Can you guess what Hollywood superstar actress is expecting her third child? HINT: Her oldest daughter is 12 and youngest son is 8!

By: MARK RALSTON/Getty Images

It’s Reese Witherspoon!

The This Means War star, who turns 36 on Thursday, is expecting her third child (her first with husband Jim Toth), a source told Access on Wednesday. Reese and Jim, a CAA entertainment agent, tied the knot at the actress’ Ojai, Calif., ranch estate last March after announcing their engagement in December 2010. The Oscar winner is already mom to daughter Ava, 12 and son Deacon, 8 – her children with ex-husband Ryan Phillippe.