"Whenever you're pregnant, you always call on your pregnant friends and compare notes," the 39-year-old Watts – who gave birth to son Alexander Pete last July – told PEOPLE Monday at a press conference to discuss her new role as the face of Angel, a fragrance by designer Thierry Mugler. "It's what happens in friendship."
So will Kidman, 40 – who's expecting her first child with husband Keith Urban – be a good mom?
"Of course!" said Watts. In fact, since the Oscar-winner has two adopted children, Isabella and Connor, with her ex-husband Tom Cruise, "She's already a great mum."
While little Alexander – whose dad is actor Liev Schreiber – didn't put in an appearance at the event, Watts said he's growing up fast.
"He's turning pages in the book," she said proudly. "He's crawling and standing up. He can wave. I read Goodnight Moon to him every night."