Ay, constipation with formula memang common! A few of us mums noticed S26 Step 3 ni agak heavy for some kids, try switching to something with higher prebiotics like Lactobacillus, or consider brands like Nutricia Aptamil or Enfagrow yang ramai mums kata more gentle on the tummy. Also make sure dia minum enough water and getting enough fibre from food lah, sebab sometimes it's not just the milk. Kalau still constipated after switching, better check with the paed to make sure nothing else going on, okay?