The main effects of diarrhea on the fetus in late pregnancy are the following: 1. Diarrhea in late pregnancy is mainly due to intestinal cramps, which lead to painful contractions that may induce preterm labor, a dangerous symptom for late pregnancy. 2. Frequent diarrhea in late pregnancy may affect the weight of the fetus, as late pregnancy is a critical period for fetal weight gain. Frequent diarrhea may lead to malnutrition in pregnant women, which may affect the nutrient absorption of the fetus. 3. If frequent diarrhea in late pregnancy is mostly due to inflammatory stimulation caused by enteritis, it may lead to fetal development being affected, especially in the choice of medication that may have an adverse effect on the fetus through the placental barrier. Pregnant women need to pay attention to develop good eating habits and avoid eating unclean food and junk food.