Hi mama! At 31 weeks, those stronger and more frequent movements are usually normal, baby's getting bigger and stronger kaya mas malakas ang kicks mo, lalo na kung active ang little one mo! That said, kung nag-worry ka talaga or if it feels different from the usual pattern ni baby, better check with your OB lang para ma-ease ang mind mo, they can do a quick check and confirm everything's okay, which will give you peace of mind.