The 36-year-old actress, writer and director discussed her working relationship with Baumbach, her partner since 2011, in the January issue of Vogue.
Gerwig met Baumbach as the writer and director was casting his 2010 film Greenberg. Gerwig and Baumbach co-wrote the screenplay for Frances Ha and started dating the next year, leading some to describe Gerwig as Baumbach's muse.
"I remember being very frustrated by that and wanting to correct it," Gerwig said of being overlooked as co-writer.
Gerwig said she was also asked if her relationship with Baumbach, now 50, opened doors for her in the film industry, although she gets the question less frequently today.
"But the answer is: yes, of course, for so many reasons. But he's also this incredibly important collaborator and influence on me. The most important," she said. "But I think I was hell-bent on making my own films, so I would have done it anyway."
Gerwig and Baumbach co-wrote Frances Ha (2012) and Mistress America (2015), and are co-writing the upcoming Barbie film starring Margot Robbie. Gerwig said working with Baumbach remains a enjoyable experience.
"I think the pleasure of writing for us is that it seeps into everything," she said.
Gerwig shared how she and Baumbach will work on sections on a script separately and then swap them at the end of the day.
"And then I get to hear him laugh at things I've written, and then I get to laugh at things he's written," she said.
Gerwig and Baumbach welcomed their first child together, son Harold, in March. The couple supported each other as they navigated parenthood and worked on their new films Little Women and Marriage Story. Baumbach's Marriage Story premiered Friday on Netflix, while Gerwig's adaptation of Little Women will open in theaters Dec. 25.
"In general, it was an exciting year," Baumbach said. "I don't want to sound sickeningly happy, but it's a truly great thing to watch someone you love make something and love the thing they make. I don't know how else to say it without saying great a lot."