Developmental Milestones: Your Baby's First Year, Month by Month

Your baby is a little different every month: first they look at your face, then they hold up their head, and one day you look over and they have pulled themselves up to stand. Each of these changes is a developmental milestone. This guide is based on recommendations from the US Centers for Disease Control and Prevention (CDC) and the American Academy of Pediatrics (AAP). The goal is not to put your baby through a test; it is to help you know what to look for as you watch them grow.

How to read the lists: The CDC's updated lists show skills that most children, at least 75%, can do by that age. So if a skill is on the list, most babies are doing it by that month. Not doing an item yet is not a diagnosis on its own, but it is a good reason to talk with your doctor. The CDC also reminds parents that these lists do not replace the standard developmental screening your doctor does.

By the end of 2 months, most babies:

• Calm down when spoken to or picked up.
• Look at your face and seem happy to see you when you come close.
• Follow you with their eyes as you move.
• Smile when you talk to them or smile at them.
• Make sounds other than crying and react to loud sounds.
• Lift their head when lying on their tummy.
• Move both arms and both legs and open their hands briefly.

By the end of 4 months, most babies:

• Make cooing sounds like "oooo" and "aahh" and make sounds back when you talk to them.
• Turn their head toward the sound of your voice.
• Hold their head steady without support when you are holding them.
• Hold a toy when you put it in their hand, swing their arm at toys and bring their hands to their mouth.
• Push up onto their elbows and forearms when lying on their tummy.
• Open their mouth when they see the breast or bottle if they are hungry.

By the end of 6 months, most babies:

• Know familiar people and like to look at themselves in a mirror.
• Take turns making sounds with you, squeal, and blow "raspberries" by sticking out their tongue.
• Reach for a toy they want and explore things by putting them in their mouth.
• Close their lips to show they do not want more food.
• Roll from tummy to back.
• Lean on their hands to support themselves when sitting.

By the end of 9 months, most babies:

• Are shy around strangers and may be clingier with you.
• Show several facial expressions, like happy, sad, angry and surprised.
• Look when you call their name and react when you leave the room.
• Make syllable sounds like "mamama" and "bababa" and lift their arms up to be picked up.
• Look for a spoon or toy they have dropped and bang two things together.
• Get into a sitting position on their own and sit without support; move things from one hand to the other.

By the end of 12 months, most babies:

• Play games with you, like pat-a-cake, and wave "bye-bye."
• Call you "mama," "dada" or another special name.
• Pause briefly when you say "no."
• Put a block in a cup and look for a toy you hide under a blanket.
• Pull up to stand and walk while holding on to furniture.
• Pick up small things with their thumb and pointer finger.

Corrected age for babies born early: The AAP recommends assessing a preterm baby's development by their corrected age. The math is simple: you subtract the number of weeks your baby was born early from the number of weeks since birth. For example, a baby born at 32 weeks arrived 8 weeks early; at 4 months old, their corrected age is 2 months. It makes sense to expect the skills of a 2-month-old, not a 4-month-old. According to the AAP, using corrected age for the first 2 years gives you a more realistic picture. The CDC's checklists also ask whether the baby was born early; be sure to mention this when you talk with your doctor.

Losing skills always matters: If your baby has stopped doing something they used to do, for example they no longer smile at you or the sounds they made have disappeared, tell your doctor without waiting for the next checkup. The CDC counts the loss of a skill a child once had as a clear reason to act early.

When should you see a doctor? The CDC's message is clear: "Don't wait." Talk with your family doctor or pediatrician if:

• Your baby has not reached one or more of the milestones for their age
• They have lost a skill they once had
• You have any other worry about their development that keeps nagging at you

You can ask the doctor for a developmental screening and, if needed, a referral to a specialist. When delays are noticed early, support can start early too.

Write down what you notice: The CDC recommends that families track development regularly. Jotting down the new things your baby does each month makes it easier to talk with your doctor at checkups. Remember, these lists are just a road map; every baby moves at their own pace.

Dear mom, you know your baby best. Talking to them, cuddling them and playing with them every day is already the strongest support for their development. If something does not feel right, ask without waiting; asking is never too much.