Hey mama! Normal lang yan, especially at 30 weeks, marami sa amin na experience yan, parang ang tiyan ay tumitigas then luwag ulit after a few minutes, right? Those are Braxton Hicks contractions, which is your body practicing para sa actual labor, but definitely mention it sa OB mo next visit para ma-check na lahat okay lang at walang other concerns. Drink plenty of water, take it easy, at kung sobrang sakit or frequent na, don't hesitate to call your doctor agad ha!