Hellions (2015) on Netflix

Plot summary

Dora Vogel is a teenager who plans to spend Halloween getting high with her boyfriend, Jace, and going to a party with him. That day her doctor, Henry, tells her she is four weeks pregnant, a result she says should not be possible. Upset by the news, she goes back to her house to await Jace. Her mother, Kate, takes Dora's younger brother, Remi, trick or treating. Before Jace arrives, children in strange costumes come knocking at Dora's door.