The best part of going to your high school reunion is spending time with pals from your past -- but a brand-new person in Kristin Cavallari's life kept her from attending her “Laguna Beach” 10-year gathering.

The shoe designer just gave birth to her third child -- baby girl Saylor James -- and this understandably meant she had to sit out this milestone event. But the MTV star -- who documented her years as a junior and senior student on the beloved SoCal based program -- wasn't totally MIA during the holiday weekend and gave her erstwhile class members a shout-out.

"Really sad about missing my 10 year high school reunion last night...so many people I wanted to see...but at least I have a good excuse," she added, along with a beautiful Instagram snapshot above with a first special glimpse of her mini-me. That's the most adorable/best/coolest excuse you could possibly have!

Even though K-Cav couldn't make it, fellow "Laguna" alum Jessica Smith Evans revisted that formidable time in her life and shared a photograph from the big night:

10 year reunion whaaaaat pic.twitter.com/X1WX2RPbrg

— Jessica Smith Evans (@TheJessicaEvans) November 30, 2015

Did you predict that Kristin would be a fashionista mom of three by now way back in her "LB" days? Let us know in the comments, and for a fun rewind, relive the LBHS Class of 2005's graduation day below: