1. Height and weight development 1.1 Height development indicators of seven-month-old babies At the age of seven months, the average height of babies is 68.5 cm, and there is not much difference in the height of male and female babies. But it\’s important to note that every baby grows at a different rate, and some may grow taller or slower than average. 1.2 Weight development indicators of seven-month-old babies At the age of seven months, the average weight of male and female babies is 8.6 kg and 7.