Men in the U.S. are becoming fathers later in life, according to researchers at Stanford University who studied data from nearly 170 million live births from 1972 to 2015, per The New York Times. The average age of a father of a newborn baby in the U.S. has risen to 30.9 years from 27.4 years in 1972, the study authors reported in the journal Human Reproduction.

• The oldest fathers live in the Northeast, while the youngest live in the South.
• The average age of fathers with college degrees is 33.3 years old, while the average of those with only a high school diploma is 29.2.
• Asian fathers were the oldest on average by ethnicity, and black and Hispanic fathers the youngest.

One concern: Research has shown that fathers who conceive at a later age in life have children who are more susceptible to miscarriages, birth defects, cancers, schizophrenia, and autism. Some scientists have also suggested that older age can cause random genetic mutations during sperm production, which can lead to disease and other genetic disorders.