With DD1 I lost mine the day before. It was grey with a streak of blood in it. It came out in 2 goes. The last of it went in the toilet about 3 hours before my waters broke.

DD2 - Thick white mucus for 3 or 4 days before labour sarted. Thats all I saw or heard about.

DS - Nothing! I must've spent hours all up checking & waiting for something, but nothing.
I had a bloody show maybe an hour before I had him. Didn't see it though. MW told me.