A little over 1% of babies born in the U.S. in 2020 fell under the category of very low birthweight, meaning they weighed less than 1,500 grams at birth or 3 pounds, 4 ounces. And considering that the Centers for Disease Control and Prevention says more than 3.5 million babies were born that year, almost 48,500 were considered to be at very low birthweight.