Pressure down below when standing up?

Hoping someone can relate to this feeling.. I'm 21 weeks and when I first stand up in the morning I feel sore down below, almost like a sudden tender/pressure feeling. It literally goes away after a minute and I dont feel it for the rest of the day Not sure if it's the extra blood in my body rushing down there when I stand? I have no other symptoms so dont think it's a uti or anything Does anyone else have this when they stand up? Feeling worried and havent heard back from my midwife