Nine-month-olds have a new understanding of the world. They learn that just because they can't see mom or dad at a certain time doesn't mean they don't exist. So now, your baby may begin to miss you when you're gone. This can lead to separation anxiety — distress at your departure.

While this might seem like a bad thing, it's actually very good — and marks an important leap in thinking. Comfort and reassure your baby to help him or her feel loved and secure. 

Doctors use certain milestones to tell if a baby is developing as expected. There's a wide range of what's considered normal, so some babies gain skills earlier or later than others. Babies who were born prematurely reach milestones later. Always talk with your doctor about your baby's progress.

Here are some things your baby might be doing:

Communication and Language Skills

  • communicates "no" by closing the mouth or turning away when finished eating
  • understands the word "no"
  • says "mama" and "dada" (but not just to parents)
  • can wave goodbye and say "bye-bye"
  • starts pointing to objects

Movement and Physical Development

  • sits without support, pulls to stand, and walks along furniture ("cruising")
  • starts to grasp small pieces of food (such as pieces of "O"-shaped cereal)
  • can hold one item in each hand at the same time

Social and Emotional Development

  • might be fearful of strangers
  • misses caregivers when they leave
  • seeks reassurance from caregivers (a baby starting to crawl, for example, will often "check back" with mom or dad while developing this new skill)
  • attaches to "transitional objects" for security, such as stuffed animals or a favorite blanket

Cognitive Skills (Thinking and Learning)

  • understands "object permanence," the idea that an object or person exists somewhere even though the baby can't see the object or person at that moment (for example, a baby with this understanding will look for a toy that a caregiver hides behind a blanket) 
  • enjoys interactive games such as "peekaboo" and "so big"
  • looks at the pages of a book while you read
  • bangs objects on floor or table to create sound 

When to Talk to Your Doctor

Every baby develops at his or her own pace, but if you notice anything that concerns you — however small — share it with your doctor. Always tell the doctor if your baby:

  • shows no reaction when you leave the room
  • cannot roll onto the belly
  • hasn't lost newborn reflexes, such as the startle reflex 

Also, if you ever notice that your baby has lost skills he or she once had or shows weakness on one side of the body, tell your doctor.

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