Hi, my birch is 7 1/2 weeks pregnant and I noticed some clear mucous being passed this morning. It may have been happening for some time but she’s a really clean dog. Is this a normal thing? I’m fairly sure it’s fine but wanted to check. It’s her first litter. She’s absolutely huge, bless her x

Sounds normal to me.  Remember that she can whelp at day 56, with perfectly developed pups.  Be aware, and watch her like a hawk. 

Yes it's normal.  It can get all dried around their fur there, as well.  Just brush it out when its dried...