With my first child I had an irritable uterus and so had contractions everyday from 24 weeks - not BH.

With this pg I have been a bit stressed about having the same prob as it lead to early labor for us. I thought I was having then again at around 13wks so called my OB who assured me that the uterus cannot contract as in a contraction until 20 weeks - something about the muscle of the uterus not being coordinated enough before this time. She thought I was just very in-tune with my body due to previous pg and increased anxiety.

Personally I think BH's are possible before 20wks - just that most women dont feel them yet. But thats just my 2c worth.

I am now definatley getting BH's often. Apparently the uterus will stay quite hard (as in BH) after sex or orgasm. DH and I dont DTD for fear of starting off irritable uterus again . Werent allowed to at all with last pg so playing it safe for this one too.