Nicole holds her stomach during a walk in Canada.

Nicole Kidman sure looks swell as she pops out for a stroll during a family holiday in Canada yesterday.

The Oscar-winning actress has refused to confirm rumours that she is pregnant by new husband Keith Urban, but these pictures show she's definitely showing a more rounded stomach than normal.

Aside from the baby bump, Nicole and Keith's relationship may also be in for a bumpy ride as whispers in Hollywood claim the two have fallen out over Keith's ex-girlfriend.

Kidman reportedly fumed after she found out country star Urban was still friends with model Niki Taylor.

"Nicole found a video he shot with Niki. She was mad because he hadn't thrown it out," an insider said.

It is not the first time Miss Kidman has been rumoured to be pregnant since getting together with Urban a year ago.

The pair were pictured in December with Urban, 38, gently patting her stomach as they introduced their parents to each other.