Image copyright AP Image caption The first 12 Schwandt boys, pictured in 2013

A US couple who already have 12 sons but no daughters have welcomed a 13th boy into their household.

The latest member of the Schwandt family was born on Wednesday morning in Grand Rapids, Michigan.

In keeping with family tradition, Jay and Kateri Schwandt chose not to know the baby's sex before the birth.

"I was thinking, 'If this is a girl, I don't know what my reaction is going to be'," said Mr Schwandt, 40, just moments after his son was born.

The ages of their boys extend over more two decades, starting with Tyler, 22, followed by Zach, 19, Drew, 18, Brandon, 16, Tommy, 13, Vinnie, 12, Calvin, 10, Gabe, 8, Wesley, 6, Charlie, 5, Luke, 3, and 21-month-old Tucker.

"There's a lot of commotion, a lot of chaos, but there's also a lot of love," said Ms Schwandt.

The family is now trying to settle on yet another boy's name, and have been seeking a little help from their other sons.

But so far the boys still haven't agreed on a name.

Image copyright AP Image caption Kateri Schwandt with her youngest boy

Image copyright AP Image caption The 13th son

Kateri Schwandt, 40, comes from a family of 14 children.

She was the 13th child born in her family and she says that the significance of the 13th child being born on the 13th day of the month has not been lost on them.

The Schwandt family has been approached by several TV production companies with offers of their own reality show, according to the Grand Rapids Press newspaper.

Mother and son are both doing well and resting in hospital.

But are they likely to add a 14th boy to the family in the future?

"You never say never," said Mr Schwandt.

What are the chances?

1 in 8192 (two to the power of 13)

The odds of having a boy don't change, the more boys you have, says Peter Bowen-Simpkins, medical director at the London Women's Clinic: "The odds are just about 50-50. It's like tossing a coin."

Does having children of one sex affect chances of having more?