Have you read the T&C for MN, OP? You should have, because you won’t like what you’ve signed up to by registering and posting on here.
For example:
Submissions to Mumsnet: We may now or in the future permit users to post, upload, transmit through, or otherwise make available on the site (collectively, "submit") messages, recipes, text, illustrations, files, images, graphics, photos, comments, sounds, music, videos, information, content, and/or other materials ("User Content"). We have the right to publish, edit or reject any User Content that you send us either via email, via the site or in writing via post for any purpose whatsoever, commercial or otherwise, without payment to you - unless we have specifically agreed otherwise in writing prior to submission.
By submitting User Content to us, simultaneously with such posting you automatically grant to us a worldwide, fully-paid, royalty-free, perpetual, irrevocable, non-exclusive, fully sublicensable, and transferable right and license to use, record, sell, lease, reproduce, distribute, create derivative works based upon (including, without limitation, translations), publicly display, publicly perform, transmit, publish and otherwise exploit the User Content (in whole or in part) as Mumsnet, in its sole discretion, deems appropriate. We may exercise this grant in any format, media or technology now known or later developed for the full term of any copyright that may exist in such User Content.
MN don’t sell it to the press (because the press can report on it for free). But they could if they wanted to.
If you don’t like that: don’t post.
And don’t complain about it. MN have been very clear about this - repeatedly.