The New York Times reports a substantial increase in age of dads with newborns.
Researchers at Stanford University reviewed data on 168,867,480 live births from 1972 to 2015, making statistical adjustments for missing paternal records. The average age of the father of a newborn in the United States, the investigators found, has risen to 30.9 from 27.4 in 1972.
The Times also reports in the same article at the oldest fathers live in the Northeast and youngest in the South.
While the average is near 31 years for dads of newborns, there are a substantial number of dads having kids at older ages. There are disadvantages which you can read in this article on the pitfalls for men of having babies after age 50.
The science is unsettled however on health risks for babies of older men. Some experts point to a possible link between aging sperm and birth defects, autism and even schizophrenia. More recently, this has been refuted by data suggesting these inherited traits may be more due to the higher tendency of these health issues among men who choose to have babies late in life.