Physical Development of 9 to 12-Month-Old Babies

Baby girl crawling on floor
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During the later months of your baby’s first year, you will be amazed by the leaps and bounds she makes in her physical development. Not only has she grown from this tiny infant that once fit in the crook of your arm, but she is making both literal and figurative steps toward increased mobility and agility. Here are some advancements you might see since she passed the previous period of development.


Parents often find themselves wondering how their baby’s overall growth compares to other babies. However, it is more important to assess a baby’s growth based on her own track record. Provided your child is following a steady pattern on her growth chart, she is likely doing well.

That being said:

  • Babies of this age will have grown about 10 inches in length since birth.
  • Typical head growth is about 0.25 to 0.5 inches per month.
  • Babies’ weight gain will slow down at this age. Many babies will triple their birth weight around their first birthday.

Physical Appearance

Your baby will still melt your heart with that “baby look” — the large head, short arms and legs, and the full pot belly. However, you might notice as her mobility increases and she builds more muscle that she leans out slightly. At this age, she might sport a mouthful of teeth or still may be all gums.

Gross Motor Skills

Suddenly, your baby is amazing you (and quite possibly exhausting you) with how much she can move on her own accord. Her newborn reflexes have diminished, and she’s showing increased control over her gross motor movements. Additionally, she might impress you with:

  • Moving from the stomach to a seated position
  • Pulling up
  • Creeping or crawling
  • Cruising furniture
  • Standing up unassisted
  • Walking

Fine Motor Skills

Similarly, your little one is illustrating increased dexterity as her fine motor skills refine. Her ability to pick up small objects between their thumb and finger is cause for you to be very aware of potential choking hazards. Additionally, she may be able to use the same skill to feed herself finger foods.

Her fine motor abilities are also increasing her ability to entertain herself. With a little effort, she might work to reach and pick up an object. For objects completely out of reach, she should be able to let you know what she wants by pointing or gesturing.

Taste and Smell

Her sensory skills — sight, hearing, taste, smell, and touch — are a pairing of both physical and cognitive development. The senses that were in place before her birth have each refined and improved over the past months.

Her well-developed sense of smell is often used in conjunction with her sense of taste. She may show strong preferences for certain flavors and odors. Research shows that infants exposed to a full range of foods and flavors at this age are shown to have lower rates of obesity and accept diverse flavors later in life.

Touch and Hearing

Her sense of touch, one of the most highly developed of her senses since birth, continues to progress. She can sense pain and discomfort, changes in temperature, and assert preferences for textures.

From the physical standpoint of sensory development, she should be able to hear their name and react to simple requests. She should enjoy the sound of her own babbling voice and perk up at the sound of other's voices. Toward the end of this age range, she should begin to repeat sounds and words that she hears.


Her sight, which was the weakest of senses at birth, is now nearly as strong as an adult's in the areas of clarity and depth perception. While she prefers to look at objects nearby, she can see objects across the room. As far as color, the color she now sports is apt to stay the same with only subtle changes.