The 28-year-old Warm Bodies star, who hails from Adelaide, South Australia, is pictured taking a break from a hike to give her baby some nourishment.
Teresa's Instagram page is full of pictures of her small family - which includes her actor husband Mark Webber and their son Bodhi Rain, who is just a month old.
Teresa posted this snap to her Instagram page
The couple were married in December 2013.
In one post, Teresa accompanies a photo of her husband and baby with: 'There is nothing I would rather do in my life than love you both with my whole heart.'
Read: This woman silences breastfeeding critics with this passionate poem.
Teresa also posted this snap of her and her son
Last year, the blonde beauty starred opposite Nicholas Holt in zombie-comedy Warm Bodies.