The study, published online ahead of the print edition of the journal Pediatrics, said maternal spanking at age 5, even at low levels, was associated with higher levels of child externalizing behavior at age 9, but a father's high-frequency spanking at age 5 was associated with lower child receptive vocabulary scores at age 9.
An individual's receptive vocabulary includes all of the words that one recognizes and understands upon hearing or reading them.
The study also found 57 percent of the U.S. mothers and 40 percent of the U.S. fathers engaged in spanking when their children were age 3, and 52 percent of mothers and 33 percent of fathers engaged in spanking at age 5.
Notable deaths of 2014 [PHOTOS]
Paralyzed man walks after cell transplant