For hundreds of years, Native Americans in the southwestern United States had a prolonged baby boom — which would average out to each woman giving birth to more than six children, a new study finds. That baby streak, however, ended a little before the Spanish colonized the Americas.

"Birthrates were as high, or even higher, than anything we know in the world today," said study co-author Tim Kohler, an archaeologist and anthropologist at Washington State University.

The precolonial baby boom was likely fueled by Native Americans in the region switching from a nomadic, hunter-gathering lifestyle to a settled farming way of life, Kohler said.