Children
Baby Development: The First Year
What most babies do in the first year, the signs worth acting on, and how to arrange an evaluation yourself.
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- Evidence Based
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Babies vary enormously in when they reach milestones, and most of that variation is normal. What matters more than any single milestone is the overall pattern: several things behind at once, difficulty across more than one area, or a skill that has gone backward. In the first year the things most worth watching are head control, whether your baby uses both sides of their body equally, whether they respond to sound and to their name, and whether they use gestures before words. If something concerns you, you do not need to wait for a referral. In the United States a parent can arrange a developmental evaluation themselves, at no cost, for any child under three.
Contact your baby's doctor promptly if
- Your baby has lost a skill they previously had — this is investigated differently from a delay
- They seem very stiff, or very floppy
- Persistent head lag after around four months
- A strong preference for one side of the body, or one arm or leg moving differently
- They do not respond to loud sounds, or do not turn toward voices
- Difficulty feeding, frequent coughing during feeds, or poor weight gain
- Any concern that is not settling
You do not need to be certain. “I am worried about this” is a complete reason to ask.
What to expect in the first year
The first year covers more change than any year that follows it. A newborn who cannot hold their own head up becomes, within twelve months, someone who pulls to stand, hands you things deliberately, and understands the word no. None of it happens on a schedule. Babies work on one area at a time and often go quiet in one while another surges — a baby learning to walk frequently pauses on new words, and a baby deep in babbling may sit still for weeks.
That is why a single late milestone is rarely the useful signal. What tells you more is whether progress is happening at all, whether both sides of the body are being used equally, and whether your baby is connecting with you — looking, listening, and responding.
Milestones, month by month
The left column is what most babies do by each age. The right column is not a diagnosis and not a deadline; it is a prompt to raise something at your next visit.
| By this age | Most babies | Worth asking about if not |
|---|---|---|
| 2 months | Hold their head up during tummy time · watch you as you move · calm down when spoken to or picked up | No reaction to loud sounds · does not watch things as they move |
| 4 months | Hold their head steady without support · push up onto forearms on their tummy · make sounds back when you talk to them | Persistent head lag · does not bring hands to mouth · does not coo |
| 6 months | Roll from tummy to back · push up on straight arms · take turns making sounds with you | Does not roll at all · seems very stiff or very floppy |
| 9 months | Sit without support · look when you call their name · bang two things together | Not sitting unsupported · no response to their name · no babbling |
| 12 months | Pull to stand · wave or use other gestures · say mama or dada | Not moving about independently · no gestures · no words |
Milestones follow the revised set published by Zubler and colleagues in Pediatrics in 2022, which is the basis of the current CDC checklists. Checked August 17, 2026. The full citation is in Sources.
What is worth watching
Four things are worth more attention than the rest of the list, because each one, when it is off, tends to affect everything built on top of it.
Head control. Nearly all early motor skill is built on the ability to hold the head steady and turn it freely both ways. Symmetry. A baby who reaches with one hand, kicks with one leg, or always turns the same way is telling you something specific, and it is usually straightforward to treat early. Response to sound. Hearing underpins speech, and it is the most common treatable cause of a language delay. Gestures. Pointing, waving, and reaching to be picked up come before words and predict them — a baby who is not gesturing by their first birthday is worth mentioning even if you are not worried about speech yet.
When to act now
Most concerns in the first year can wait for the next scheduled visit. Two cannot.
A skill that has gone backward is not a delay, and it is not something to watch for a few more weeks. A baby who was babbling and has stopped, who was rolling and no longer does, or who was making eye contact and now does not, should be seen by their doctor promptly. Losing ground is investigated differently from being slow to gain it, and the reason to move quickly is that the answer changes what happens next. This is the single thing on this page that should not wait.
The other is anything in the list at the top of this page — a very stiff or very floppy baby, no response to loud sounds, difficulty feeding, or poor weight gain. Everything else on this page can reasonably be raised at your next appointment.
Common concerns in the first year
My baby only looks one way
A consistent head turn or tilt to one side is usually congenital muscular torticollis, which is common and responds very well to early physical therapy. It is worth raising rather than waiting, because the neck gets less flexible with time and because the same babies are checked for hip differences as a matter of routine. Torticollis
My baby has a flat spot on their head
Flattening is usually tied to how the neck moves rather than to the skull itself — a baby who prefers one direction rests on the same spot. Treating the neck is what addresses the head shape, which is why the two are assessed together. Torticollis
My baby hates tummy time
Very common, usually solvable, and worth solving, because tummy time is where the strength for rolling, sitting, and crawling is built. Short and frequent beats long and occasional, and there are positions — on your chest, across your lap, over a rolled towel — that make it easier to start. If your baby cannot tolerate it at all, that is worth mentioning. Physical therapy for babies
My baby is not rolling or sitting yet
Look at the pattern rather than the date: whether progress is happening, whether both sides are being used equally, and whether your baby is trying. A baby who is working at it and getting there slowly is different from one who is not attempting it. Delayed motor milestones
My baby does not respond to their name
Have hearing tested first, always — it is quick, it is the most common treatable cause, and everything else follows from the result. Looking when their name is called is something most babies do by around nine months. Speech therapy for babies
My baby drools a lot, or sleeps with their mouth open
Worth mentioning, because how a baby breathes and where the tongue rests affect how the jaw and palate grow. It is frequently dismissed and it is easy to check. Nighttime drooling
My baby gags or refuses textures
Feeding draws on sensory processing, oral motor skill, and posture at the same time, so difficulty here is often not really about food. Frequent coughing during feeds, or poor weight gain, should be raised promptly. Occupational therapy for babies
My baby seems very stiff, or very floppy
Muscle tone that is noticeably high or low affects how every other skill develops, and it is one of the things worth raising promptly rather than at the next visit. Hypotonia
How to get an evaluation
You can refer your own child, and the evaluation is free. Under the federal early intervention program for children under three, a parent can make the referral directly — no doctor's referral, no diagnosis, and no income requirement to be evaluated. Search for your state's early intervention program by name and call. There is a legal timeline once you make contact, so ask for the date of the evaluation when you call.
What services cost after the evaluation depends on where you live. Some states provide them at no cost; others use a sliding scale based on income. The evaluation itself is free everywhere.
Your pediatrician can also refer. Either route works, and you can do both. Bring specific examples and dates if you have them, and bring video — a baby often does very little in an unfamiliar room, and a thirty-second clip of what you are describing at home is worth more than a careful description of it.
What helps at home
Floor time, not container time. Babies build strength against a surface they can push into. Time in seats, swings, and bouncers is fine in moderation, but the floor is where rolling and crawling come from.
Alternate sides. Switch the arm you carry on, the side you feed from, and which end of the crib you approach from. Babies turn toward what is interesting, and if that is always the same direction they will always turn the same way.
Talk, pause, and wait. Leave a gap after you speak. Turn-taking with sounds is how conversation is learned, and it starts long before words — a baby who is given a pause will fill it.
Respond to gestures as though they were words. When your baby reaches, looks, or points, name what they want and hand it over. Gestures that get results become gestures that get used.
Frequently asked questions
When should I worry about my baby's development?
When several things are behind at once, when difficulty crosses more than one area, or when a skill has gone backward. A single milestone slightly late, with everything else on track, is usually not the concern. The pattern matters more than any one item.
My baby was born premature. Should I use their actual age?
Generally no. Premature babies are usually assessed against corrected age, which adjusts for how early they arrived, so a baby born two months early is compared with babies two months younger. Your pediatrician can tell you how long that adjustment applies.
Do I need a referral for early intervention?
No. Under the federal early intervention program for children under three, a parent can refer their own child directly. You do not need a doctor's referral and you do not need a diagnosis.
Does an early intervention evaluation cost anything?
The evaluation itself is free everywhere in the United States, and there is no income requirement to be evaluated. What services cost afterward varies by state — some provide them at no cost, others use a sliding scale based on income. Ask when you call.
What actually happens at an evaluation?
A team looks at how your baby moves, communicates, plays, hears, and manages feeding, mostly through play rather than testing. You are there throughout and what you report counts as evidence. There is a legal timeline once you make contact, so ask for the date when you call.
My baby is not babbling. Should I be concerned?
Babbling with consonants, the mamamama and babababa sounds, is what most babies do by around nine months. Not babbling by then, or not turning when you call their name, is worth raising. Ask for a hearing test first — hearing is the most common treatable reason and it is quick to check.
My baby could do something and now cannot. Does that matter?
Yes, and it is the one thing on this page that should not wait. Losing a skill that was already there is investigated differently from being slow to gain one. Contact your baby's doctor rather than watching it for a few more weeks.
What if I am worried but everyone says they are fine?
Ask anyway. The evaluation is free, you can arrange it yourself, and being told everything is fine by someone who has assessed your baby is a different thing from being told it by someone reassuring you. You have watched your baby across months. An assessment takes about an hour.
Sources
- Zubler JM, Wiggins LD, Macias MM, et al. Evidence-Informed Milestones for Developmental Surveillance Tools. Pediatrics. 2022;149(3):e2021052138. doi:10.1542/peds.2021-052138 (PMID 35132439)
- Individuals with Disabilities Education Act, Part C — early intervention for infants and toddlers with disabilities, 34 CFR Part 303. Evaluation, assessment, and development of the individualized family service plan are provided at no cost to families; states may adopt a system of payments for other services.