“Already so in love with you,” the model, 22, captioned the mirror selfie.
In August, she announced her first pregnancy with longtime beau, singer Robin Thicke.
The Blurred Lines singer, 40, raises his 7-year-old son Julian with ex-wife Paula Patton.
Thicke and Patton have been in a bitter custody battle over their son.
Reportedly, Thick has a history of domestic violence, infidelity and addictions.
The Warcraft actress has accused the singer of physically assaulting her, cheating on her multiple times and having a serious cocaine problem.