Wa'alaikumassalam sis! Perut mengeras masa pregnant mmg normal, tapi kalau dah frequent dari week 10 macam tu boleh jadi Braxton Hicks (latihan kontraksi), a few of us went through the same thing. Tapi sebab ni pregnancy concern, better check with your gynae aje to make sure everything is okay, especially kalau ada sakit or any other symptoms yang worry you. Take care!