The younger sister of Jessica Simpson kept a hand on her baby bump while posing for photographers in Los Angeles on Monday evening (20 April).
Ashlee wore a floor-length silk navy gown, with a black coat on top, while Evan wore a rather interesting fuzzy looking jacket.
Just Before I Go is the directorial debut from former Friends star Courteney Cox, who was also at the premiere. Hunger Games actor Evan stars in the movie alongside the likes of Seann William Scott and Kate Walsh.
Ashlee and Evan married in Connecticut in August last year, at the estate of Evan's singer mother Diana Ross. The couple's first pregnancy was revealed in December and they later confirmed it will be a baby girl. Ashlee is also mum to son Bronx, six, from her marriage to Pete Wentz.
Check out some of the best maternity fashion below: