Last year, 3,853,472 babies were born in the United States. Though 3.8 million-plus newborns might seem like a lot, the tally is actually a 30-year low and is down 2 percent from 2016, according to a new report by the National Center for Health Statistics, part of the Centers for Disease Control and Prevention. Overall, it reported about 60 births per every 1,000 women ages 15 to 44 years. (This is what is known as the general fertility rate.) The data revealed fewer teen births (down 7 percent) and, actually, fewer births among all age groups younger than 40. The birthrate was up, though, among women in their early 40s. The rate for births by Caesarean section rose to 32 percent, and rates increased as well for preterm births (up to nearly 10 percent) and babies born at a low birth weight (8.27 percent, highest in more than a decade). A long-term side effect of all this? A population shift that could create what’s called an aging society — when people older than 65 outnumber those younger than 15.