Hellions (2015)

Dora (Chloe Rose) is an average teenager who just wants to have fun and get high with her boyfriend, Jace (Luke Bilyk), the day of Halloween. She is stunned when her doctor, Henry (Rossif Sutherland), tells her that she is four weeks pregnant, something she says should not be possible. Distraught, Dora goes home to wait for Jace to pick her up for a Halloween party while her mother (Rachel Wilson) takes her younger brother, Remi (Peter DaCunha), trick or treating. But before her boyfriend can pick her up, Dora is visited by several children in strange costumes. Their presence is increasingly threatening, culminating with one carrying the severed head of Jace in a bag. Dora must fight the monstrous children, who want her unborn child, a feat made more difficult by the fact that her pregnancy is progressing at a very fast and unnatural pace.