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Assessment of infant growth
n
Assessment of Infant Growth Belinda
J. Pinyerd,
n
PhD, MS, BSN
Growth is one of the best indicators of neonatal and infant well being. By comparing the growth of an individual infant over a period of time with available standards, the determination can be made, within limitations, whether the infant is doing as well as should be expected or whether any growth abnormalities exist. The three most common physical measurements of growth are weight, length/ height, and head circumference. Normal growth patterns and factors that impact growth within the first 2 years of life are discussed, with recommended techniques for assessment. J PEDIATR HEALTH CARE. (1992). 6, 302-308.
I
n pediatrics, the termsgrowth and development are often used interchangeably, but in a strict sense they are not synonymous. refers to proportionate changes in size; developmat refers to increasing complexity (Krogman, 1972). This article addresses fetal and infant growth through the first 2 years of life. Assessment of growth in infants is based primarily on weight measurements, given the accuracy and ease in making reliable determinations. As a single criterion of growth, however, measurement of length is a better criterion than is the measurement of weight. The third component of physical growth, specifically brain growth, is the head circumference. This article addresses these three components of physical growth in the fetus and the infant under 2 years of age, including normal and abnormal growth patterns, techniques for evaluation of growth, and factors affecting growth at the various stages of development.
G m vth
H NORMAL AND ABNORMAL GROWTH PATTERNS
Each developmental stage is characterized by patterns of growth that can be generally quantified, although wide intraindividual variability exists as a function of genetic, hormonal, nutritional, and environmental influences. Given that each child has an individual growth pattern, typical or average values for height and weight should be considered only points of reference. When sequential measurements are obtained, the percentile method of recording height and’weight is much more useful than tables stating means and standard deviations (Lowrey, 1986). This section categorizes the
Belinda j. Pinyerd, PhD, MS, BSN, is the Assistant Director of the Clinical Study Center and a nurse researcher in the Department of Nursing at Children’s Hospital in Columbus, Ohio. Reprint requests: Belinda 1. Pinyerd, PhD, MS, BSN, Clinical Study Center, Children’s Hospital, 700 Children’s Dr., Columbus, OH 43205. 25/o/40009
302
normal growth patterns across four developmental periods: intrauterine (conception to birth), neonatal (birth to 28 days), infant (1 to 12 months), and toddler (12 to 24 months). Intrauterine
(Conception
to Birth)
Intrauterine growth begins with conception and ends with birth. Although these are separate periods, fetal and neonatal growth are actually one continuous process, with birth and the beginning of extrauterine existence simply marking an important dividing point (Lowrey, 1986). The growth rate of the human fetus is determined by the number of cells that are present and their rate of division. Unfortunately, the precise mechanisms behind the regulation of cell division are unknown. Mer the period of major organogenesis, the fetus enters a period of incremental linear growth, achieving the greatest velocity at mid-fetal life (4 months). With the development of adipose tissue at about 7 months of gestation, an acceleration occurs in weight gain, with the weight doubling during the last 2 months in utero. At this stage, the fetus fills the uterine cavity to the extent that the uterine size becomes a constraining factor in late fetal growth. In terms of length, beginning with gestational week 25 the fetus grows 0.40 inches (1.0 cm) weekly. Peak lengthening, 0.54 inches (1.3 cm) weekly, occurs between 31 and 34 weeks. After that, growth velocity diminishes, and at 40 weeks the incremental rate is 0.20 inches (0.5 cm) per week (Korones, 1986). Some gender differences are apparent because the male fetus grows faster than the female fetus, predominantly after 32 weeks gestation. In both sexes, prenatal growth of the head is linear beginning with the latter half of pregnancy to about 32 weeks. At the maximal growth rates between 30 and 32 weeks, head circumference increases by 1.2 m m daily. Daily increments then diminish gradually, and at 40 weeks the rate of growth subsides to 0.2 m m daily. JOURNAL
OF PEDIATRIC
HEALTH
CARE
Journal of Pediatric Health
Neonate
Assessment
Care
(Birth
to 28 Days)
The average birth length in North America is about 20 inches (50 cm), and the mean birth weight is usually between 7.0 to 7.5 pounds (3.0 to 3.4 kg) (Lowrey, 1986). Birth length does not correlate well with midparental height (the mean height of the parents), the size of the father (Morton, 1955), or to the height of the same individual at maturity (Tanner, Healy, Lockhart, Mackenzie, & Whitehouse, 1956). Instead, birth length correlates best to the size of the mother only (Polani, 1974). Some gender differences have been noted in terms of physical growth. The newborn male averages 0.35 inches (0.9 cm) longer, is 150 gm heavier, and has a greater head circumference at full-term than the newborn female (Babson, Behrman, & Lessel, 1970). Male newborn babies also are slightly more muscular and less obese than female newborn babies (Tanner, 1974), possibly a consequence of elevated testosterone levels in the male fetus (Smith, 1977). Infant
(1 to 12 Months)
After birth, the infant shifts from a growth rate that is predominantly determined by maternal factors to one that is increasingly related to the infant’s genetic background and other physiologic factors. The first postnatal year is perhaps the most important single growth period of all (Krogman, 1972). Although individual growth rates are rapid and highly variable during the first year, the general rule of thumb is that birth weight trebles, birth length doubles, and birth head circumference increases by one third. Some infants exhibit delayed or accelerated growth rates as they compensate for or “adjust to” a constitutional percentile that is genetically driven. For example, small-for-gestational age neonates whose genetic background indicates larger size may grow somewhat more rapidly in the first 12 to 18 months than normal-weight neonates (Amer, August, & Robnett, 1992). Thus, newborns who are small for gestational age and who have the genetic capacity to “catch up” to the normal range generally will show accelerated growth within the first 6 months after birth. In contrast, most small-forgestational age babies who do not show catch-up growth during the first 6 months continue to grow at a slow rate into childhood and are generally destined to be of small stature (Fitzhardinge & Steven, 1972). Finally, those who are relatively large at birth but whose genetic background is for smaller size tend to maintain the prenatal growth rate for several months before beginning their deceleration into a lower growth channel (Smith et al., 1976). The postnatal pattern for linear growth returns to the pattern that existed in utero at 32 gestational weeks.
of Infant Growth
303
An infant’s height will increase approximately 1 inch per month in the first 6 months, and then gains will decrease to 0.5 inch per month in the second 6 months. By the end of the first year, the infant will increase in length approximately 50% and in weight by 150%. Toward the latter half of the first year, a gradual diminution in growth rate will occur, accompanied by a reduction in the degree of adiposity. During the first 6 months, the average baby gains close to 2.2 pounds (1 kg) per month, or nearly 1 ounce (30 gm) per day. Over the next 6 months the average increase is 1 pound per month. More than one half of healthy infants will have doubled their birth weight within 3 to 4 months, tripled it by 12 months, and quadrupled it by the end of the second year. Generally, weight gain is slightly greater in formula-fed infants as compared with breast-fed infants. Brain growth is particularly important given the fact that many aspects of human development are dependent on and occur as a result of brain development (Holt, 1991). The practitioner’s most useful guide to brain growth is measurement of the head circumference. At birth, the average head circumference is 13 to 14 inches (33 to 35 cm), which is about one half its adult size. Head circumference reaches 18 to 19 inches by 1 year of age. Postnatally, head circumference grows 1.1 m m daily (or 0.5 inches/month during the first 4 months), which is close to the intrauterine pace that existed before the slowing of growth at 32 weeks (Korones, 1986; Lowrey, 1986). Growth returns to the rate that existed in utero at 32 gestational weeks, increasing rapidly to about 75% of adult size by 18 months, and 90% by 4 years of age. Proportionally, the circumference of the head at birth is typically larger than the chest circumference, which is 12 to 13 inches (30 to 33 cm), but by 2 years of age the chest measurement is larger than that of the head. Head circumference is a measurement that has a relatively narrow range for any age group, with a standard deviation that remains small and nearly constant for the entire growing period. Almost no variation is due to racial, national, or geographic factors (Nellhaus, 1968). However, head circumference varies significantly as a function of body weight. Therefore, allowance should be made if the infant is much smaller or bigger than expected for the age (Illingworth & Lutz, 1965). Holt (1991) offers the following as a useful working rule: 1. Babies under 6 months of age: allow 0.50 inches (1.3 cm) in the head circumference for each 2.2 pounds (1 kg) deviation of body weight from the mean. 2. Babies aged 6 to 12 months: allow 0.40 inches (1.0 cm) in the head circumference for each 2.2 pounds (1 kg) deviation of body weight from the mean. Two other head measurements used for assessment
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predictions are ofien made basedon the following “rule of thumb” (Krogman, 1972):
BOYS: BIRTH TO 36 MONTHS PHYSICAL GROWTH NCHS PERCENTILES NAME
6, Number
September-October
RECORD#
Boys: 2 x height 5 x weight Girls: 2 x height 5 x weight
at age 2 years = adult height at age 2 = adult weight at 1% years = adult height at 1% years = adult weight
During the second year of life, growth rates begin to decline so that by the end of the third year, the child’s growth rate has settled into a steady, consistent pattern that will persist throughout childhood. Between 18 to 24 months the child grows at a fairly consistent rate of 2 to 3 inches (5 to 7.5 cm) yearly. During the second year, the averagemonthly weight increaseis about 0.5 pounds (0.25 kg), with the rate of gain steadily decreasing. After age 2 years, the approximate annual increase in weight will be 5 pounds (2.3 kg) until the child begins the adolescent growth spurt. The major period of brain growth is over, with the brain achieving 90% of its adult size by 4 years of age. As a consequence of this early, rapid brain growth, dramatic changescan be seen in the proportion of the head to the body. Unlike the brain, the rest of the body has a prolonged growth period. The limbs, for example, grow faster than the trunk from early fetal life until at least midadolescence. The trunk constitutes 75% of body mass in the infant and 67% in the child. Also of significance is that growth occurs earlier in the distal part of the leg than in the proximal segment. The foot of a 1X-year-old is one half of its adult size as compared with the femur, which does not achieve one half of its adult size until the child is 4 years of age. FIGURE 1 National
Center for Health Statistics chart for infant boys (a separate chart is available for tracking growth in infant girls). Reprinted by permission of Ross Laboratories, Columbus, OH 43216. n
purposes are the occipitofrontal and fontanelle diameters. Cranial bones and fontanelles fuse at predictable times during infancy, allowing for normal growth of brain tissue. The occipitofrontal range for full-term infants is 4.1 inches (10.5 cm) to 5.1 inches (13 cm). Molding, which occurs during labor, createsmuch variation that tends to invalidate the use of this method in the early neonatal period. At age 1 year, the mean diameter is 6.3 inches (16 cm), and at age 2 the mean diameter is 6.7 inches (17 cm). Unfortunately, fontanelle measurement is not practical given the wide variability in size and shape. Toddler (12 to 24 Months)
Childhood has been referred to as “the era of stable growth” (Smith, 1977). At age 24 months, adult size
n
EVALUATION
OF GROWTH
The keys to monitoring a child’s growth are accurate and consistent measurementsof length/height, weight, and head circumference. When a child is evaluated in a clinic setting the most common reason for an unexpected deviation in measurement is an error in technique. Hence, measurements should be repeated, recorded, and plotted immediately to reduce the chance of error. Growth rate and growth velocity measurements are plotted on standardized charts to allow for comparison of an individual child’s values with a statistical norm. Length is usually recorded from birth until the child is 2 to 3 years of age (Lowrey, 1986; Tanner, 1990) and should be plotted on a standard growth chart for infants 1 to 36 months of age (Figure 1). Two people are usually needed (one can be the parent) to measure an infant properly. The infant is measured nude in the supine position with the knee gently held flat and the head firmly held with the lower border of the orbit in the same vertical plane as the external auditory canal.
Journal of Pediatric Health Care
Assessment of Infant Growth
305
\ Gently Press Knees Down Moveable Baseboard
Gently Hdld Head in Position
n FIGURE 2 Infant length measurement on a measuring table.
The distance between a right-angle device held against the head and a right-angle device held against the base of the vertical foot is measured. Neonatometers and infantometers have been developedfor determining the length of neonates and infants, respectively, and are strongly recommended (Figure 2). Length should be assessedthree times in the first 6 months of life and then every 3 months until the child is age2 years.Height velocity calculations basedon lessthan 6-month assessment intervals should be interpreted with caution in view of the natural seasonalvariability and the expected technique error that have been reported (Pinyerd, Zipf, Horswill, & Hayes, 1992). Standing height is most commonly performed when the child is between 2 to 3 yearsof age. The first standing measurement also should include a separatemeasurement of length for comparison. Becauseof the body position, the standing height measurementtends to be slightly shorter than the supine length measurement. For recommended technique in the child 2 to 3 years of age, see the article by Henry in this supplement. Body weight should be measuredwith beam or balance scalesthat can be read to 0.2 pounds (0.1 kg) and go as high as 33 pounds (15 kg) and should be plotted on the growth chart (Figure 1). Calibrated or standard weights should be availableto check the accuracyof the scalesone to two times per year. Measurementsshould be made with the infant either unclothed or wearing a dry diaper. Whichever technique is preferred, it should be used consistently across all infants at all times. As with height determinations, weight measurement should be recorded and plotted immediatelyon all routine and acute care visits. When a problem is suspected, weight should be assessedevery 2 to 3 weeks with the same technique and the same examiner if possible. Head circumference is measuredwith a nonstretchable tape firmly placedfrom the maximal occipital prominence around to the areajust above the eyebrow (Fig-
n
FIGURE 3 Head circumference
measurement.
ure 3). Measuring the head circumferenceis often easier if the measurementis taken from behind the infant, with the infant seated on an adult’s lap. The head circumference measurement should be repeated after completely removing the tape from the head to ensure accuracy. Keep in mind that thick hair, braids, or big ears can get in the way when measuring head circumference, leading to falsely high measurements.For example, 1 mm of scalp-hair thickness increasesthe total circumference by approximately 6 mm. Fortunately, the most critical period for following head growth is during the first 2 years, when scalp-hair thickness is less of a confounding problem. n
FACTORS AFFECTING GROWTH
PATTERNS
Normal growth from infancy through adolescencedepends on adequatenutrition (in both quantity and quality of caloriesingested), normal endocrine function, absence of chronic disease, normal genetic make-up, and a normal emotional environment. A variety of fetal, infant, environmental, and maternal factors can interact to retard intrauterine and postnatal growth (Box). Growth failure can be classified as being either primary or secondary. In primary prenatal-onsetgrowth deficiency, the skeletal cells’capacity for growth is affected, resulting in growth deficiency. Most of these disorders are either chromosomal abnormalities or mutant gene disorders within the fetus (Smith, 1977). O ther primary factors that may affect fetal growth include maternal intrauterine infection or normal-heredity small stature. To date, no effective mode of therapy existsto increasethe stature of children with primary cellular growth deficiency (Smith, 1977).
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Volume 6, Number September-October
Pinyerd
n &OX
CAUSES AND lNFANT
OF FETAL, NKINATAL, GROWTtl FAWJRE
Envirotpmental Ethnic Race Socioeconomic status Geographic location Deprivation syndrome
Congenital anomalies Chromosomal defects Multiple gestation
Infant
Maternal
Nutritional Inadequate intake Malabsorption Partial obstruction Mental deficiency Cardiac defect Respiratory insufficiency Renal dysfunction Hypothyroidism Metabolic disorders Pituitary growth hormone deficiency Chronic serious infection
Small stature Primiparity Grand multiparity Low prepregnancy weight Young maternal age Smoking Ethanol intake Heroin addiction Hypertension Renal disease Heart disease Syphilis Cytomegalovirus Rubella Toxemia
Secondary growth deficiency occurs as a result of an extrinsic causeoutside the skeletal system, most typically the mother. One type of secondary deficiency entails diminution of maternal support prenatally to a fetus that otherwise would have been normal (Korones, 1986). This deficiency is generally mild in infants born of mothers with malnutrition, toxemia, hypertensive kidney disease,heart disease,moderate ethanol intake, or heavy cigarette smoke ingestion. Weight is affected more than length, without obvious malproportion or anomalies. Most infants show catch-up growth, but overall postnatal growth is variable. Infants with more severeprenatal growth deficiency, however, may not show appreciable catch-up growth. Intrauterine growth retardation (IUGR) is a clinical term defining in utero growth failure as a result of prenatal insult (Cowett & Stern, 1985). These infants, differentiated by having failed to achieve normal expected growth, are clustered on the growth charts at the lower end of the spectrum for weight and length at their gestational age. Secondarypostnatal-onset growth failure occurs after birth but, again, originates in a problem outside of the skeletal system, either in the delivery of nutrients, hormones, or oxygen to the cells. Examples of problems that may result in growth failure include inadequate
5, Part 2 1992
nutrient intake, intestinal obstruction, malabsorption, emotional and/or physical deprivation, mental deficiency, heart defect, respiratory insufliciency, renal dysfunction, hypothyroidism, and metabolic disorders such as glycogen storage disease. Once specific therapy is aimed at correcting the causeof growth failure, dramatic catch-up growth can occur, depending on the age of onset, the duration, and the nature of the original growth problem (Smith, 1977). Of all the factors that affect growth, several warrant further discussion, given their dramatic affects. Smoking
The woman who smokes produces a small-sized infant. Fortunately, smoking cessation before the third trimester can ameliorate the effect of smoking on fetal weight (Zabriski, 1963). Th eref ore, the health-carepractitioner should expend extra effort with newly pregnant women who smoke to get them to break the habit before the sixth month of pregnancy. Alcohol
Infants born with fetal alcohol syndrome exhibit an altered pattern of growth and morphogenesis that include prenatal and postnatal growth deficiencies in height and weight. Few of these infants exhibit the usual neonatal catch-up growth observed in small-for-gestational age newborns. Infants with fetal alcohol syndrome remain growth-deficient throughout childhood; most remain more than two standard deviations below the mean for age in both height and weight (Fisher, 1985). Drugs
Exposure of the fetus to illicit drugs such as marijuana, cocaine, and heroin is often associatedwith IUGR and prematurity. Recent studies have shown that maternal cocaine use is related to decreasedbirth weight, head circumference, and birth length (Kelley, Walsh, & Thompson, 1991; Zuckerman et al., 1989). Furthermore, cocaine-exposedinfants may be at increased risk for inadequate gains in weight and height during the first 2 years of life (Kelley, Walsh, & Thompson, 1991). Maternal
Nutrition
During pregnancy, the expectant mother’s requirements for all nutrients increase. Obviously, a balanced diet basedon a variety of foods is the best way to ensure an adequateintake of all the nutrients. Unless the mother’s nutrition is very poor, the fetus is able to obtain adequate nutrition for prenatal growth, even at the expense of depleting the mother (Smith, 1977). Severe malnutrition during the period of most rapid brain growth is associatedwith permanent reduction in the total num-
Journal of Pediatric Health Care
ber of fetal brain cells. In humans, this critical period probably begins at about 15 gestational weeks and ends between 8 to 15 months after term. Continuous severe malnutrition during this period can result in permanent effects on brain size, composition, number of cells, and the production of glia and myelination, which may be critical for intellectual functioning (Evans, Bowie, Hansen, Moodie, & van der Spuy, 1980). Infant Nutrition
Growth is the single most valuable indicator of nutritional status and generalhealth in childhood (Waterlow et al., 1977) becausethe rate of change in stature (that is, growth velocity) is sensitive to nutritional deprivation. Not surprisingly given the strides in growth that occur during the first year of life, the nutritional needs are the greatest at this time. The energy requirements for a healthy infant during the first 6 months average 115 kcal/kg/day and gradually decrease to 105 kcallkglday by the end of the first year. During the secondyear, 100 kcal/kg/day provide sufficient energy for growth (Food and Agriculture Organization of the United Nations/World Health Organization, 1980). Breast milk and most formulas provide the major source of calories during the first 6 months, each having approximately 20 kcal/ounce. The appropriate distribution of calories into proteins, lipids, and carbohydrates is essential.Most of the dietary requirementscan be met by breast milk or formula during the first 6 months of life. During the second 6 months of life, the infant’s diet consists of breast milk or formula, mixed feedings, and increasedamounts of table foods. Cereal should be fortified with iron. O ther vitamin and mineral supplements usually are not required, although the diet must include an adequate source of vitamin C. During the toddler years,little basis exists for routine vitamin and mineral supplementation in normal children (Forbes & Woodruff, 1985). One mineral that warrants mention is iron. Iron deficiency anemia (IDA) remains the most common nutritional deficiency in North America. The infant between 6 and 12 months of age is particularly vulnerable in terms of long-term deficits in mental and motor development (Lozoff, 1990). IDA could develop in infar& fed cow milk before 12 months of age. bespite being advised against it, many parents introduce cow milk early becauseof its convenience and lower cost compared with infant formulas. Cow milk is a poor source of iron and, when introduced before the infant is 1 year of age, can causeintestinal blood loss. Fortunately, IDA is easily prevented. Breast milk alone gives most infants all the iron needed during the first 4 months of life. When the infant is premature or
Assessment
of Infant Growth
307
anemic, however, iron stores are depleted earlier, so earlier supplementation is warranted. After 4 months, breast-fedinfants may need additional iron (American Academy of Pediatrics Committee on Nutrition, 1976). In bottle-fed infants, the use of iron-fortified infant formula through the first year of life can prevent IDA (Ziegler & Foman, 1989). Unfortunately, a pervasive misconception exists among mothers and pediatric health-careproviders that iron-fortified formula causes gastrointestinal distress.A recent study by Nelson et al. (1988) reported no increasedregurgitation, flatus, fussiness, or stool frequency in infants fed iron-fortified formulas compared with infants fed low-iron formulas. In summary, regardlessof whether an infant is breastfed or bottle-fed, the need for increased iron and the ability to take solid foods occur simultaneously between 4 and 6 months of age. Once the infant is old enough for solid foods, iron-enriched dry infant cerealsare excellent first foods. n
CONCLUSION
The first year of life is perhapsthe single most important year of growth. Growth measurementsprovide the pediatric health-care provider with critical information about the infant’s past and current health. However, this information is available only if the infant is routinely and accurately measured. Unfortunately, becausethese are perceived as uncomplicated procedures, growth measurementsare often relegated to someone who is untrained and unaware of the importance of accuratemeasurements.Growth measurementsshould be taken under standard conditions on a routine basis, and the valuesobtained should be recorded and plotted immediately. G iven that each infant has an individual growth pattern, averageor standard values for height and weight should be considered only points of reference. More critical is that the infant exhibit a consistent pattern of growth across sequential measurements. REFERENCES Arner, K., August, G. P., & Robnett, M. A. (1992). The nursing penpective: Monitming and evaluation ofpwtb. Cahfon, NJ: Gardiner-Caldwell SvnerMed. American Academy of Pediatrics, Committee on Nutrition (1976). Iron supplementation for infants (BE1417). Pediatkx, 58, 765 768. Babson, S. G., Behrman, R. E., & Lessel, R. (1970). Fetal growth: Livebom birth weights for gestational age of white middle class infants. Pedhriu, 45, 937-944. Cowett, R. M., & S&L. (1985). The intrauterine growth retarded infant: Etiology, prenatal diagnosis, neonatal management, and long-term follow-up. In F. Lifshia (Ed.), Pediuti endmrimb~: A clinicalpide (pp. 109-128). New York: Marcel Dekker, Inc. Evans, D., Bowie, M. D., Hansen, J. D. L., Moodie, A. D., & van der Spuy, H. I. J. (1980). Intellectual development and nutrition. Journd of Pedhtriq 97 (3), 358-363.
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Fisher, S. E. (1985). The fetal alcohol syndrome. In F. Lifshitz (Ed.), Pediatric endocrinology: A clinicalguide (pp. 129-139). New York: Marcel Dekker, Inc. Fitzhardinge, P. M., & Steven, E. M. (1972). The small-for-date infant, 1: Later growth patterns. Pediatrics, 49, 671-681. Food and Agriculture Organization of the United Nations/World Health Organization joint ad hoc expert committee report, 22 March-2 April, 1971. (1980). Rome: National Academy of Sciences on Dietary AIlowances. handbook Forbes, G. B., &Woodruff, C. W. (1985). Pediahic nut&h (2nd ed). Elk Grove Village, Ill: American Academy of Pediatrics. Holt, K. S. (1991). Develupmentalpediuwics: Pempectivesandpruaice. London: Butterworth-Heinemann. IIlingwotth, R. S., & Lutz, W. (1965). Head circumference of infants related to body weight. Archives of Dtieases in Childhood, 40, 462469. Kelley, S. J., Walsh, J. H., &Thompson, K. (1991). Birth outcomes, health problems, and neglect with prenatal exposure to cocaine. Pediatric Nutsing 17 (2), 130-136. Korones, S. B. ( 1986). High-risk newborn infants: The basicfm intensive nursing care. St. Louis, MO: The CV Mosby Company. Krogman, W. M. (1972). Childgrowth. Ann Arbor, Mich: University of Michigan Press. Lowrey, G. H. (1986). Gruwtb and development of children (8th ed). Chicago: Year Book Medical Publishers, Inc. Lozoff, B. (1990). Has iron deficiency been shown to cause altered behavior in infants? In J. Dobbing (Ed.), Brain, behiur, and iron in the infant diet (pp. 107-125). New York: Springer-Verlag. Morton, N. E. (1955). The inheritance ofhuman birth weight.Annalr ofHuman Gemh, 20, 125-131. Nellhaus, G. (1968). Head circumference from birth to eighteen years. Pedhriq 41, 106-l 14. Nelson, S. E., Ziegler, E. E., Copeland, A. M., Edwards, B. B., & Foman, S. J. (1988). Lack of adverse reactions to iron-forci6ed formula. Pediatrics, 81, 360-364. Pinyerd, B. J., Zipf, W. B., Horswill, C. A., & Hayes, J. (1992). Variability in height determinations of children [Abstract]. Pedikc Research, 31 (4), 82A.
Volume 6, Number 5, Part 2 September-October 1992
Polani, P. E. (1974). Chromosomai and other genetic influences on birth weight variation. In Size at Birth. Amsterdam: CIBA Foundation Symposium, ASP. Smith, D. W. (1977). Gmvh and its disorden-mujor problem in clinicalpediatrics (Ed. 15). Philadelphia: W B Saunders Company. Smith, D. W., Truog, W., McCann, J. J., Rogers, J. E., Greitzer, L. G., Skinner, A. L., & Harvey, M. A. S. (1976). Shifting linear growth during infancy and the genetics of growth in infancy. Journal of Pediatrics, 89, 225230. Tanner, J. M. (1974). Variability of growth and maturity in newborn infants. In M. Lewis & L. Rosenblum (Eds.), Or&ins of behavim: The effect of the infint on its care&r. New York: John Wiley & Sons, Inc. Tanner, J. M. (1990). Standards of normal growth: Measuring techniques. In Fete into mwa (pp. 182-186). Cambridge, Mass: Harvard University Press. Tanner, J. M., Healy, M. J. R., Lockhart, R. D., Mackenzie, J. D., & Whitehouse, R. H. (1956). Aberdeen growth study, I: The prediction of adult body measurements from measurements taken each year from birth to 5 years. Archives of Diseases in Childhood, 31, 372-381. Waterlow, J. C., Buzina, R., Keller, W., Lane, J. M., Nicharnan, M. Z., &Tanner, J. M. (1977). The presentation and use of height and weight data for comparing the nutritional status of groups of children under the age of 10 years. Bulbtin of the World Health Organizatiun, 55 (4), 489-498. Zabriski, J. R. (1963). Effect of cigarette smoking during pregnancy: A study of 2000 cases. Obstetrical Gynewlqy, 21, 405-411. Ziegler, E. E. & Foman, S. J. (1989). Cow milk, gastrointestinal blood loss, and iron nutritional status of infants. In R. N. Hamburger (Ed.), Food intolerance in infamy: alfq~ob~, immunology, andgastmenterlogy (pp. 134-144). New York: Raven Press. Zuckerman, B., Frank, D., Hingston, R., Amaro, H., Levenson, S. M., Kayne, H. L., Cabral, H., Timperi, R., & Bauchner, H. (1989). Effects of maternal marijuana and cocaine use on fetal growth. Nav En&and Journal of Medicine, 320, 762-768.
Assessment of Infant Growth Belinda
J. Pinyerd,
n
PhD, MS, BSN
Growth is one of the best indicators of neonatal and infant well being. By comparing the growth of an individual infant over a period of time with available standards, the determination can be made, within limitations, whether the infant is doing as well as should be expected or whether any growth abnormalities exist. The three most common physical measurements of growth are weight, length/ height, and head circumference. Normal growth patterns and factors that impact growth within the first 2 years of life are discussed, with recommended techniques for assessment. J PEDIATR HEALTH CARE. (1992). 6, 302-308.
I
n pediatrics, the termsgrowth and development are often used interchangeably, but in a strict sense they are not synonymous. refers to proportionate changes in size; developmat refers to increasing complexity (Krogman, 1972). This article addresses fetal and infant growth through the first 2 years of life. Assessment of growth in infants is based primarily on weight measurements, given the accuracy and ease in making reliable determinations. As a single criterion of growth, however, measurement of length is a better criterion than is the measurement of weight. The third component of physical growth, specifically brain growth, is the head circumference. This article addresses these three components of physical growth in the fetus and the infant under 2 years of age, including normal and abnormal growth patterns, techniques for evaluation of growth, and factors affecting growth at the various stages of development.
G m vth
H NORMAL AND ABNORMAL GROWTH PATTERNS
Each developmental stage is characterized by patterns of growth that can be generally quantified, although wide intraindividual variability exists as a function of genetic, hormonal, nutritional, and environmental influences. Given that each child has an individual growth pattern, typical or average values for height and weight should be considered only points of reference. When sequential measurements are obtained, the percentile method of recording height and’weight is much more useful than tables stating means and standard deviations (Lowrey, 1986). This section categorizes the
Belinda j. Pinyerd, PhD, MS, BSN, is the Assistant Director of the Clinical Study Center and a nurse researcher in the Department of Nursing at Children’s Hospital in Columbus, Ohio. Reprint requests: Belinda 1. Pinyerd, PhD, MS, BSN, Clinical Study Center, Children’s Hospital, 700 Children’s Dr., Columbus, OH 43205. 25/o/40009
302
normal growth patterns across four developmental periods: intrauterine (conception to birth), neonatal (birth to 28 days), infant (1 to 12 months), and toddler (12 to 24 months). Intrauterine
(Conception
to Birth)
Intrauterine growth begins with conception and ends with birth. Although these are separate periods, fetal and neonatal growth are actually one continuous process, with birth and the beginning of extrauterine existence simply marking an important dividing point (Lowrey, 1986). The growth rate of the human fetus is determined by the number of cells that are present and their rate of division. Unfortunately, the precise mechanisms behind the regulation of cell division are unknown. Mer the period of major organogenesis, the fetus enters a period of incremental linear growth, achieving the greatest velocity at mid-fetal life (4 months). With the development of adipose tissue at about 7 months of gestation, an acceleration occurs in weight gain, with the weight doubling during the last 2 months in utero. At this stage, the fetus fills the uterine cavity to the extent that the uterine size becomes a constraining factor in late fetal growth. In terms of length, beginning with gestational week 25 the fetus grows 0.40 inches (1.0 cm) weekly. Peak lengthening, 0.54 inches (1.3 cm) weekly, occurs between 31 and 34 weeks. After that, growth velocity diminishes, and at 40 weeks the incremental rate is 0.20 inches (0.5 cm) per week (Korones, 1986). Some gender differences are apparent because the male fetus grows faster than the female fetus, predominantly after 32 weeks gestation. In both sexes, prenatal growth of the head is linear beginning with the latter half of pregnancy to about 32 weeks. At the maximal growth rates between 30 and 32 weeks, head circumference increases by 1.2 m m daily. Daily increments then diminish gradually, and at 40 weeks the rate of growth subsides to 0.2 m m daily. JOURNAL
OF PEDIATRIC
HEALTH
CARE
Journal of Pediatric Health
Neonate
Assessment
Care
(Birth
to 28 Days)
The average birth length in North America is about 20 inches (50 cm), and the mean birth weight is usually between 7.0 to 7.5 pounds (3.0 to 3.4 kg) (Lowrey, 1986). Birth length does not correlate well with midparental height (the mean height of the parents), the size of the father (Morton, 1955), or to the height of the same individual at maturity (Tanner, Healy, Lockhart, Mackenzie, & Whitehouse, 1956). Instead, birth length correlates best to the size of the mother only (Polani, 1974). Some gender differences have been noted in terms of physical growth. The newborn male averages 0.35 inches (0.9 cm) longer, is 150 gm heavier, and has a greater head circumference at full-term than the newborn female (Babson, Behrman, & Lessel, 1970). Male newborn babies also are slightly more muscular and less obese than female newborn babies (Tanner, 1974), possibly a consequence of elevated testosterone levels in the male fetus (Smith, 1977). Infant
(1 to 12 Months)
After birth, the infant shifts from a growth rate that is predominantly determined by maternal factors to one that is increasingly related to the infant’s genetic background and other physiologic factors. The first postnatal year is perhaps the most important single growth period of all (Krogman, 1972). Although individual growth rates are rapid and highly variable during the first year, the general rule of thumb is that birth weight trebles, birth length doubles, and birth head circumference increases by one third. Some infants exhibit delayed or accelerated growth rates as they compensate for or “adjust to” a constitutional percentile that is genetically driven. For example, small-for-gestational age neonates whose genetic background indicates larger size may grow somewhat more rapidly in the first 12 to 18 months than normal-weight neonates (Amer, August, & Robnett, 1992). Thus, newborns who are small for gestational age and who have the genetic capacity to “catch up” to the normal range generally will show accelerated growth within the first 6 months after birth. In contrast, most small-forgestational age babies who do not show catch-up growth during the first 6 months continue to grow at a slow rate into childhood and are generally destined to be of small stature (Fitzhardinge & Steven, 1972). Finally, those who are relatively large at birth but whose genetic background is for smaller size tend to maintain the prenatal growth rate for several months before beginning their deceleration into a lower growth channel (Smith et al., 1976). The postnatal pattern for linear growth returns to the pattern that existed in utero at 32 gestational weeks.
of Infant Growth
303
An infant’s height will increase approximately 1 inch per month in the first 6 months, and then gains will decrease to 0.5 inch per month in the second 6 months. By the end of the first year, the infant will increase in length approximately 50% and in weight by 150%. Toward the latter half of the first year, a gradual diminution in growth rate will occur, accompanied by a reduction in the degree of adiposity. During the first 6 months, the average baby gains close to 2.2 pounds (1 kg) per month, or nearly 1 ounce (30 gm) per day. Over the next 6 months the average increase is 1 pound per month. More than one half of healthy infants will have doubled their birth weight within 3 to 4 months, tripled it by 12 months, and quadrupled it by the end of the second year. Generally, weight gain is slightly greater in formula-fed infants as compared with breast-fed infants. Brain growth is particularly important given the fact that many aspects of human development are dependent on and occur as a result of brain development (Holt, 1991). The practitioner’s most useful guide to brain growth is measurement of the head circumference. At birth, the average head circumference is 13 to 14 inches (33 to 35 cm), which is about one half its adult size. Head circumference reaches 18 to 19 inches by 1 year of age. Postnatally, head circumference grows 1.1 m m daily (or 0.5 inches/month during the first 4 months), which is close to the intrauterine pace that existed before the slowing of growth at 32 weeks (Korones, 1986; Lowrey, 1986). Growth returns to the rate that existed in utero at 32 gestational weeks, increasing rapidly to about 75% of adult size by 18 months, and 90% by 4 years of age. Proportionally, the circumference of the head at birth is typically larger than the chest circumference, which is 12 to 13 inches (30 to 33 cm), but by 2 years of age the chest measurement is larger than that of the head. Head circumference is a measurement that has a relatively narrow range for any age group, with a standard deviation that remains small and nearly constant for the entire growing period. Almost no variation is due to racial, national, or geographic factors (Nellhaus, 1968). However, head circumference varies significantly as a function of body weight. Therefore, allowance should be made if the infant is much smaller or bigger than expected for the age (Illingworth & Lutz, 1965). Holt (1991) offers the following as a useful working rule: 1. Babies under 6 months of age: allow 0.50 inches (1.3 cm) in the head circumference for each 2.2 pounds (1 kg) deviation of body weight from the mean. 2. Babies aged 6 to 12 months: allow 0.40 inches (1.0 cm) in the head circumference for each 2.2 pounds (1 kg) deviation of body weight from the mean. Two other head measurements used for assessment
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5, Part 2 1992
predictions are ofien made basedon the following “rule of thumb” (Krogman, 1972):
BOYS: BIRTH TO 36 MONTHS PHYSICAL GROWTH NCHS PERCENTILES NAME
6, Number
September-October
RECORD#
Boys: 2 x height 5 x weight Girls: 2 x height 5 x weight
at age 2 years = adult height at age 2 = adult weight at 1% years = adult height at 1% years = adult weight
During the second year of life, growth rates begin to decline so that by the end of the third year, the child’s growth rate has settled into a steady, consistent pattern that will persist throughout childhood. Between 18 to 24 months the child grows at a fairly consistent rate of 2 to 3 inches (5 to 7.5 cm) yearly. During the second year, the averagemonthly weight increaseis about 0.5 pounds (0.25 kg), with the rate of gain steadily decreasing. After age 2 years, the approximate annual increase in weight will be 5 pounds (2.3 kg) until the child begins the adolescent growth spurt. The major period of brain growth is over, with the brain achieving 90% of its adult size by 4 years of age. As a consequence of this early, rapid brain growth, dramatic changescan be seen in the proportion of the head to the body. Unlike the brain, the rest of the body has a prolonged growth period. The limbs, for example, grow faster than the trunk from early fetal life until at least midadolescence. The trunk constitutes 75% of body mass in the infant and 67% in the child. Also of significance is that growth occurs earlier in the distal part of the leg than in the proximal segment. The foot of a 1X-year-old is one half of its adult size as compared with the femur, which does not achieve one half of its adult size until the child is 4 years of age. FIGURE 1 National
Center for Health Statistics chart for infant boys (a separate chart is available for tracking growth in infant girls). Reprinted by permission of Ross Laboratories, Columbus, OH 43216. n
purposes are the occipitofrontal and fontanelle diameters. Cranial bones and fontanelles fuse at predictable times during infancy, allowing for normal growth of brain tissue. The occipitofrontal range for full-term infants is 4.1 inches (10.5 cm) to 5.1 inches (13 cm). Molding, which occurs during labor, createsmuch variation that tends to invalidate the use of this method in the early neonatal period. At age 1 year, the mean diameter is 6.3 inches (16 cm), and at age 2 the mean diameter is 6.7 inches (17 cm). Unfortunately, fontanelle measurement is not practical given the wide variability in size and shape. Toddler (12 to 24 Months)
Childhood has been referred to as “the era of stable growth” (Smith, 1977). At age 24 months, adult size
n
EVALUATION
OF GROWTH
The keys to monitoring a child’s growth are accurate and consistent measurementsof length/height, weight, and head circumference. When a child is evaluated in a clinic setting the most common reason for an unexpected deviation in measurement is an error in technique. Hence, measurements should be repeated, recorded, and plotted immediately to reduce the chance of error. Growth rate and growth velocity measurements are plotted on standardized charts to allow for comparison of an individual child’s values with a statistical norm. Length is usually recorded from birth until the child is 2 to 3 years of age (Lowrey, 1986; Tanner, 1990) and should be plotted on a standard growth chart for infants 1 to 36 months of age (Figure 1). Two people are usually needed (one can be the parent) to measure an infant properly. The infant is measured nude in the supine position with the knee gently held flat and the head firmly held with the lower border of the orbit in the same vertical plane as the external auditory canal.
Journal of Pediatric Health Care
Assessment of Infant Growth
305
\ Gently Press Knees Down Moveable Baseboard
Gently Hdld Head in Position
n FIGURE 2 Infant length measurement on a measuring table.
The distance between a right-angle device held against the head and a right-angle device held against the base of the vertical foot is measured. Neonatometers and infantometers have been developedfor determining the length of neonates and infants, respectively, and are strongly recommended (Figure 2). Length should be assessedthree times in the first 6 months of life and then every 3 months until the child is age2 years.Height velocity calculations basedon lessthan 6-month assessment intervals should be interpreted with caution in view of the natural seasonalvariability and the expected technique error that have been reported (Pinyerd, Zipf, Horswill, & Hayes, 1992). Standing height is most commonly performed when the child is between 2 to 3 yearsof age. The first standing measurement also should include a separatemeasurement of length for comparison. Becauseof the body position, the standing height measurementtends to be slightly shorter than the supine length measurement. For recommended technique in the child 2 to 3 years of age, see the article by Henry in this supplement. Body weight should be measuredwith beam or balance scalesthat can be read to 0.2 pounds (0.1 kg) and go as high as 33 pounds (15 kg) and should be plotted on the growth chart (Figure 1). Calibrated or standard weights should be availableto check the accuracyof the scalesone to two times per year. Measurementsshould be made with the infant either unclothed or wearing a dry diaper. Whichever technique is preferred, it should be used consistently across all infants at all times. As with height determinations, weight measurement should be recorded and plotted immediatelyon all routine and acute care visits. When a problem is suspected, weight should be assessedevery 2 to 3 weeks with the same technique and the same examiner if possible. Head circumference is measuredwith a nonstretchable tape firmly placedfrom the maximal occipital prominence around to the areajust above the eyebrow (Fig-
n
FIGURE 3 Head circumference
measurement.
ure 3). Measuring the head circumferenceis often easier if the measurementis taken from behind the infant, with the infant seated on an adult’s lap. The head circumference measurement should be repeated after completely removing the tape from the head to ensure accuracy. Keep in mind that thick hair, braids, or big ears can get in the way when measuring head circumference, leading to falsely high measurements.For example, 1 mm of scalp-hair thickness increasesthe total circumference by approximately 6 mm. Fortunately, the most critical period for following head growth is during the first 2 years, when scalp-hair thickness is less of a confounding problem. n
FACTORS AFFECTING GROWTH
PATTERNS
Normal growth from infancy through adolescencedepends on adequatenutrition (in both quantity and quality of caloriesingested), normal endocrine function, absence of chronic disease, normal genetic make-up, and a normal emotional environment. A variety of fetal, infant, environmental, and maternal factors can interact to retard intrauterine and postnatal growth (Box). Growth failure can be classified as being either primary or secondary. In primary prenatal-onsetgrowth deficiency, the skeletal cells’capacity for growth is affected, resulting in growth deficiency. Most of these disorders are either chromosomal abnormalities or mutant gene disorders within the fetus (Smith, 1977). O ther primary factors that may affect fetal growth include maternal intrauterine infection or normal-heredity small stature. To date, no effective mode of therapy existsto increasethe stature of children with primary cellular growth deficiency (Smith, 1977).
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Volume 6, Number September-October
Pinyerd
n &OX
CAUSES AND lNFANT
OF FETAL, NKINATAL, GROWTtl FAWJRE
Envirotpmental Ethnic Race Socioeconomic status Geographic location Deprivation syndrome
Congenital anomalies Chromosomal defects Multiple gestation
Infant
Maternal
Nutritional Inadequate intake Malabsorption Partial obstruction Mental deficiency Cardiac defect Respiratory insufficiency Renal dysfunction Hypothyroidism Metabolic disorders Pituitary growth hormone deficiency Chronic serious infection
Small stature Primiparity Grand multiparity Low prepregnancy weight Young maternal age Smoking Ethanol intake Heroin addiction Hypertension Renal disease Heart disease Syphilis Cytomegalovirus Rubella Toxemia
Secondary growth deficiency occurs as a result of an extrinsic causeoutside the skeletal system, most typically the mother. One type of secondary deficiency entails diminution of maternal support prenatally to a fetus that otherwise would have been normal (Korones, 1986). This deficiency is generally mild in infants born of mothers with malnutrition, toxemia, hypertensive kidney disease,heart disease,moderate ethanol intake, or heavy cigarette smoke ingestion. Weight is affected more than length, without obvious malproportion or anomalies. Most infants show catch-up growth, but overall postnatal growth is variable. Infants with more severeprenatal growth deficiency, however, may not show appreciable catch-up growth. Intrauterine growth retardation (IUGR) is a clinical term defining in utero growth failure as a result of prenatal insult (Cowett & Stern, 1985). These infants, differentiated by having failed to achieve normal expected growth, are clustered on the growth charts at the lower end of the spectrum for weight and length at their gestational age. Secondarypostnatal-onset growth failure occurs after birth but, again, originates in a problem outside of the skeletal system, either in the delivery of nutrients, hormones, or oxygen to the cells. Examples of problems that may result in growth failure include inadequate
5, Part 2 1992
nutrient intake, intestinal obstruction, malabsorption, emotional and/or physical deprivation, mental deficiency, heart defect, respiratory insufliciency, renal dysfunction, hypothyroidism, and metabolic disorders such as glycogen storage disease. Once specific therapy is aimed at correcting the causeof growth failure, dramatic catch-up growth can occur, depending on the age of onset, the duration, and the nature of the original growth problem (Smith, 1977). Of all the factors that affect growth, several warrant further discussion, given their dramatic affects. Smoking
The woman who smokes produces a small-sized infant. Fortunately, smoking cessation before the third trimester can ameliorate the effect of smoking on fetal weight (Zabriski, 1963). Th eref ore, the health-carepractitioner should expend extra effort with newly pregnant women who smoke to get them to break the habit before the sixth month of pregnancy. Alcohol
Infants born with fetal alcohol syndrome exhibit an altered pattern of growth and morphogenesis that include prenatal and postnatal growth deficiencies in height and weight. Few of these infants exhibit the usual neonatal catch-up growth observed in small-for-gestational age newborns. Infants with fetal alcohol syndrome remain growth-deficient throughout childhood; most remain more than two standard deviations below the mean for age in both height and weight (Fisher, 1985). Drugs
Exposure of the fetus to illicit drugs such as marijuana, cocaine, and heroin is often associatedwith IUGR and prematurity. Recent studies have shown that maternal cocaine use is related to decreasedbirth weight, head circumference, and birth length (Kelley, Walsh, & Thompson, 1991; Zuckerman et al., 1989). Furthermore, cocaine-exposedinfants may be at increased risk for inadequate gains in weight and height during the first 2 years of life (Kelley, Walsh, & Thompson, 1991). Maternal
Nutrition
During pregnancy, the expectant mother’s requirements for all nutrients increase. Obviously, a balanced diet basedon a variety of foods is the best way to ensure an adequateintake of all the nutrients. Unless the mother’s nutrition is very poor, the fetus is able to obtain adequate nutrition for prenatal growth, even at the expense of depleting the mother (Smith, 1977). Severe malnutrition during the period of most rapid brain growth is associatedwith permanent reduction in the total num-
Journal of Pediatric Health Care
ber of fetal brain cells. In humans, this critical period probably begins at about 15 gestational weeks and ends between 8 to 15 months after term. Continuous severe malnutrition during this period can result in permanent effects on brain size, composition, number of cells, and the production of glia and myelination, which may be critical for intellectual functioning (Evans, Bowie, Hansen, Moodie, & van der Spuy, 1980). Infant Nutrition
Growth is the single most valuable indicator of nutritional status and generalhealth in childhood (Waterlow et al., 1977) becausethe rate of change in stature (that is, growth velocity) is sensitive to nutritional deprivation. Not surprisingly given the strides in growth that occur during the first year of life, the nutritional needs are the greatest at this time. The energy requirements for a healthy infant during the first 6 months average 115 kcal/kg/day and gradually decrease to 105 kcallkglday by the end of the first year. During the secondyear, 100 kcal/kg/day provide sufficient energy for growth (Food and Agriculture Organization of the United Nations/World Health Organization, 1980). Breast milk and most formulas provide the major source of calories during the first 6 months, each having approximately 20 kcal/ounce. The appropriate distribution of calories into proteins, lipids, and carbohydrates is essential.Most of the dietary requirementscan be met by breast milk or formula during the first 6 months of life. During the second 6 months of life, the infant’s diet consists of breast milk or formula, mixed feedings, and increasedamounts of table foods. Cereal should be fortified with iron. O ther vitamin and mineral supplements usually are not required, although the diet must include an adequate source of vitamin C. During the toddler years,little basis exists for routine vitamin and mineral supplementation in normal children (Forbes & Woodruff, 1985). One mineral that warrants mention is iron. Iron deficiency anemia (IDA) remains the most common nutritional deficiency in North America. The infant between 6 and 12 months of age is particularly vulnerable in terms of long-term deficits in mental and motor development (Lozoff, 1990). IDA could develop in infar& fed cow milk before 12 months of age. bespite being advised against it, many parents introduce cow milk early becauseof its convenience and lower cost compared with infant formulas. Cow milk is a poor source of iron and, when introduced before the infant is 1 year of age, can causeintestinal blood loss. Fortunately, IDA is easily prevented. Breast milk alone gives most infants all the iron needed during the first 4 months of life. When the infant is premature or
Assessment
of Infant Growth
307
anemic, however, iron stores are depleted earlier, so earlier supplementation is warranted. After 4 months, breast-fedinfants may need additional iron (American Academy of Pediatrics Committee on Nutrition, 1976). In bottle-fed infants, the use of iron-fortified infant formula through the first year of life can prevent IDA (Ziegler & Foman, 1989). Unfortunately, a pervasive misconception exists among mothers and pediatric health-careproviders that iron-fortified formula causes gastrointestinal distress.A recent study by Nelson et al. (1988) reported no increasedregurgitation, flatus, fussiness, or stool frequency in infants fed iron-fortified formulas compared with infants fed low-iron formulas. In summary, regardlessof whether an infant is breastfed or bottle-fed, the need for increased iron and the ability to take solid foods occur simultaneously between 4 and 6 months of age. Once the infant is old enough for solid foods, iron-enriched dry infant cerealsare excellent first foods. n
CONCLUSION
The first year of life is perhapsthe single most important year of growth. Growth measurementsprovide the pediatric health-care provider with critical information about the infant’s past and current health. However, this information is available only if the infant is routinely and accurately measured. Unfortunately, becausethese are perceived as uncomplicated procedures, growth measurementsare often relegated to someone who is untrained and unaware of the importance of accuratemeasurements.Growth measurementsshould be taken under standard conditions on a routine basis, and the valuesobtained should be recorded and plotted immediately. G iven that each infant has an individual growth pattern, averageor standard values for height and weight should be considered only points of reference. More critical is that the infant exhibit a consistent pattern of growth across sequential measurements. REFERENCES Arner, K., August, G. P., & Robnett, M. A. (1992). The nursing penpective: Monitming and evaluation ofpwtb. Cahfon, NJ: Gardiner-Caldwell SvnerMed. American Academy of Pediatrics, Committee on Nutrition (1976). Iron supplementation for infants (BE1417). Pediatkx, 58, 765 768. Babson, S. G., Behrman, R. E., & Lessel, R. (1970). Fetal growth: Livebom birth weights for gestational age of white middle class infants. Pedhriu, 45, 937-944. Cowett, R. M., & S&L. (1985). The intrauterine growth retarded infant: Etiology, prenatal diagnosis, neonatal management, and long-term follow-up. In F. Lifshia (Ed.), Pediuti endmrimb~: A clinicalpide (pp. 109-128). New York: Marcel Dekker, Inc. Evans, D., Bowie, M. D., Hansen, J. D. L., Moodie, A. D., & van der Spuy, H. I. J. (1980). Intellectual development and nutrition. Journd of Pedhtriq 97 (3), 358-363.
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Fisher, S. E. (1985). The fetal alcohol syndrome. In F. Lifshitz (Ed.), Pediatric endocrinology: A clinicalguide (pp. 129-139). New York: Marcel Dekker, Inc. Fitzhardinge, P. M., & Steven, E. M. (1972). The small-for-date infant, 1: Later growth patterns. Pediatrics, 49, 671-681. Food and Agriculture Organization of the United Nations/World Health Organization joint ad hoc expert committee report, 22 March-2 April, 1971. (1980). Rome: National Academy of Sciences on Dietary AIlowances. handbook Forbes, G. B., &Woodruff, C. W. (1985). Pediahic nut&h (2nd ed). Elk Grove Village, Ill: American Academy of Pediatrics. Holt, K. S. (1991). Develupmentalpediuwics: Pempectivesandpruaice. London: Butterworth-Heinemann. IIlingwotth, R. S., & Lutz, W. (1965). Head circumference of infants related to body weight. Archives of Dtieases in Childhood, 40, 462469. Kelley, S. J., Walsh, J. H., &Thompson, K. (1991). Birth outcomes, health problems, and neglect with prenatal exposure to cocaine. Pediatric Nutsing 17 (2), 130-136. Korones, S. B. ( 1986). High-risk newborn infants: The basicfm intensive nursing care. St. Louis, MO: The CV Mosby Company. Krogman, W. M. (1972). Childgrowth. Ann Arbor, Mich: University of Michigan Press. Lowrey, G. H. (1986). Gruwtb and development of children (8th ed). Chicago: Year Book Medical Publishers, Inc. Lozoff, B. (1990). Has iron deficiency been shown to cause altered behavior in infants? In J. Dobbing (Ed.), Brain, behiur, and iron in the infant diet (pp. 107-125). New York: Springer-Verlag. Morton, N. E. (1955). The inheritance ofhuman birth weight.Annalr ofHuman Gemh, 20, 125-131. Nellhaus, G. (1968). Head circumference from birth to eighteen years. Pedhriq 41, 106-l 14. Nelson, S. E., Ziegler, E. E., Copeland, A. M., Edwards, B. B., & Foman, S. J. (1988). Lack of adverse reactions to iron-forci6ed formula. Pediatrics, 81, 360-364. Pinyerd, B. J., Zipf, W. B., Horswill, C. A., & Hayes, J. (1992). Variability in height determinations of children [Abstract]. Pedikc Research, 31 (4), 82A.
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Polani, P. E. (1974). Chromosomai and other genetic influences on birth weight variation. In Size at Birth. Amsterdam: CIBA Foundation Symposium, ASP. Smith, D. W. (1977). Gmvh and its disorden-mujor problem in clinicalpediatrics (Ed. 15). Philadelphia: W B Saunders Company. Smith, D. W., Truog, W., McCann, J. J., Rogers, J. E., Greitzer, L. G., Skinner, A. L., & Harvey, M. A. S. (1976). Shifting linear growth during infancy and the genetics of growth in infancy. Journal of Pediatrics, 89, 225230. Tanner, J. M. (1974). Variability of growth and maturity in newborn infants. In M. Lewis & L. Rosenblum (Eds.), Or&ins of behavim: The effect of the infint on its care&r. New York: John Wiley & Sons, Inc. Tanner, J. M. (1990). Standards of normal growth: Measuring techniques. In Fete into mwa (pp. 182-186). Cambridge, Mass: Harvard University Press. Tanner, J. M., Healy, M. J. R., Lockhart, R. D., Mackenzie, J. D., & Whitehouse, R. H. (1956). Aberdeen growth study, I: The prediction of adult body measurements from measurements taken each year from birth to 5 years. Archives of Diseases in Childhood, 31, 372-381. Waterlow, J. C., Buzina, R., Keller, W., Lane, J. M., Nicharnan, M. Z., &Tanner, J. M. (1977). The presentation and use of height and weight data for comparing the nutritional status of groups of children under the age of 10 years. Bulbtin of the World Health Organizatiun, 55 (4), 489-498. Zabriski, J. R. (1963). Effect of cigarette smoking during pregnancy: A study of 2000 cases. Obstetrical Gynewlqy, 21, 405-411. Ziegler, E. E. & Foman, S. J. (1989). Cow milk, gastrointestinal blood loss, and iron nutritional status of infants. In R. N. Hamburger (Ed.), Food intolerance in infamy: alfq~ob~, immunology, andgastmenterlogy (pp. 134-144). New York: Raven Press. Zuckerman, B., Frank, D., Hingston, R., Amaro, H., Levenson, S. M., Kayne, H. L., Cabral, H., Timperi, R., & Bauchner, H. (1989). Effects of maternal marijuana and cocaine use on fetal growth. Nav En&and Journal of Medicine, 320, 762-768.