Kindergarten enrolment in New Brunswick has increased in each of the last four years. (CBC)

The number of students attending New Brunswick's schools dropped below 100,000 for the first time since the 1940s in the school year that wrapped up Friday.

But hidden in the statistics is a mini baby boom that school planners didn't expect.

For the fourth year in a row, enrolment in kindergarten increased.

University of New Brunswick demography professor Michael Haan says the increase in kindergarten enrolment is no accident and tied to the children of baby boomers having their own families.

"These are the grandchildren of baby boomers," said Haan. "Baby boomers are well known. The baby echo is well known.

"This is what demographers refer to as the echo of the echo."

The baby boom generation includes those born between 1947 and 1966.

Haan says the children of post Second World War baby boomers began having their own children about 10 years ago. It's those grandchildren of the baby boomers who are now flooding the early grades of the school system, said Haan.

In 2013-14, 7,449 children entered kindergarten in New Brunswick. That's 450 more than four years ago and 1,000 more than school planners predicted there would be in studies published a decade ago..

Haan says the mini boom will likely continue for a decade.