The number of twins has surged in the past 30 years, according to a new government study. The twin birth rate went from 189 out of 10,000 births (or 1 out of 53) in 1980 to 333 out of 10,000 births (or 1 out of 30) in 2009—a spike of 76%, reports MSNBC's Vitals blog. What's behind it? Experts point to an increased use of infertility treatments and to the growing number of women giving birth at a later age.
The study's lead author says it's not necessarily good news: “It’s really important to note that outcome for twins is much less positive than for singleton pregnancies."