Developmental Milestones for Preterm Infants

If your baby was born early, it's completely natural to wonder whether they're developing as they should. The reassuring news is that most premature babies go on to reach the same developmental milestones as babies born at full term, they may just need a little more time to get there.

Many preterm babies catch up to their full-term peers by around 12–18 months, although every baby develops at their own pace. Understanding your baby's corrected age can help you track their progress more accurately and celebrate each new achievement along the way.

In this guide, we'll explain corrected age, explore common developmental milestones by age, and help you understand when it might be helpful to seek additional support.

Corrected age (also called adjusted age or gestationally corrected age) is your baby’s age adjusted for how many weeks early they were born, using 40 weeks of pregnancy as the reference. (RCPCH, 2009)

It helps give a fairer picture of development because babies born early have had less time to grow and develop in the womb.

Corrected age is commonly used in the first 2-3 years of life when looking at growth and development. Many babies born early will reach milestones in line with their corrected age rather than their actual (chronological) age, and this is completely normal.

You can work this out in two steps:

• Find how many weeks early your baby was: 40 weeks minus the number of weeks when your baby was born.
• Take that number away from your baby's age since birth – in weeks

Example: A baby born at 32 weeks was 8 weeks early. If they are 16 weeks old since birth, their corrected age is 8 weeks.

If you're not sure, your health visitor or neonatal team can often help you confirm the corrected age they are using.

Corrected age examples

Remember, corrected age is simply a tool to help track development more accurately. Many premature babies reach milestones in line with their corrected age and most catch up to their full-term peers by around 12–18 months, although every child develops at their own pace.  

All babies develop at their own pace. Babies born early may reach milestones differently, and some may need a little extra time or support. Regular follow-up helps make sure development is on track and any concerns are identified early (Harding and Levin, 2018).

• Looks at your face for a short time.
• May start to smile back.
• Calms when they hear familiar voices.

• Moves arms and legs more smoothly.
• Brings hands towards mouth.
• During tummy time, may lift head briefly.

• Makes small sounds like coos.
• Startles or settles when they hear a sound.

• Sucking and swallowing are becoming more coordinated.
• Shows early hunger cues (for example, rooting, bringing hands to mouth).
• Feeds regularly (breast or bottle) - may still be 8 times in 24 hours.

• Smiles and enjoys play.
• May laugh.
• Watches people and follows what you do with your face.
  

• Holds head steadier.
• Pushes up on forearms during tummy time – may be able to roll over
• Reaches for toys and brings hands together.

• Makes more sounds (squeals, coos) - may copy you.
• May cry differently if they are happy, sad, hungry.

• Starting to show interest in food and what you are eating, however weaning should not be commenced until 26 weeks and not before 17 weeks. Always speak to your healthcare team to check when your baby is ready

• Enjoys familiar people.
• May be unsure around strangers.
• Notices your tone of voice (happy, calm, upset).

• Sits with support and may sit for a short time without help.
• Passes a toy from one hand to the other.
• Rolling over in both directions
• May start to put pressure through their legs

• Starts babbling (for example, ba or da).
• Makes sounds during play.
• May react to their name.

• Are showing an interest in food and starting to open their mouth when spoon fed
• Are starting to eat cereals and single-ingredient pureed foods like carrots, sweet potato and banana.

• Enjoys simple games like peekaboo and may have a favourite toy
• Looks for comfort from familiar caregivers.
• May cry when you leave.

• Sits well with minimal support.
• Moves to get what they want (rolling, shuffling, crawling, or bottom shuffling).
• Starts picking up smaller items using fingers and thumb and may be now pointing to what they want

• Babbling becomes more varied.
• May understand simple words with context (for example, no or bye-bye).

• Beginning to eat thicker pureed foods and stays full for a longer period of time after eating meaning milk intake may reduce a little
• Reacts strongly to new smells and tastes

• Copies simple actions like clapping or waving.
• Points or reaches to show you what they want.
• Shows favourite people, toys, or games.

• Pulls up to stand and may cruise along furniture.
• Some babies take first steps (many do this later).

• Understands simple instructions with gestures (for example, give it to me).
• May say a few words or use word-like sounds – mama, dada, no
• Uses gestures with meaning (waving, reaching, pointing).

• Eats a greater variety of foods and may now be eating the same foods as the family.
• Starting to learn how to eat on their own
• Can thoroughly chew their food
• Beginning to be able to use an open cup

Your baby's developmental milestones | UNICEF Parenting

Some preterm babies are more sensitive to noise, bright lights, touch, and busy places. This can affect sleep, feeding, and play. A calm space, simple routines, and breaks during play can help.

Preterm babies do not always develop evenly across all areas. Your baby might be strong socially but slower with movement, or the other way around. This can be normal, especially when you use corrected age.

Some preterm babies have muscle tone that feels lower (floppy) or higher (stiff). This can affect posture and gross motor skills like head control, sitting, and crawling. If your baby seems very floppy or very stiff, or you notice they always turn or use one side more than the other, if you have any concerns speak with your care team.

Small, everyday things make a big difference. Follow your baby's cues. Short, regular play is often better than long sessions as they may become tired.

• Motor skills: gentle tummy time (as tolerated), reaching for toys, and supported sitting play.
• Language: talk to your baby, copy their sounds, and share books every day.
• Feeding and growth: follow advice from your clinical team. Breastmilk is recommended where possible, and some babies need extra support.

(Morniroli, et al, 2020)

Occupational therapy and physiotherapy can help with movement, posture, feeding skills, and how your baby handles touch and sound. If you are worried, ask your health visitor, neonatal follow-up clinic, or GP about referral options.

Speak with a health professional if you are worried. It can also help to get advice if your baby:

• Loses skills they used to have.
• Seems very hard to wake or engage most of the time.
• Looks much floppier or stiffer than before.
• Does not use both hands or both sides of the body over time.
• Does not react to sounds or does not make eye contact (possible hearing or vision concerns).
• Has feeding problems that affect weight gain, hydration, or breathing (for example, coughing or choking with feeds).
• Is missing many milestones even when using corrected age.

Your healthcare team can check development using corrected age and arrange early support if needed.