The number of twins that are born in the United States hit an all-time high in 2014 based on a report that was released by the nation's Centers for Disease Control and Prevention (CDC), but the number of other multiples is at the lowest figures in two decades. About 135,000 of the almost 4 million babies born last year in the US were twins, which is about 3.4 percent.
The CDC's National Center for Health Statistics released the report. Almost 34 twins were born for each 1,000 births during last year, according to CNN.
Twin birth rates increased among black women by 4 percent from 2013 to 2014. However, the rates were unchanged among white and Latino women.
The higher rates of twins are due to various factors. One is that more women are becoming mothers during their 30s, which boosts the chance of them having twins instead of one baby, according to 6-ABC.
Meanwhile, doctors have also been implanting fewer embryos through in vitro fertilization than during the past. The reason is that they can result in health risks.
However, experts point out that the number of births involving triplets or more newborns has dropped 40 percent since the figures peaked. That happened in 1998
The overall US birth rate in 2014 was also the highest since the year 2007. It was almost 63 births for every 1,000 women, and the first time it has risen between two years since the year 2007.
Since 2013, there was also a steep drop in the birth rate among teen mothers between the ages of 16 to 19. The figure plummeted 9 percent.