Christina Aguilera posing for sexy ad campaign while pregnant

Here is new mum Christina Aguilera hiding her baby bump in a sexy photoshoot during her pregnancy.

The pop star was four-months pregnant when she posed last August for the glamorous new advertising campaign for Stephen Webster jewelry.

"We shot it in August. I got a call from her when she was on her world tour in Korea, and she told me she was pregnant," Webster said. "We'd originally planned to shoot the campaign in October or November but we decided that the minute she got back from touring would be the best window of opportunity."

Aguilera was already showing her pregnancy with son Max Liron Bratman during the shoot, but it was kept hidden using clever angles.

"It was okay. The way we shot it, you wouldn't know. We weren't going for full-body shots."