trump at a rally in Las Vegas on December 14. Mike Blake/Reuters

You're not seeing double—there are just a few more twins around than usual. That's according to the annual Centers for Disease Control and Prevention's (CDC) National Vital Statistics Report, which found that in 2014 the twin birth rate hit an all-time high of 33.9 twins per 1,000 births.

Though it's a record, the rate is up only .2 from 2013, when it was 33.7 twins per 1,000 births. But the trend over the past few decades is dramatic: "The twinning rate rose 76 percent from 1980 to 2009," the report said.

According to the report, this national high is linked to increased access to improved fertility therapies, such as ovulation-inducing drugs, and assisted reproductive techniques, such as in-vitro fertilization, as well as the "older maternal age at childbearing" trend. Conceiving twins is more common with in-vitro fertilization because the doctor implants more than one embryo in the process. With multiple embryos, the chances of pregnancy increase—and so do the chances of having twins.

A Newsweek investigation in November 2014 found that twins conceived through in-vitro fertilization were more likely to be born early than single babies. The new report reiterated this point: "Infants born in twin and triplet deliveries are at a higher risk of adverse birth outcomes compared with singletons. In 2014, similar to earlier years, more than one of every two twins and more than nine of every ten triplets were born preterm or low birthweight."

Among non-Hispanic white women and Hispanic women, the twinning rate was nearly consistent over the past two years, though it was up 4 percent among non-Hispanic black women.

Although twin rates went up from 2013 to 2014, triplet (and more) births were down 5 percent, to 113.5 per 100,000 births.

Across the country, there were 3,988,076 registered births last year, about 50,000 more than in 2013. While the majority of these babies were first or second children for a mother, 21,589 were the eighth (or over) child.

While the twin rates were the focus of the report, the CDC also noted the teenage birth rate is down 9 percent from 2013, to 24.2 births per 1,000 women between the ages of 15 and 19. The average age of a mother having her first child was 26.3 last year, up from 26 in 2013.