Credit: Steve Granitz/; Triton/Flynet; FameFlynet Pictures

On Wednesday, Us Weekly broke the news that Reese Witherspoon is pregnant with her and hubby Jim Toth's first child together! And on Thursday, the Oscar winner celebrates another milestone: Her 36th birthday.

"Reese is right around 12 weeks," one source explains.

So in honor of the expecting star, who is already mom to Ava, 11, and Deacon, 8, Us looks back on her body evolution.

Going all the way back to when she was just 19 up through present day, see how the 5-foot-2 actress' body has bounced back through both pregnancies and her divorce from her husband of seven years, Ryan Phillippe, in 2007.

Plus, look back at memorable moments like when she first debuted her giant tummy tattoo!

Tell Us: Which Reese moment has been your overall fave?