Gisele Bündchen Shares First Look at Child with Joaquim Valente

Gisele Bündchen's got one more reason to celebrate Mother's Day ... and, she couldn't help but share a snap of the kid -- giving fans a first look at her son with Joaquim Valente!

The model shared a pic of the kid's back ... decked out in a white sweater with "I ♥️ Mom" written across the back of it. The boy's holding tight to Gisele -- face over her right shoulder and away from the camera.

Another pic shows Gisele, all of her kids and Valente embracing ... with a heart strategically placed over her newborn's face to obscure his features.

The two pics are part of a larger Mother's Day Post ... in which Gisele uses her caption to tell fans she's been busy living life in recent months -- though she admits she's also keeping many of her recent developments to herself.

Gisele says she misses her mother quite a bit on the holiday ... but adds her heart is full -- 'cause being a mom is a wonderful gift that constantly teaches and fills her with gratitude.

She finishes off her caption by writing, "To all the mothers out there, your love shapes the world in ways words can’t describe. I see you, I honor you. Happy mother’s day! Sending so much love your way! ❤️"

As you know ... Gisele gave birth to her third child in February -- a boy named River.

She's kept a pretty low-profile since giving birth ... spending a ton of time with family. When she has stepped out -- like to hang with pals Karlie Kloss and Ivanka Trump -- River hasn't really been with her or she's hidden him well.