Kate Upton Announces She's Pregnant

9:30 AM PT -- Justin just posted, "You're going to be the most amazing Mom!! I can't wait to start this new journey with you! You're the most thoughtful, loving, caring, and strong woman I've ever met! I'm so proud that our little one is going to be raised in this world by a woman like you! I love you so much."

Kate Upton is catching what seems like the wave these days ... she's pregnant!!!

Kate just announced she's having a baby ... posting this pic Saturday from Miami. We've learned she's there for Sports Illustrated's Swimsuit Model Search during Miami Swim Week ... so pregnancy's not stopping her from working it.

Kate married Houston Astros pitcher Justin Verlander last November. They dated for 5 years. As you know, they got hitched just days after the Astros beat the Los Angeles Dodgers to win the World Series.

Kate captioned the pic, "#PregnantinMiami @justinverlander."

Unclear how far along she is ... but one thing's for sure -- Kate looks great!