Newborns have weak intestinal adaptability, so if you do not change formula properly, it may lead to diarrhea. The formula should be done in an alternating and gradual way, adding 1/3 of the new formula to the formula originally eaten on the first day, and spending two or three days for adaptation. If the baby can accept it, adjust the ratio to 1:1 and adapt to it for two or three days, and the ratio of old to new formula to 2:1 and adapt to it for two or three days, and finally complete the transition to the new formula. You can take oral probiotics such as Mamma’s Love to adjust the intestinal flora.