While all babies may grow at a different rate, the following is the average for boys and girls 7 to 9 months of age:
Weight. Average gain of 1 pound each month. Boys usually weigh about ½ pound more than girls. Generally, expect 2 times the birth weight by 4 to 5 months and 3 times the birth weight by 1 year.
Height. Average growth of about ½ inch each month.
Head size. Average growth of about ¼ inch each month.
Babies are rapidly developing their physical abilities at this age. They become mobile for the first time, and safety in the home becomes an important issue. Babies may progress at different rates. But these are some of the common milestones most babies reach in this age group:
Gets into a sitting position by themselves
Sits without support
Reaches for and grasps objects using fingers
Can move an object from one hand to another
Starts teething, often starting with the two center front teeth in the lower jaw, then the two center front teeth in the upper jaw
Puts everything into mouth
Naps are often twice, sometimes 3 times a day, for 1 to 2 hours each (on average)
May start to wake up during the night and cry
It is very exciting for parents to watch their babies become social beings who can interact with others. Every baby develops speech at their own rate. But these are some of the common milestones most babies reach in this age group:
Makes a lot of different sounds like "mamamama" and "babababa" (ma-ma, da-da)
Smiles or laughs when you play peek-a-boo
Lifts arms up to be picked up
A baby's awareness of people and surroundings increases during this time. Babies may progress at different rates. But these are some of the common milestones most babies reach in this age group:
Looks for objects when out of sight
Bangs two things together
Is shy, clingy, or fearful around strangers
Shows several facial expressions, like happy, sad, angry, and surprised
Looks when you call their name
Reacts when you leave (looks, reaches for you, or cries)
Here are some ways to foster your baby's emotional security:
Give your baby safe toys that make noises when shaken or hit.
Play in front of a mirror, calling your baby by name and pointing to your baby's reflection in the mirror.
When talking to your baby, pause and wait for them to respond just as when talking with an adult.
Play pat-a-cake and peek-a-boo.
Name common objects when shown to your baby.
Make different sounds with your mouth and tone of voice.
Repeat and expand the sounds your baby makes, such as "ma-ma" when they say "ma."
Show picture books and read stories to your baby every day.
Give your baby toys with objects or knobs to push, poke, or turn.
Give your baby toys that stack or nest and show them how they work.
Build a tower with your baby and show them how to knock it down.
Create a routine for bath and bedtime.
Offer a cup.