If you have a preemie baby, you may be wondering when they'll hit certain growth and development milestones – and how your baby's provider will measure these throughout their first year or two of life. Most preemies will track more closely to their adjusted age and follow a preterm growth chart. And although your preemie may catch up to their full-term peers quickly, you’ll likely use this adjusted age chart until your child is around 2 years old.
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How will I know if my preemie baby will have a different growth chart?
If your baby was born more than 3 weeks early, their physical and developmental growth will be measured alongside a different chart than babies born full-term. Otherwise, it would consistently appear as if your baby was not growing appropriately or was falling behind, compared to full-term babies born at the same time.
Many healthcare providers use the Fenton preterm growth chart to monitor preemie development; this chart is gender-specific, meaning it will be different for males versus females, and includes assessments for weight, length, and head circumference. Typically, preterm growth charts are used until a child is 2 years old.
What does "adjusted age" mean?
Adjusted age, sometimes called corrected age, is a way of figuring out when your premature baby can be expected to meet growth and developmental milestones. Although there's no exact science for predicting when babies – premature or full-term – will hit these milestones, there's still a "normal range" that spans when most babies accomplish these big developmental goals.
For preemies, many pediatricians recommend using an "adjusted age" to determine this range. Adjusted age helps level the playing field by considering just how early your baby was born. After all, had your baby not been premature, they would have had a lot more time in your womb to get ready before they were expected to achieve milestones.
To find your child's adjusted age, count the number of weeks between their birth date and their due date, and subtract that amount of time from their current age.
For example, if you have a 4-month-old baby who was born 8 weeks early, their adjusted age would be 4 months minus 8 weeks, which comes to about 2 months. At 6 months old, their adjusted age would be 4 months, and at 12 months old, their adjusted age would be 10 months.
When will my preemie baby catch up in height and weight?
There's no one answer here; all babies grow according to their own personal timeline, so some preemies may catch up within a matter of weeks, while others take a full year or two before they can be moved to a conventional growth chart for full-term babies. In many cases, healthcare providers use an adjusted growth chart until a former preemie is at least 2 years of age.
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A small number of preemies never fully catch up and remain slightly smaller than average throughout their life. Sometimes there's a clear medical reason. For example, if your child had a hard time getting enough nutrition in their early months because of illness or post-birth complications, they're more likely to remain on a lower growth curve.
Very premature babies are also more likely to remain comparatively short, though they may catch up in terms of weight by their late teens. It's important to remember that, too, that plain old genetics can be the reason for a child's smaller size or shorter stature.
In other words, there's no way to know what size your child will be catching up to. If people in your family or your partner's family tend to be short, your child may be short naturally. It's hard to tell whether a baby or young toddler will be tall or short based on their length and height, but by the time your baby is 2, their size can indicate how big they will be throughout childhood and as an adult.
When will my preemie baby reach development milestones?
Again, it's hard to predict – all babies learn and develop on their own schedule, whether they were born prematurely or not. But in general, experts recommend following along with your baby's adjusted age to figure out when they might hit developmental milestones as well as growth-related ones.
For example, while most full-term babies will sit up between 4 and 7 months, a baby born two months early can be expected to do this between 6 and 9 months. If your preemie is 4 months old with an adjusted age of 2 months, you can expect them to be meeting the milestones of a 2-month old baby, like smiling, making cooing sounds, and following you with their eyes while you move.
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Having a preemie baby may cause you to worry throughout their first couple of years of life (and beyond). Always remember that your child's providers are there to help guide you if you have questions or concerns about how your child is growing and developing. They can help ease your mind, and help support you throughout every stage of your child's life.
