Wa'alaikumassalam! Diarrhea memang boleh happen during pregnancy, especially early stages sebab hormonal changes, tapi kalau frequent sangat atau ada darah/mucus, better check dengan doctor ye. A few of my mum friends experienced this juga, biasanya settle dengan minum banyak air and eating bland foods, tapi setiap orang beda-beda so best to get it checked to rule out anything else!