Yes quite common actually! Hormones during first trimester can mess with ur digestion and cause everything from constipation to the opposite lol. Also if ur taking prenatal vitamins some of them can cause loose stools too. As long as ur not having like super frequent diarrhea or blood in stool should be ok. Just make sure stay hydrated esp if it’s happening often. Mention to ur gynae at next appt just to be safe 😊