Veah Netherton is celebrating another pregnancy milestone ... because TMZ has learned she's having a baby boy.

TMZ obtained never-before-seen photos from the "90 Day Fiancé" fan favorite's gender reveal.

The celebration went down May 30 in the backyard of her Florida home, where they sprayed a blue substance in the air ... signifying a son on the way with husband David Chairez.

We're told Veah has an October due date.

The baby news isn't the only big moment in Veah's life ... she's also returning to TV this Sunday on "90 Day Diaries."

The episode -- "Dear Diary, I'm Ready to Start Over" -- documents a pivotal chapter in Veah's life following her rocky relationship with Sunny Mahdi ... including David's surprise marriage proposal before the couple began their journey to parenthood.

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Veah revealed in May that she and David were expecting their first child together. She admitted the pregnancy came as a shock, but said they couldn't be more excited to become parents.

Congrats!!!