Why Is It Important to Correct for Age in Premature Infants?

It's necessary to correct the age of premature infants so that the growth and development of the child can be adequately monitored. This only applies to the first years of their lives, however.
Why Is It Important to Correct for Age in Premature Infants?

Written by Edith Sánchez

Last update: 03 August, 2022

Correcting the age in premature infants is very important to follow the development of the baby properly. Otherwise, it’s possible that mistakes may occur in the assessment of their progress.

When a baby is born early, it has a different evolution. It completes stages of its development in variable times with respect to the little ones who were born on time.

Until not long ago, little relevance was given to the fact of correcting the age of premature babies. This often led to misplaced expectations about developmental progress. Today, it’s considered essential to do so.

Premature babies

According to the World Health Organization (WHO), around 15 million premature babies are born each year worldwide. Depending on when they come into the world, they are divided into three categories:

  • Moderate to late preterm: Born between 32 to 37 weeks
  • Very preterm: Born between 28 to 32 weeks
  • Extreme preterm: When they’re born before the 28th week

The more premature they are, the greater the risk that they will have difficulties in their psychomotor and cognitive development. In any case, babies born prematurely have a different rate of evolution than those born at full term. This is the essential reason for age correcting premature babies.

a premature infant
Premature babies have more risk factors for certain diseases, so extreme care must be taken when looking after them.

The usefulness of correcting for age in premature babies

Age correcting premature babies is necessary to evaluate their physical and neurological development. When a baby is born prematurely, two ages are attributed to it:

  • Gestational age: This corresponds to the exact time the pregnancy has lasted and is counted in weeks. It’s counted from the first day of the last menstrual period to the day of birth.
  • Chronological age corresponds to the time that elapses after birth. It’s counted in days, weeks, months, and years.

Now, when the exercise of correcting the age in premature babies is done, a third age appears, which is the adjusted or corrected age. This is the age the baby would have if it had been born at term – that is, at 40 weeks.

Based on these data, it’s possible to evaluate crucial aspects of development, such as weight, height, head circumference, and the acquisition of motor and psychosocial skills. This parameter also makes it possible to establish when the baby should receive complementary feeding.

The preterm baby usually develops a little “slower” than a full-term baby. Thanks to the corrected age, it’s possible to avoid the mistake between a diagnosis of developmental delay and normal development.

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The effect of prematurity on development

Correcting the age of premature babies is essential to avoid erroneous comparisons. If the baby is born premature, it needs to make up for the time it would have lacked to be born at term.

The aspects that are most conditioned are the following:

  • Premature babies take longer to reach a weight and length that is in accordance with their chronological age.
  • They’re more likely to have difficulties with breathing, sucking, swallowing, gastric emptying, reflux, and muscle tone. If age is not corrected for, these difficulties may be mistaken for diseases.
  • Complementary feeding can only be given when they reach six months of corrected age, not their chronological age.

The only aspect in which there’s no need to correct for age in premature infants is in the administration of vaccines. These are administered to all children equally by taking into account only the chronological age.

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The calculation to correct the age of premature babies

Correcting the age of premature babies is very simple. It’s only necessary to apply a simple calculation. Subtract the number of weeks of prematurity from the chronological age, and the result is the baby’s corrected age.

At the same time, to establish the number of weeks of prematurity, it’s only necessary to subtract the gestational age from 40.

Suppose a baby is born at 32 weeks gestation. The first thing to do, then, is to subtract 32 from 40, which gives us 8: 40 weeks (full gestation) – 32 weeks (gestational age of prematurity) = 8 (weeks prematurity).

The next step is to take the chronological age, expressed in weeks, and subtract the number of weeks of prematurity. For example, if we do the calculation on a 4-month-old child: 16 (chronological age in weeks) – 8 (weeks of prematurity) = 8 weeks or 2 months (corrected age).

How long is the corrected age used for?

Although it’s very important to correct the age in premature infants to monitor development properly and establish feeding milestones, the corrected age is not taken into account forever. It’s only valid at the beginning of the baby’s life.

In particular, the corrected age is only used up to two years of age. There, the developmental milestones of a premature infant are equated with those of a full-term infant.

If, after this age, disparities are often still observed in relation to a full-term infant, they are no longer considered to be the result of prematurity. In such cases, it’s necessary for the physician to further evaluate what’s happening.

premature infants correcting for age
Pediatric checkups up to two years of age consider the corrected age. After that, milestones can match those of other children.

Not everyone is the same

There are no fixed rules about the development of a baby born prematurely. Some progress faster, while others are slower. However, correcting for age in premature babies is a very helpful parameter.

Some of the problems a premature baby may have at birth will improve with time. Breathing, gastric or other difficulties usually disappear as they develop more.

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  • Grzona, M. E. (2006). Prematuros Extremos: ¿Es posible establecer un límite de viabilidad? Acta Bioethica, 12(1), 101-111.
  • Cabezas Arce, K. X. (2018). Estudio diferencial del desarrollo psicomotor de niños/as prematuros de entre 6 a 18 meses de edad con y sin otros factores de riesgo (Bachelor’s thesis, Quito: UCE).
  • Pierrehumbert, B., Borghini, A., Forcada-Guex, M., Muller-Nixe, C., & Ansermet, F. (2010). Niños nacidos prematuramente: una mirada atenta a los resultados cognitivos y conductuales. PsicoPatología, 9.