Baby, at 3 months old, gains in flexibility and loves to chirp! He continues to gain weight and inches and is more and more aware of the world around him. During this third month, pay particular attention to preparing your return to work. Growth, awakening, and development of a 3-month-old baby Your little boy, at 3 months old, weighs about 5.75 kilos and measures about 59.9 cm Your little girl, at 32 months old, weighs about 5.35 kilos and measures about 58.6 cm Baby's head circumference has grown by about one and a half centimeters to 40 cm. The development and awakening of your 3-month-old baby Your baby is 3 months old. He is now able to lift his head when he is on his back and keep it straight for a few minutes! Yours falls asleep less and less during walks outside, which makes it possible to awaken your baby as soon as he is born: these stimuli to the world around him will allow him to develop his sensoriality. Your baby is coordinating his movements better and better. He w