The intimate photo captured the connection between mother and child while nursing, with Christensen captioning the photo, “A private moment from the beginning of this relationship that’s still in its beginnings.”
She went on to celebrate her own mother, thanking her for being a great role model. “Today I definitely focused on my gratitude for my mom, who did and does so much to teach me not THAT the seemingly impossible is possible, but HOW. She taught me to break the mountain down into step after step. I hope I can teach the same invaluable lesson.”
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Christensen, 35, also thanked Shane for being part of her life, writing, “And now a moment of gratitude to my girl for swooping in and bringing her infectious joy and curiosity into our family, and for helping me learn how to be a mama.”
“Happy Mother’s Day to all the teachers and lovers and leaders who are helping wear that mother hat whether they even realize it or not. #mothersday,” she concluded her message, which was met with comments from fans like “Beautiful and raw” and “A beautiful depiction of motherhood.”
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Christensen had previously told PEOPLE that nursing was very difficult for her at first and took a while to “click.”
“The only time I actually cried was after I had already hired the lactation consultant, and she made it seem so easy. Then she left and I tried on my own and I still couldn’t figure it out,” she said in October.
Christensen and husband Cole Maness welcomed their first child in June 2016 during a home birth, with the actress live tweeting, “I’m in labor. Right now” the night she gave birth.