A pro-choice protester has breached security and stormed the stage at a controversial "pro-families" conference in Melbourne on Saturday, a day after state and federal Liberal MPs pulled out of the event in the face of a political backlash.

Despite a large police presence at the World Congress of Families in Hallam, the woman was able to enter the venue as a registered guest, rushing on to the stage where she positioned herself in front of NSW MP the Reverend Fred Nile and other guests, spilling fake blood on her white outfit.

"We don't want your backyard abortions," she yelled, before being marched out by security.

Guests at the event, who had earlier been confronted by dozens of protesters as they entered the venue, were visibly rattled by the breach, turning to prayer as the woman was ushered outside.

"Can I ask everybody to take one moment to pray for the forces that create that type of thing; that is extremely sad," Teresa Martin, the Queensland president of right-to-life group Cherish Life, told the audience.