1. Standards for the weight of a four-month-old baby The weight of a four-month-old baby is one of the important indicators for measuring the healthy growth of the baby. According to data provided by the World Health Organization (WHO), the average weight of a four-month-old boy is 6.2-8.0 kg, and the average weight of a baby girl is 5.4-7.2 kg. However, every baby\’s growth and development is different, so when judging whether a four-month-old baby is growing healthily, many factors need to be considered. 1. Birth weight: weight at birth