1, physical development: the height of a seven-month-old boy is usually 62.7-77.4cm, the weight is 6.24- 12.2kg, and the head circumference is 40.4-48.4cm. Seven-month-old girls are usually 6 1.3-75.6cm tall, 5.90-1.4 kg in weight and 39.5-47.2cm in head circumference.

2, action development: the seven-month-old baby's head is more flexible and can rotate freely to observe the surrounding things; Can keep an unsupported seat and reach the toys on the table; The legs can support most of the weight, can jump up and down with the help of support, and can turn over; Finger movements are more flexible, you can grasp, you can bump things against each other, and you can change toys from one hand to the other.

3, language development: Seven-month-old babies will take the initiative to imitate speech, will babble, and can express language with actions.

4. Perception ability: The seven-month-old baby's perception ability has gradually matured, and he can pay attention to things moving in the distance, such as planes and birds in the sky. You can skillfully find the sound source and understand the different meanings expressed by different tones and intonations. In addition, at this time, the baby begins to recognize strangers, and will be happy when he sees his caring relatives, and will smile when he sees himself in the mirror.

5, social communication skills: Seven-month-old babies can learn to wave and hand movements, but also pay attention to other people's emotions and emotions, and can respond accordingly. If they see others laughing, they will be happy or dancing.

The law of baby's height growth:

Height (length) is the sum of the lengths of fingers, trunk and lower limbs, and the proportion of the three is different at different stages of the baby. The younger the age, the greater the ratio of head to upper body, and the lower body will grow faster than the upper body with age.

The average length of a baby at birth is about 50cm. The height (length) increased the fastest in 1 year, and the average monthly height increased by 2.5cm at 1-6 months, and by 1.5cm at 7- 12 months, which was about 25cm higher than at birth.

In the second year after birth, the growth rate of baby's body length began to slow down, and it only increased by10-12cm throughout the year. From 2 years old until puberty, the baby's body length increases by 6-7cm every year on average. The formula for calculating the length of 2-7-year-old babies = age × 5+75cm.