When the growth of a low-birth-weight (LBW) infant is evaluated, the gestational age should be considered. Growth parameters should be plotted on growth curves that have been developed using low-birth-weight preterm infants exclusively (5). Measurements should be plotted according to the infant’s adjusted age until approximately 2.5 years of age, when the age difference becomes insignificant. Various patterns of growth emerge from different groups of patients.

Healthy, LBW, appropriate-for-gestational-age (AGA) infants generally experience catch-up growth during the first 2 years of life, with maximal growth rates between 36 and 40 weeks of gestational age. Little catch-up growth occurs after 3 years of age. Head circumference usually is the first parameter to demonstrate catch-up growth and often plots at a higher percentile than do weight and length. Increases in weight are followed within several weeks by increases in length. Rapid catch-up head growth must be distinguished from pathologic growth associated with hydrocephalus. An imaging study may be indicated if the infant’s history or symptoms suggest hydrocephalus. Insufficient brain growth, a head circumference falling more than two standard deviations below the mean, indicates that the infant is at risk for significant developmental disability.

Growth velocities for weight and height vary considerably. Some preterm infants show growth on curves between the 75th and 97th percentiles by 3 months adjusted age, whereas others remain on low curves well beyond the child’s first year. It is helpful to evaluate an infant’s weight gain in comparison to gains in length. Low weight for length or a decline in all growth parameters suggests inadequate
nutrition. Weight percentiles significantly greater than length percentiles indicate obesity. Obesity may occur in a preterm infant whose parents overfeed their previously underweight baby. It is common to see an infant who was formerly failing to thrive rather abruptly become obese when the medical problems resolve but the diet remains high in calories.

Growth of the small-for-gestational-age (SGA) infant is influenced strongly by the cause of the intrauterine growth retardation. Overall, LBW-SGA infants demonstrate less catch-up growth than LBW-AGA infants, but if they do, acceleration starts by 8 to 12 months of adjusted age (2). Approximately 50% of LBW-SGA infants are below average in weight at 3 years of age, whereas only 15% of LBW-AGA infants remain below average weight at the same age (4). Symmetric SGA infants with birth head circumference similar in percentile to birth weight are less likely to demonstrate catch-up growth than are those asymmetric SGA infants whose birth head circumference was at a significantly higher percentile than their weight. As with AGA infants, head circumference is normally the first parameter to demonstrate catch-up, followed by weight and then by length.

Because of the wide range of growth that is considered normal during the first several years of life, it is best to analyze trends in growth rather than make assumptions based on single measurements. When abnormalities are noted in growth trends, investigation of the infant’s nutritional status during hospitalization, the results of cranial sonography studies, and the status of continuing illnesses should be undertaken to identify a possible cause.

Traditionally, although somewhat controversial, the goal for preterm infants is to achieve a growth rate approximating that expected while in utero had they not been born prematurely (4). Because weight gain is suboptimal during acute illness, all efforts should be made to promote catch-up growth once the medical condition is stable. The nutritional needs of the preterm infant during the first few months of life exceed those of a term neonate and may continue for the entire first year of life even if there are no exceptional medical or feeding problems. Appropriate choices for many preterm infants include breast milk and routine infant formulas, but because many preterm infants continue to have increased caloric requirements, breast milk and routine formulas often need to be supplemented with either carbohydrates or fats. Formulas can be concentrated somewhat to increase their caloric density, allowing the infant to consume more calories per unit volume. There are now commercially available premature growth formulas tailored to address the unique protein, fat and caloric needs of the growing preterm infant for the first year of life (6,7,8). Most infants do not tolerate feedings with caloric densities greater than 30 kcal/oz. Infants given feedings concentrated beyond 24 kcal/oz should be monitored for symptoms of intolerance such as vomiting and diarrhea and for hyperosmolar dehydration secondary to insufficient free water intake. Whole cow’s milk is poorly tolerated and should be avoided. When caloric additives or concentrated formulas are used, care should be taken to maintain an appropriate caloric distribution of nutrients with a ratio among carbohydrates-fats-protein of approximately 40-50-10 (6).

Caloric requirements for adequate growth vary. Healthy preterm infants generally require 110 to 130 kcal/kg per day, but some infants with chronic disease may require up to 150 kcal/kg per day (9). Caloric intake should be increased as tolerated until weight gain is satisfactory.

Often infants with ongoing illness or those just recovering from their long hospitalization will be unable to consume the volume of formula or breast milk needed to provide them with the calories they need for catch-up or even maintenance of their ideal growth rate. It is not uncommon to suggest offering up to one-half of their daily calculated needs by continuous feedings (by tube) through the night and allowing them to feed the remainder orally during the day. Taking that approach often decreases the need to consume large volumes by oral feeding and allows the infant to increase volumes as tolerated during the day, after which nighttime volumes can begin to be decreased.

The American Academy of Pediatrics (AAP) recommends that full doses of DtaP vaccine be administered to prematurely born infants at the appropriate postnatal i.e., chronologic age. A large percentage of preterm infants demonstrate inadequate protection if given a reduced dosage of DTaP vaccine at the routine intervals. Fewer side effects occur in preterm infants who receive full-dose vaccine than in their full-term counterparts, and the use of acellular pertussis vaccine should obviate any concerns in this regard. The same contraindications to immunizing full-term infants against pertussis apply to preterm infants. Most importantly, infants with bronchopulmonary dysplasia (BPD) are at highest risk for serious sequelae if they contract pertussis. Therefore, the pertussis component of this vaccine should not be withheld. Similarly, the pertussis component should also be given to any child with cerebral palsy or other muscle tone abnormalities. If an infant has an underlying seizure disorder, the decision to withhold pertussis should be reviewed with the individual’s neurologist.

The AAP Committee on Immunization Practices recommends that full-dose inactivated, enhanced potency polio (IPV), haemophilus influenzae type b (Hib), pneumococcal, varicella, and measles-mumps-rubella (MMR) vaccines be administered at the appropriate chronologic age.

Infants with chronic pulmonary disease (e.g., BPD) or cardiac disease with pulmonary vascular congestion are at high risk for the development of serious illness if infected with an influenza virus (14). Infants with influenza have presented with symptoms of sepsis, apnea, and lower airways disease. To protect vulnerable infants, immunization with influenza vaccine is indicated for household contacts, including siblings, primary caretakers, and home care nurses and hospital personnel. For infants older than 6 months chronological age, two doses of split virus vaccine should be given 1 month apart between October and December, followed by an annual dose. It is now recommended that influenza vaccine be given to all infants under 2 years of age (13,14). Older siblings under 9 years of age who have not received previous influenza vaccines also require two doses initially. However, adults and older siblings with natural immunity or who have received previous immunizations need only one yearly dose.

Preterm infants, especially those with underlying chronic lung disease, are particularly at high risk for serious sequelae after becoming infected with respiratory syncytial virus (RSV) during the late fall and winter months. Many will require re-hospitalization and re-intubation for respiratory failure and are often left with worsening lung disease requiring increased support with supplemental oxygen, bronchodilators, or and/or diuretics. Attempts at developing a vaccine to protect against RSV have been unsuccessful; however, an anti-RSV monoclonal antibody (Synagis^®) has been approved for use in high-risk infants (15,16). Monthly intramuscular injections are necessary to provide passive protection throughout the RSV season. Synagis^® is expensive; thus, its use should be limited to those infants most at risk. According to the guidelines set forth by the AAP (14), those who should be considered to receive monthly injections include the following:

For infants with birth weights below 2,000 g born to hepatitis B surface antigen-negative women, it is advised to delay the initiation of hepatitis B vaccine until just before initial hospital discharge, provided the infant weighs more than 2,000 g or until 2 months of age when other immunizations are given (13).

Retinopathy of prematurity (ROP) (see Chapter 54) is a disorder that interrupts the normal vascularization of the developing retina. Although it has been reported in term infants, ROP is mainly a disease associated with prematurity and, in particular, with those less than 32 weeks gestation. The incidence and severity of ROP increase with decreasing gestational age. Most cases of ROP resolve spontaneously, but even with complete resolution, scarring of the retina may occur. Generally, the more severe the disease, the longer it takes for resolution. An infant with ROP affecting Zone 1, however, is at a much greater risk for permanent visual sequelae than one who has the disease affecting Zone 2 or 3 (17,18). According to recommendations in the AAP Guidelines for Perinatal Care (19), infants with a birth weight of less than 1,500 g or with a gestational age of 28 weeks or less, and selected infants between 1,500 and 2,000 g with an unstable clinical course who are believed to be at high risk by their attending pediatrician or neonatologist should have an ophthalmologic examination for ROP. The initial examination should not take place before 4 to 6 weeks chronologic age or, alternatively, within the 31st to 33rd week of postconceptional age, whichever is later. Prior to this, the yield for identifying ROP is low. If only one examination is possible, it should be at 7 to 9 weeks of age to catch the peak period of occurrence. A schedule of follow-up visits is based on the retinal findings and should be determined by the examining ophthalmologist. All infants with immature fundi or any stage of ROP require close monitoring until the eyes have matured or the ROP has completely resolved. Thereafter, follow-up to assess for refractive errors should be at 1 year of age and before kindergarten, or earlier for any clinical concerns. Infants with resolving (incompletely resolved) ROP need careful follow-up because some revert to active disease.

Sequelae of ROP depend largely on the extent of retinal scarring. As much as 80% of stage 3 ROP resolves spontaneously without significant scarring, but, even in infants with fully regressed ROP, there may be subtle retinal changes resulting in refractive errors, strabismus, or amblyopia. Additionally, an infant left with moderate scarring can experience retinal tears, late retinal detachment, nystagmus, glaucoma, cataracts, vitreous hemorrhage or membranes, and severe scarring that can lead to blindness (19). Services for visually impaired children are available on county and state levels. Early identification of a child with visual handicaps to such programs is essential to provide the child and family with the services and resources they need.

The incidence of sensorineural hearing loss in preterm infants is generally reported to be between 1% and 3%. Several factors place these infants at particular risk for hearing loss, including hypoxia, hyperbilirubinemia, infections, unstable blood pressure, environmental noise, and ototoxic drugs. According to the Joint Committee on Infant Hearing, Year 1999 Position Statement where the Universal Newborn Hearing Screening (UNHS) Program is described, all infants should have access to hearing screening using a physiologic measure before hospital discharge or have access to and be referred for screening before one month of age (20). However, all newborns or infants who require neonatal intensive care should receive hearing screening before discharge from the hospital. All infants who do not pass the initial screen or any subsequent re-screening should begin appropriate audiologic and medical evaluations to confirm the presence of hearing loss before 3 months of age. All infants with confirmed permanent hearing loss should receive services before 6 months of age in interdisciplinary intervention programs that recognize and build on strengths, informed choice, traditions, and cultural beliefs of the family. All infants who pass newborn hearing screening but who have risk indicators for other auditory disorders and/or speech and language delay should receive ongoing audiologic and medical surveillance and monitoring for communication development. Infants with indicators associated with late-onset, progressive, or fluctuating hearing loss and auditory neural conduction disorders and/or brainstem auditory pathway dysfunction should be monitored.

Depending on the screening technology selected, infants with hearing loss less than 30 dB or with hearing
loss related to auditory neuropathy or neural conduction disorders may not be detected in a universal newborn hearing screening program.

All infants, regardless of newborn hearing screening outcome, should receive ongoing monitoring for development of age-appropriate auditory behaviors and communication skills. Passing an initial hearing screening does not preclude the possibility of a later, acquired hearing loss. Absent or abnormal responses to auditory stimulation, delays in speech development, poor articulation, or inattentiveness should raise the suspicion of a hearing loss that requires a more thorough evaluation. All infants who do not pass an initial hearing screen should be referred to an audiologist for further testing and intervention. In general, an infant with a sensorineural hearing loss should have a repeat audiologic evaluation performed every 3 months for 1 year after initial diagnosis, every 6 months during the preschool period, and yearly while in school.

In hearing tests, zero-decibel (dB) represents the level at which response to a sound should occur 50% of the time. If sound is not heard at this level, the decibel level is raised until the sound is audible 50% of the time. Responses above 15 dB are indicative of some degree of hearing loss (Table 59-1).

Children with moderate to profound hearing loss are at high risk for delayed onset of language, problems with articulation, language impairment, and alterations in voice quality. Cognitive delays may be encountered as a result of a loss of auditory input or a language delay. Behavior problems often are experienced and include inattentiveness, overactive or aggressive behaviors, and immature peer relations.

Hearing aids can be fitted early in infancy to avoid acoustic deprivation. With auditory stimulation being provided, language acquisition may proceed more normally. Along with hearing amplification, language stimulation therapy (sign language) should be provided.

For those children whose hearing loss cannot be improved by hearing aids, different modes of communication are necessary. These include sign language, alternate methods of gesturing or word spelling, language boards, or computer-assisted communication devices. The latter two methods are particularly useful for a child who is limited motorically as a result of cerebral palsy.