Amber Tamblyn and husband David Cross are expecting a baby daughter. The Sisterhood of the Traveling Pants star penned a powerful essay for Glamour in which she shares that her foray into motherhood is giving her a lot to think about — especially when it comes to how our culture treats women.Tamblyn begins her essay by explaining how difficult it was for her to tell her mother about her assault at the hands of an ex-boyfriend. The actress' personal story went viral after she shared it on Instagram in response to the leaked audio of Donald Trump's offensive sexual comments about women. Opening up to her mother about that story was difficult for Tamblyn, but she didn't expect her mom to have her own to share. Tamblyn writes:"Go ahead and fill in the blank of my mother’s story. It’s easy, isn’t it? I was at a ________, and a guy _________. I was _______ years old and the father of one of my friends __________. I was at work and my boss ___________. I was walking down the street and __________. I exist, therefore ___________ is bound to happen. On the phone, my mother ended with a second story. She told her mother what had happened to her, and I’ll bet you can fill in this blank, too. My grandmother’s response to my mother was, 'Boys will be boys. You just have to be really careful around them.'"It's this statement from Tamblyn's grandmother that got the actress thinking about what it means to be a mother — and how to raise a daughter to be strong, smart, and happy in a world where people still treat women like they deserve less respect than men.Both Tamblyn and her Arrested Development actor husband, whom she wed in 2012 , have been vocal about fighting for women's rights. In 2013, the pair created a hilarious PSA sketch arguing against restrictions to women's access to health care.Tamblyn also writes that she has a tribe of mothers to look up to while raising her own daughter — perhaps including her friend and Sisterhood co-star Blake Lively, who gave birth to her second child this year."I am very lucky to be surrounded by strong mothers," Tamblyn writes. "From my own mom to some of my best friends — those who are raising young women to accept themselves and those who are raising young men to accept women."