In her statement, Moreno didn't mention anything related to gender discrimination. Her exit is the latest by a female higher-up at the social news site at a time when the company's efforts to rein in the most toxic elements of its community have been in the spotlight.
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In early July, Reddit parted ways with admin Victoria Taylor. Shortly thereafter, interim CEO Ellen Pao left the company. A few days after that, so did engineering chief Bethanye Blount.
Blount told Re/code she was leaving because she felt the company couldn't deliver on the promises it was making publicly related to community management and harassing content. Blount also said that gender discrimination was likely a factor in Ellen Pao's departure from Reddit, although it didn't contribute to her own or Victoria Taylor's exit.
Read MoreReddit revolt grows as petition to fire Pao cracks 100,000
Two weeks ago, Reddit's co-founder and new CEO Steve Huffman announced a new content policy for Reddit that attempted to clarify what "offensive content" was acceptable to post on the site. Huffman said that content that incites harassment (like r/FatPeopleHate or r/rapingwomen) is bannable, but subreddits such as the white supremacist haven r/CoonTown are permissible because their hateful discussions supposedly don't go beyond the realm of theory.
Aside from a submission to r/PigeonDrawings yesterday, Moreno last posted on the site more than a week and a half ago, responding to queries about the new content policy.
Read MoreDetails emerge about Victoria Taylor's Reddit dismissal
You can read both the full statements below:
From Jessica Moreno:
I have enjoyed my time at Reddit but after four years I feel that it's time for me to move on. While I am working with Steve on a transition plan, I am looking forward to taking time off to spend with my family. It was a difficult decision to make right now as Reddit is taking difficult steps in a much needed positive direction. I'm excited to see the progress being made and glad I could be a part of it.
Jessica is going to return to Salt Lake City to be with her family, but we've yet to settle on a date. We're grateful for her invaluable contributions to our community, from Secret Santa to industry-leading policy changes, and wish her all the best in her future endeavors.
—By Noah Kulwin, Re/code.net.
CNBC's parent NBC Universal is an investor in Re/code's parent Revere Digital, and the companies have a content-sharing arrangement.