I just rang my OB's office and I got to speak to a midwife. She said that diarrhea does not cause miscarriage. Well she said it can have an effect - but it does depend whether it's a good pregnancy or a bad one. If it's good then the diarrhea is not going to make a difference. She said it could just be the pregnancy hormones triggering the diarrhea even. She said they kick in around 8 or 9 weeks. She told me to take some Slippery Elm if I need to (I've heard of this before - good for bowel probs). She said something about cramping and how it just affects the bowel and the uterus which is just near each other. So she said I should be totally fine.