How do you calculate corrected age? How long do you correct a child’s age who was born prematurely?
How long do we continue to correct for prematurity?
Why do we correct for prematurity when determining if a child is developing as he/she should?
When do premature babies “catch up"?
Will a child who was born prematurely always be physically small?
Do developmental evaluations in a child’s first three years of life tell us how she will do in school?
What is the difference between a DI/DQ (developmental index/quotient) and an IQ (intelligence quotient)?
Send your questions to Sheena.Carter@emory.edu.
|Calculating Corrected Age|
|Step 1:||Calculate your child’s age in months.
Year Month Day
1998 09 21 (today's date)
- 1997 06 03 (birthdate)
1 03 18 chronological age - 16 mos.
|Step 2.||Determine # of weeks your child
was born early.
40 weeks = term
- 27 weeks = gestational age
13 weeks = # of weeks born early
|Step 3:||Convert answer from step #2 to months
by dividing the number of weeks by 4, and convert any left
weeks to days.
13 weeks = 3 months 7 days
|Step 4:||Corrected age = subtract step #3
from chronological age in months
16 months Chronological Age 15 months 30 days
There is currently no consensus among professionals regarding correcting a child’s age for prematurity. Some developmental centers and researchers do not correct at all, while some recommend you correct into school age. The majority of professionals who work with prematurely born children correct through age two years. In our clinic we correct for the first three years. This is the age many of the children we serve go to pre-school and the school system will use their chronological age.
When having a pre-schooler evaluated you can always ask that test results be scored at both the child’s corrected and chronological ages. This will allow you to consider both. While age correction is most meaningful in the first year of life, a few months in age can continue to make a difference in what is expected of a child at least through pre-school.
A human being takes approximately 40 weeks, give or take two weeks (38-42 weeks), from the time of conception (the egg and the sperm meet) until the baby is fully developed. If an infant is born at or before 37 weeks s/he is called a premature infant. If s/he is born after 42 weeks it is considered a post term infant.
Preterm infants are at increased risk to suffer complications at birth and developmental problems as they get older. This is because the preterm infant's organs are not fully developed for survival outside the womb. The earlier the gestation (number of weeks from conception) the infant is born, the greater the risks for long term physical and developmental problems.
An infant's gestational age is determined by several sources of information. First, the woman can provide information about when she had her last menstrual period. An early ultrasound, one done in the first trimester, can closely estimate a baby's due date. A third commonly used method for figuring gestational age is a test called the Dubowitz, which is usually done within 48 hours of delivery. Certain physical signs indicate how developed the infant is, each physical sign noted is given points and the total is then converted into a gestational age for the infant. All these factors are taken into consideration in determining an infant's "true" gestational age.
Why is it important to determine gestational age? It helps the obstetricians and neonatologists anticipate what complications an infant might be expected to have. This can help them anticipate the infant's needs. Knowing the gestational age of your infant is also helpful for anticipating what you, as a parent, can expect your child to do at any given age. Some of a young infant's development is strongly influenced by his/her experiences. But much of a young infant's development is going to unfold as their body grows and develops in a set biological sequence. A two-month-old does not have the muscle strength or the neurological development to control his/her body in a sitting position. Around six months, give or take a month, the infant's body has matured enough to be able to accomplish this task. Parents of prematurely born infants need to know their child's gestational age (corrected age for prematurity) or they may worry needlessly when their baby is not sitting up on his/her six month birthday (chronological age). A baby who was born early may be six months from birth, but in terms of his/her corrected age may be only 3 months old. A child's nerves, brain and muscles do not leap forward in their development just because the child was born early. It is best to expect an infant to progress at the rate they would if the child had been born at term.
Some aspects of development are affected by experience; other aspects of development will unfold at the rate they would have if the child had been born at term. The central nervous system does not speed up its development just because a child was born early. Layered over both of these facts are the complications that some prematurely born children experience in the NICU. Some complications may have short term effects on development; some may have long term effects.
Early “catch-up” growth does occur for head circumference in the first few months post term. Some relatively late “catch-up” gains also do occur in growth for most children, though it is not usually possible to make predictions for a particular child.
Adult size is determined primarily by genetics and nutrition. If you are able to maintain adequate nutrition and health throughout childhood you will reach your genetically predetermined size. Nutrition and growth are very important issues for all children. If your child has no oral motor or gastrointestinal problems and was born at an appropriate size for gestation he should reach his genetically determined size. If your child was small for gestational age or intrauterine growth retarded (IUGR) the child may have lost some of his growth potential. This child will need his nutritional status and growth monitored closely. Likewise, some complications seen in prematurely born children may affect their growth, for example severe BPD or severe reflux which can result in oral aversion and subsequent inadequate nourishment.
Developmental evaluations tell us how well a child is developing for his or her age. Your child's test scores are compared to the average scores for children of the same age. The areas tested include:
- language skills - progress towards speaking and understanding speech.
- social behavior
- thinking/problem solving
- fine motor skills - eye-hand coordination
- gross motor skills - using large muscles for movement
The assessment should also take into consideration the quality of the child's performance. Were items completed on the first try or after many trials? Was the child's approach to working with the materials calm and focused, working with ease, or was the child frequently frustrated? Watching how a child responds during the test can assist us in understanding how the child may be helped most successfully.
The results from testing infants and young children do not let you know how she may do at school age or later in life. There are a number of reasons it is difficult to predict later levels of functioning from testing done with infants and young children. One of the reasons for this is that the most critical skills tested in older children and adults do not yet exist in infancy. A newborn, for example, must be assessed through how well he uses his eyes (visual system) and hearing (auditory system) to attend to his surroundings and notice change. As the child gets a little older a more accurate assessment can be obtained by trying to determine what a child knows through newly developing motor skills. The measurement of language, perhaps the most important skill evaluated in older children, provides little information in the first year of life.
Another reason infants tests cannot predict future success involves the importance of later events in determining a child's progress. A young child may have a sensory impairment or motor problem that would profoundly affect their performance and limit your access to what she knows. Later correction or adaptation for the impairment (e.g., glasses, hearing aids, braces, etc.) may provide a dramatic difference in the course of the child’s progress. In addition, we are still learning about the various ways children’s behavior relates to brain development. We are learning more about the brain, genes, the interplay with the environment and the young brain’s ability to recover from injury every year.
You may ask, “What is the point in having a young child evaluated?” Developmental problems tend to emerge slowly over time as higher levels of brain functioning are called into use. Injury to areas of the brain important for later functioning may not be apparent in an infant or very young child. It is important to look at high risk children frequently over time to identify delays in their development compared to age mates. Identifying delays early allows for investigation into causes and referral to therapies that may be able to improve or stabilize skills (keeping them from falling further behind). It is also helpful to compare a child’s current performance to their previous pattern of development. This allows consideration of the rate of change and recovery being made.
The average child’s IQ is not stable until around four years of age. It may be much later in children who were born early or who have significant health issues.
DI, DQ, and IQ each refer to standard scores that are used to compare a child’s functioning to that of a normative group. That is, they compare your child’s performance to the “average” performance of a large group of children of the same age. For each of these scores, the average (mean) is 100 with a standard deviation of 15 points. Over 95% of children in the population on which the test is based are expected to score between 70 and 130, inclusively, on these standardized tests.
IQ is an abbreviation for Intelligence Quotient. “Intelligence,” as measured by IQ tests is rather narrowly defined. An IQ is intended as a predictor of the level of abilities a child will need to be successful in school. In the general population this score becomes relatively stable after about four years of age. Children with higher IQs are expected to perform better academically; whereas, low IQs predict academic difficulty. Children with IQs below 70 usually qualify for special educational assistance. An IQ below 70 is part of most accepted definitions of Mental Retardation. (Note: In addition to mental retardation, there are many other reasons that a child may score below 70 on an IQ test.)
Results for developmental tests on an infant or very young child may be reported as a Developmental Quotient (DQ) or Developmental Index (DI). Like an IQ, the DQ or DI refers to how well a child performs on a standard set of tasks as compared with a normative sample of children the same age. Because developmental tests in infancy do not measure the same functions that later IQ tests measure, and because a child’s overall performance relative to peers may be very different in later childhood than in infancy, a DQ or DI should not be considered as an early indication of how well a child may perform on later IQ tests. The results from any test of infant development are useful only as an indication of current functioning.