Knocked Up

'For fun loving party animal Ben Stone, the last thing he ever expected was for his one night stand to show up on his doorstep eight weeks later to tell him she\'s pregnant.'

Knocked Up is a 2007 American comedy film, co-produced, written and directed by Judd Apatow. Starring Seth Rogen, Katherine Heigl, Paul Rudd, and Leslie Mann, the film follows the repercussions of a drunken one-night stand between Rogen's slacker character and Heigl's just-promoted media personality that results in an unintended pregnancy.

Source: Wikipedia