Jay-Z Doted on Pregnant Beyonce at VMAs, Says Backstage Source

No wonder they're still crazy in love!

Sunday's MTV Video Music Awards show was an unforgettable night for Jay-Z and his wife, Beyonce, who joyously confirmed her pregnancy onstage before a TV audience of millions. (On the black carpet just a couple of hours before, the singer had announced that she was expecting, with her rep confirming the news to Us as well. The Grammy-winning superstar is about four months along, one source says.)

VIDEO: Watch Beyonce's unforgettable belly-rubbing performance!

And backstage, the parents-to-be were just as pumped up. With adjacent dressing rooms (Jay-Z, 41, shared his with pal and Watch the Throne partner Kanye West), "Jay was doting on her the whole time," a witness tells Us Weekly.

The rapper-mogul, whose real name is Shawn Carter, even cat-called his wife of three years! Says the backstage source, "He yelled, 'Mmm hmmm, who's that sexy lady walking down here?' playing like he was flirting with her. It was so cute."

PHOTOS: The craziest show moments at Sunday's VMAs

Jay-Z was also mindful of his love's condition. "He was really taking care of her, asking her how she feels and helping her walk," the source says. "It was so sweet to see him like that."

Also taking care? Beyonce's mom, Tina Knowles. "She was on top of EVERYTHING, getting Beyonce everything she needed. ... Between Jay and her mom, she was totally taken care of. Her mom was getting her everything she needed."

PHOTOS: What all the stars wore on the VMAs carpet

The superstar couple's famous friends got in on the baby joy, too.

PHOTOS: How Beyonce and Jay fell in love

"Kanye looked like the proud uncle!" adds the witness. And Beyonce's "Telephone" duet partner, Lady Gaga (dressed in male drag as Jo Calderone), made frequent visits to the dressing room as well. "She kept coming over to rub Beyonce's belly and say hello," the witness explains, "And the security guards thought she was a guy at first and wouldn't let her back! It was really funny."

RELATED ON WONDERWALL & MSN:

Photos of Beyonce and Jay throughout the years

Do you like celebs with straight or curly hair better?

The 30 worst VMA outfits