CDC – The rate of twin births in the United States reached a record high in 2014, according to an annual report released Wednesday, December 23, 2015, by the Centers for Disease Control and Prevention’s National Center for Health Statistics.
For every 1,000 births in 2014, 33.9 twins were born, the report shows.
For white, black and Hispanic women, the twin birth rate has been climbing since 1980.
However, between 2013 and 2014, it only went up among black women by 4 percent, according to CNN. The rates did not change among white and Hispanic women.
However, it’s not entirely clear what caused the shift. Researchers believe that changes in reproductive technology may be responsible for certain changes over the years, including the use of in vitro fertilization
However, the report also revealed a decrease in the number of triplets and higher multiples over the past 20 years.
At this time, researchers believe the rise in twins may also have something to do with the fact that more women are giving birth later in life–a time in which the occurrence of twins is higher, health officials say.