Wondering about 31 weeks pregnant baby weight in kg? At 31 weeks, your baby is growing steadily and gaining weight as the third trimester progresses. Learn about the average baby weight, size, development, movements, and common changes you may experience during this stage of pregnancy. Every pregnancy is different, so your baby’s growth may vary based on several factors. Get simple and helpful information about 31 weeks pregnant baby weight and what to expect as you move closer to your due date.