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Knicks' Isaiah Hartenstein Expecting Baby W/ Model Wife ... Announce Pregnancy W/ Assist From 'The Garden'

Isaiah Hartenstein and his model wife Kourtney Kellar have a little bundle of joy on the way ... and the soon-to-be momma used her Knicks center hubby's office -- Madison Square Garden -- to make the announcement!

Kellar posted video from the floor at MSG, showing an ultrasound image and number 55 onesie (Hartenstein's #) draped over one of the courtside seats ... while Stevie Wonder's Signed, Sealed, Delivered played in the background. KK captioned the IG post, "Baby boy due June 2024 💙"

She also wrote "7 FOOT BABY LOADING..."

(Here's hoping the baby does most of his growing after birth.)

Hartenstein and Kellar first met back in 2019, when the young NBA hooper slid into the ring girl's DMs. Isaiah complimented her smile ... which Kourt thought was sweet.

After a few FaceTime dates the two decided to meet up in Houston (her future hubby was playing for the Rockets at the time).

It was smooth sailing from there ... and after about 3 years, the couple announced their engagement on a beach in Malibu!

Isaiah and Kourtney tied the knot in August 2023.

While Hartenstein's known for his game on the court (he's having a nice year for the NYK, averaging over 8 rebounds a game), Kourtney’s a star in her own right.

In fact, back in 2021, she went viral working as a ring girl for the Jake Paul vs. Tyron Woodley fight, helping her amass over 715k followers on IG alone.

Congrats to the growing fam!

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