Corrected age of premature infants: what is it and why should it be taken into account?

The corrected age of premature babies is basically used to assess whether the development of the baby born prematurely presents any deficiency. Also to establish feeding guidelines and school them at the right time.

Last update: April 14, 2022

The corrected age of premature infants is a very important piece of information, since on this depends the correct monitoring of its development. This applies, in particular, to the first two years of life, a critical stage.

The evolution of a child born prematurely is very different from that of one who was born at term. The development goals in each case are not achieved at the same time. Therefore, it is very important to take into account the corrected age of premature infants.

If the corrected age of premature infants is not available, unrealistic expectations may be formed in the face of the baby’s advances. Sometimes the diaper is even taken off or taken to school early, which ends up being negative for the little one.

What is the corrected age of premature infants?

The corrected age is the “real age” of the baby, starting from the date on which it should have been born.

To understand the concept of corrected age for premature infants, it is first necessary to be clear about what gestational age and chronological age are. In very simple terms, we can define them as follows:

  • Gestational age. It is the time that the gestation has lasted. It is counted by weeks, starting from the last day a woman had her period until the day she gave birth.
  • chronological age. It is the time that starts counting after birth. It is counted in days, weeks, months and years.

However, the corrected age of premature babies corresponds to the age the baby would have been if he had been born at 40 weeks, that is, at term. Based on this, a calculation is made in which the weeks that were missing to complete the 40 are subtracted and this indicates the “real” age of the child.

What is it for?

The corrected age of preterm infants is a crucial piece of information to assess development physical and neurological of the baby. In general, weight, height, and head circumference are assessed according to age. Each age corresponds to a normal range in each of these variables.

If the corrected age is not obtained, but rather the chronological age is used, there will be a gap. If the chronological age of the child is taken as a basis, that is, the time that has elapsed since he was born, the estimated weight, height and head circumference will be less than that of a child who was born at term.

Therefore, there will be an apparent anomaly, although it does not exist. Hence the importance of obtaining the corrected age of premature infants. This, in addition, offers a real parameter to know when complementary feeding should be introduced.

The corrected age of premature infants should be used until the child is 2 years old.. Premature babies have a slower development and, in addition, they could show some difficulties in reaching it. Still, it is normal for this to happen. After the age of 2, his evolution is the same as that of other children.

Calculation of the corrected age of premature infants

Calculating the corrected age of premature infants is very simple. You should only have two very clear data: the date of birth and how long the pregnancy lasted. In other words, gestational age and chronological age.



Posting must be done in weeks. What follows is to subtract the gestational age at 40 weeks, which corresponds to a full-term pregnancy.. If, for example, the baby was born in the 36th week, this figure must be subtracted from 40. The result would be 4.

The next step is: the chronological age must be subtracted from the previous result. If, for example, the child is 8 weeks old, that is, two months, the 4 that the previous step gave us as a result must be subtracted from that 8. Thus, the corrected age would be 4 weeks. Schematically, it would look like this:

Pregnancy age at term – Gestational age = x

Chronological age – x = Corrected age

Vaccines in premature babies

The only case in which the corrected age is not considered is at the time of administering the vaccines.

The corrected age of premature infants should be used for all purposes except one: vaccinations. These should be applied to him in the same way that they are applied to babies born at the correct term.

This is because premature babies are very vulnerable. to various types of infections due to immaturity in their development. For this reason, the World Health Organization (WHO) itself recommends vaccinating them taking into account their chronological age and not the corrected age.

It is very important to start vaccination at two months, unless the pediatrician indicates otherwise. The risk of infection by pneumococcus or influenza type B is higher in premature babies. It is even recommended that they receive the flu vaccine from 6 months, especially if they were born before 32 weeks of gestation.

The corrected age of premature infants is a guide

The corrected age of premature infants is used in particular to assess the psychomotor and physical development of the child. Also to establish when complementary feeding should be introduced in your regular diet.

Breastfeeding is recommended for the first six months of life.. Complementary feeding should not be introduced before four months, based on corrected age. The pediatrician will inform if it is necessary to make variations to these premises in particular cases.

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