The number of babies born in the U.S. fell to a 30-year low last year.
According to a provisional report from the Centers for Disease Control and Prevention, there were about 3.85 million births in the U.S. in 2017.
That's down 2 percent from 2016 and the lowest number recorded since 1978.
Why? Experts aren't exactly sure.
But the drop could be the result of more women waiting longer to have children. The CDC's report found the birth rate decreased for women between the ages of 15 and 39, but increased for women aged 40 to 44.
The report showed teen pregnancy rates are also on the decline.
The total fertility rate in the U.S. in 2017 was once again below the level at which a generation can replace itself.
But, as The New York Times notes, lower birth numbers haven't led to a lower population in the past because they've been offset by immigration.
