Shaun Alexander just announced he and his wife are expecting their FOURTEENTH child!!

The ex-NFL superstar revealed the great news while on Kay Adams' "Up & Adams Show" on Thursday ... and check out the clip, he couldn't have been happier to share the update.

"We're just now starting to tell people," the former Seattle Seahawks tailback said with a big grin, "but No. 14 is in the belly."

Alexander and his partner previously had 10 daughters and three sons ... though he did not say what the sex is of the current bun in the oven.

In addition to the pregnancy, Shaun also got some good news regarding his Hall of Fame candidacy this week ... as it was announced he's one of 128 modern-era finalists for the Class of 2026.

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Alexander and Adams actually joked about his possible induction, quipping he's more deserving of the honor than Philip Rivers, who only has 10 children.

No word yet when the due date for the next Alexander is ... but if it's around the time the class is formally announced -- and Shaun gets in -- what a memorable day that would be for the ex-halfback.