Growth of the Prematurely Born Child

A variety of factors can affect the growth of children born prematurely.  Growth is determined by a combination of heredity and nutrition, and can be influenced greatly by prenatal and postnatal circumstances. 

Catch-up Growth

Catch-up growth refers to an increased growth velocity which occurs following recovery from something that has prevented a child from growing normally.  Catch-up growth can occur following a period of illness and/or undernutrition.  Premature infants may be extremely ill for an extended period following birth and may experience undernutrition due to inadequate intake or poor absorption of nutrients during this time.  How much catch-up growth a child experiences is determined by multiple factors, including the length and severity of the illness, the age of the child at the time of the growth interruption, the quality of nutrition provided during the recovery period, and how well the child is able to utilize nutrition during recovery.

Growth Disruption Associated with Prematurity

When a child is born very prematurely, it is likely that the experience of early birth and related complications will result in some disruption of growth during the period of greatest illness.  Children who are also born "small for gestational age" (SGA) may have already experienced prenatal undernutrition.  Additional complications can interfere with how well an infant can utilize provided nutrition for an extended period after birth.  These complications include bronchopulmonary dysplasia (BPD), gastrointestinal problems, oral aversion, and neurological impairment of oral-motor skills.

Some prematurely born infants will experience severe growth problems as a result of multiple complications, while others will recover more quickly and make early "catch-up" gains.  Prompt identification of complicating factors is extremely important in minimizing negative impact on growth potential.  

Bronchopulmonary Dysplasia (BPD) and Growth

Bronchopulmonary Dysplasia is a condition of impaired lung function which occurs in infants who have required assisted ventilation neonatally.  An extended period of supplemental oxygen may be needed while the damaged lungs heal.  During the recovery period, infants with BPD utilize extra energy breathing and may require increased caloric intake to maintain a normal growth rate.  Further, medications required to treat a child's BPD may interfere with appetite and the increased effort of breathing during eating may result in the child foregoing completion of meals.  For these reasons, infants with BPD typically require formulas with increased calories per ounce.  For more detailed information on BPD and nutrition, see Nutrition and Bronchopulmonary Dysplasia, provided by the Children's Hospital of Eastern Ontario.

Gastrointestinal Problems

Gastrointestinal (GI) problems are fairly common among children born prematurely.  One of the most common is gastroesophageal reflux (GER).  While frequently benign, GER can become gastroesophageal reflux disease (GERD), a more severe form, which can result in very serious growth failure, breathing difficulties, and recurrent pneumonia.  The severity of GERD is not necessarily related to the amount of vomiting.  Infants who cry and arch their shoulders back after feeding and who refuse to eat or begin limiting their feedings should be evaluated for GER.

Persistent vomiting and/or diarrhea may also be symptoms of GI dysfunction.  When a child seems to be taking in an adequate amount of calories, yet fails to grow normally, the possibility of nutrition loss through vomiting or diarrhea should be considered.  The more severe complications of the GI tract should be evaluated by a Pediatric GI specialist and may also require consultation with a nutritionist experienced in  working with premature infants.

Oral Aversion

Prematurely born children may be at increased risk of having problems with oral aversion.  Some children become extremely sensitive to certain textures.  These sensitivities can interfere with food intake.  Some children never become entirely comfortable with bottle feeding, yet will later take food from a spoon without difficulty.  Others drink from a bottle easily, but refuse to progress to textured foods or hold food in their mouths rather than swallow.  Many children with oral aversion dramatically increase their tolerance of foods once they begin to develop the necessary fine motor skills to feed themselves finger foods.  Oral aversion can be successfully treated, but it can be a long, slow process, particularly after behavioral patterns become well-established.  A psychologist, speech therapist, or occupational therapist experienced in working with feeding disorders should be consulted as soon as a problem with oral aversion is suspected.  A thorough evaluation will be needed to establish the range of factors involved and to rule out unidentified physiological problems.

Neurological Impairment

Prematurely born children are at increased risk for a range of neurological problems, and neurological difficulties can contribute to feeding difficulties.  Children with cerebral palsy may have problems with oral-motor skills necessary for sucking, chewing, and/or swallowing, as well as gastrointestinal problems related to neuromuscular weakness.   Children who have sustained neurological injury (e.g., brain bleeds, lack of oxygen to the brain, etc.) may have similar problems during the recovery period, regardless of whether or not they eventually completely recover neurological functioning.  Children with low muscle tone may have particular difficulty with gastro-esophageal reflux (GER).  Children who have sustained neurological injury are also more likely to be especially sensitive to textures and may gag very easily when trying to swallow.  Very young or very ill infants may be likely to stop feeding before they are full because of the increased effort required when eating.  Close monitoring of growth parameters is particularly important and consideration of diet changes or alternative methods of feeding will be necessary if growth begins to decline markedly.

Psychological Factors

Fragile infants, recovering from very serious illnesses, can be very difficult to feed and difficult to "read."  Some prematurely born infants, even after they become healthy, still do not give clear cues to express hunger.  Children with lung disease, gastro-esophageal reflux, or other medical problems may tire before taking in enough nutrition in one feeding and may not seem interested in additional feedings.  It can require considerable hard work to provide the frequent, small feedings necessary to maintain adequate nutrition for infants who can consume only small amounts at a time.  While feeding time is the most pleasurable activity most young infants experience, it can be painful and stressful for infants experiencing feeding difficulties.  It also tends to be intensely stressful for parents.

Reducing the stress and anxiety surrounding feedings can help to increase food intake and facilitate digestion.  A psychologist or occupational therapist who specializes in infant feeding problems can provide consultation in situations where feeding difficulties are intense or prolonged.   Making the feeding experience as relaxed and enjoyable as possible for both the parent and child is an important first step toward increasing intake.

Summary

This page outlines some of the major causes of feeding and growth difficulties in prematurely born infants.  This list is not intended to be inclusive, but rather to give an idea of the range of contributing factors.  In most children who have significant growth failure (referred to medically as "failure-to-thrive"), multiple causes are involved.   Further, it is important to remember that behavioral components become important for any child who continues to have feeding problems over an extended period of time.  When feeding problems persist over more than a few weeks, the infant and parents can become caught up in a pattern of meal-time behaviors that can exacerbate existing physiological problems.  Parents of children with serious growth problems need the help of understanding professionals who will take the time to evaluate all aspects of this complex problem.  It is essential that parents and professionals work together to avoid misinterpreting the symptoms of underlying physiological problems.