Baby boom is a term that is heard quite frequently to describe a generation of Americans. Do you know where it came from? Decades ago from the mid-1940s through the 1950s, lots of couples married and had babies. While this is nothing unusual, the rate of births was so high that the children born then were said to be part of a baby boom. Between 1946 and 1951, a record 22 million children were born in the United States. World War II played a big part in the baby boom.