What was the precursor to the baby boom?

WWII was the precursor to the Baby Boom.

The term "Baby Boom" most often refers to the post–World War II Baby Boom (1946–1964) when the number of annual births exceeded 2 per 100 women (or approximately 1% of the total population size). There are an estimated 78.3 million Americans who were born during this period.

Idon’t know i’m doing this for points