McLarty, who has dated Arquette for roughly two years, is reportedly in her fourth month of pregnancy. The news broke on the set of a movie in Vancouver, where Arquette, 42, is filming.
The child will be half brother or sister to 9-year-old Coco, Arquette's child with ex-wife Courteney Cox.
Ray Liotta sues skin care company over use of likeness
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