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Cory Morse/The Grand Rapids Press via AP
Kateri Schwandt watches her new baby boy at Mercy Health Saint Mary's Campus in Grand Rapids, Mich., Thursday, May 14, 2015. Kateri, and her husband Jay Schwandt, now have 13 children, all boys.

ROCKFORD, Mich. — A Michigan couple who already had 12 sons kept the all-male streak alive with the birth of boy No. 13 on May 13.

Jay Schwandt told The Associated Press that his wife Kateri gave birth four days after her due date.

The couple had said in an earlier Associated Press interview that they were sticking to the tradition of not knowing the baby's sex ahead of time.

"Ok, so the boys know now!" Schwandt said in a post on Facebook announcing the birth. "It's a BOY! Now we need to choose a name! BLESSED beyond belief!"

Kateri Schwandt, 40, says she has a lot of experience with large families, as one of 14 children herself.

In that earlier AP interview, she said she finds motherhood to be "very rewarding."

"Your children are a little piece of you. Every day is Mother's Day," she said. "They will bring me flowers that they pick in the yard. Even if it's a dandelion, it's special because they were thinking of Mom."

Jay Schwandt told The Associated Press in a text message that the couple decided Friday, May 15, to name their newborn Francisco Matthew Schwandt.

The father said earlier it was a challenge for him and his wife, Kateri, to agree on a name.

The family lives in Rockford, north of Grand Rapids. They don't have any daughters.