Version July 2025
INTRODUCTION —
Early infancy is normally a period of rapid growth. Growth impairment during this time can have adverse effects on neurodevelopment, and abnormalities may persist into adulthood, especially in individuals who were born preterm.
Preterm infants are at risk for poor growth while in the neonatal intensive care unit (NICU) and after discharge from the NICU due to difficulties in transitioning from tube to oral feeding and increased nutritional needs compared with their term counterparts, often compounded by suboptimal feeding practices and inadequate parental support and guidance regarding feeding practices at home. They must be closely monitored and may require interventions to promote better growth.
This topic will provide an overview of growth and feeding for the preterm infant after NICU discharge. Other UpToDate topics with related guidance are:
●(See "Approach to enteral nutrition in the premature infant".) – Discusses feeding in the NICU, including caloric goals, advancement, and transitions to oral feeds.
●(See "Breastfeeding the preterm infant".) – Discusses challenges and techniques for transitioning a preterm infant to direct breastfeeding.
●(See "Human milk feeding and fortification of human milk for premature infants".) – Discusses the nutritional content of human milk and fortifiers.
TARGET GROWTH RATES FOR PRETERM INFANTS
Target postdischarge growth rates — The goal of adequate nutrition is to support optimal growth and neurodevelopment in infants. To monitor nutritional adequacy effectively, we recommend tracking weight, length, and head circumference measurements over time. These longitudinal assessments are essential components of routine growth monitoring in preterm infants [1].
●Weight – For preterm infants discharged with a weight below 2 kg, the goal is a weight gain of approximately 15 to 20 g/kg/day over a minimum of five to seven days. Once the preterm infant reaches 2 kg body weight, the goal can be a weight gain of 20 to 30 g/day until approximately 52 weeks postmenstrual age (PMA). Note that these targets refer to g/kg/day for the smaller infants (to focus on relative weight gain, given the wide range in actual body weight), then switch to g/day once the infant reaches 2000 g (because absolute weight gain is relatively constant after this point).
Although these are commonly used targets for weight gain, using weight Z-scores or centiles is also valuable for monitoring purposes. (See 'Routine growth monitoring' below.)
●Length – Length is expected to increase at a rate of approximately 1 cm/week, but fluctuations between periods of growth spurts and periods of no growth should be anticipated up to two to three months of corrected age [1]. To ensure an accurate reference point, the length at discharge should ideally be measured with a length board because measuring with tapes and length boards can differ by an average of 2 cm [2].
●Head circumference – Head circumference should increase by approximately 1 cm/week up to three months of corrected age.
Growth charts — For preterm infants, the selection of growth chart used depends on local practice and preference. We suggest the following approach:
●Fenton chart – For infants 36 to approximately 50 weeks corrected age (ie, up to 10 weeks post-term), we suggest using the Fenton chart (figure 1A-B) to assess longitudinal growth [3].
●World Health Organization (WHO) charts – After 50 weeks corrected age (ie, after 10 weeks post-term), we suggest using the WHO growth charts that are also used for infants born at term (females, males). However, for preterm infants, the corrected age should be used when plotting growth until 24 months of age. (See "Measurement of growth in children", section on 'Infants 0 to 2 years'.)
All systems for monitoring growth in preterm infants have inherent limitations. For infants greater than 44 weeks corrected PMA, the preterm infant is being compared with the term infant who has already undergone normal postnatal weight loss. For the infants below 36 weeks corrected age, the growing preterm infant (who has already undergone normal postnatal weight loss) is often compared with the newborn preterm who has not undergone normal postnatal weight loss.
To overcome this, in the Fenton charts, the birth weight cohorts were "smoothed" into reference charts of term-born infants. Although this method has been criticized, the Fenton charts have been validated as a growth monitoring tool in preterm infants [4]. However, this smoothing approach means that they are not fully accurate in classifying newborn near-term and term infants as being appropriate for gestational age, small for gestational age, or large for gestational age. As a result, after eight weeks post-term, the WHO growth charts should be used.
●Other charts – Two additional reference charts have been published. However, both are limited by the narrow range of gestational ages that are covered, which limits their usefulness in tracking growth:
•INTERGROWTH 21st charts – These charts are designed for preterm infants with PMA between 24 and 33 weeks, based on data collected from centers from eight different global locations (Brazil, Italy, China, India, the United Kingdom, Kenya, Oman, and the United States) and with diverse ethnic backgrounds [5,6]. This growth reference was based on a relatively small dataset. In addition, there remain concerns that an international growth reference is unrealistic due to the differences in growth between populations with different genetic and environmental backgrounds [7]. Finally, there is some limited evidence that the INTERGROWTH-21st charts are less accurate predictors of developmental outcomes than the fetal growth references (eg, Fenton or Olsen curves) [8,9].
•Vermont Oxford Network – Weight and head circumference charts for preterm infants with PMA between 22 and 29 weeks were developed using data from the Vermont Oxford Network [10]. These charts are representative of a racially diverse dataset with similar measurements to the Fenton charts.
MANAGEMENT OF GROWTH AND NUTRITION AFTER NICU DISCHARGE —
Overall goals for nutritional management are to:
●Promote human milk feeding – Human milk, ideally from the infant's mother, remains the preferred source of nutrition for preterm infants after NICU discharge due to possible benefits on long-term immunologic, metabolic, and developmental outcomes [11].
●Achieve growth trajectories – Achieving weight and length goals is critical to support healthy development and reduce long-term complications associated with prematurity. The goal is to achieve the body composition and rate of growth of a normal fetus/infant of the same postmenstrual age (PMA) during the first entire year of life [12]. Some infants, even those without major comorbidities, are not able to achieve this goal during the first year, but many can still catch up to their growth potential by age three years [13]. Ongoing efforts to optimize growth are important, although they can put considerable strain on the families and clinicians [1].
●Minimize nutrient deficits – Preterm infants are at relatively increased risk for multiple nutrient deficiencies, particularly in calcium, phosphorus, zinc, iron, and protein. Ensuring adequate intake of these nutrients is essential for skeletal growth and overall health.
The steps to achieve these goals are outlined in the following sections, followed by troubleshooting for common problems.
Routine growth monitoring — Ongoing monitoring of growth is the essential first step in the management of growth in these infants.
●Frequency of visits – Growth parameters (weight, length, and head circumference) should be monitored every one to two weeks for the first four to six weeks after hospital discharge. After this initial period of close observation, infants who are growing normally can be monitored every month and then every two months.
After 40 weeks PMA, continue follow-up visits every two to four weeks for infants with slow weight gain, those who remain below the third percentile, those with weight or height Z-score <-2 (ie, more than 2 standard deviations below the mean) [1], or those with chronic health problems (eg, bronchopulmonary dysplasia [BPD]). Close monitoring should continue until a steady adequate growth pattern is established [14].
●Charting – Growth outcomes in preterm infants are typically assessed using centiles and Z-scores based on the 2013 Fenton growth curves, until the infant is approximately 50 weeks PMA (figure 1A and figure 1B), at which point, the World Health Organization (WHO) growth curves for term infants can be utilized [15,16]. Corrections for gestational age should be made for weight through 24 months of age, for stature through 40 months of age, and for head circumference through 18 months of age. (See 'Growth charts' above.)
•Weight – Weight gain is the primary measure to track progress because it reflects short-term changes in nutrition. Weight changes should be evaluated by assessing growth curves using weight Z-scores (preferred) or percentiles, with discharge values as a reference point. After discharge, monitoring weight gain in g/day is often a practical approach. A weight gain of 20 to 30 g/day over a minimum period of five to seven days often correlates with favorable changes in weight Z-scores.
Interpretation of weight Z-scores:
-A weight Z-score drop of 0.8 units during the first two weeks of life reflects physiologic weight loss [17], while a more significant drop of 1.2 units from birth to 36 weeks PMA is indicative of moderate to severe malnutrition [18].
-After NICU discharge, further declines in weight Z-scores are not expected, particularly for those preterm infants who already have drops in Z-scores from birth to 36 weeks PMA that indicate moderate to severe malnutrition. A reasonable goal is to maintain a weight Z-score similar to the weight Z-score at the time of NICU discharge until the infant reaches term-equivalent age.
-At 36 weeks gestational age, nearly one-quarter of preterm infants have weight and length Z-scores <-2, including those born small for gestational age. However, many infants continue to catch up in growth metrics during subsequent follow-up, demonstrating that ongoing monitoring and individualized care are critical for supporting healthy growth trajectories. Most preterm infants without complications experience gradual catchup growth so that their weight, length, and head circumference are all within the normal range (Z-scores >-2) by 36 months corrected age [13].
For preterm infants who experience significant complications during their NICU stay, such as BPD, somewhat lower growth may need to be tolerated, for example, due to bowel injury or exposure to glucocorticoids. Growth assessments in these infants should be guided by multidisciplinary teams managing their postdischarge care.
•Length and head circumference – Linear and head growth should be monitored consistently but can be followed less frequently than weight.
These parameters can be affected by long-term nutritional status or other factors, and significant deficits are correlated with cognitive outcomes. As an example, in one report, length Z-score <-1 at 36 weeks PMA or a head circumference Z-score decline of 2 or greater between birth and 36 weeks PMA was associated with the risk of cognitive impairment at two years of age [9]. In another report, preterm infants whose head circumference was below the normal range (Z-score <-2) at eight months corrected age had worse cognitive function, academic achievement, and behavior at eight years of age compared with those whose head circumference was in the normal range [19]. Infants with these characteristics warrant special attention after NICU discharge to avoid further declines in length and head circumference Z-scores.
In addition, infants and young children who have a very low height Z-score may need further evaluation for growth retardation, including consultation by a pediatric endocrinologist. By three years of age, fewer than 6 percent of former preterm infants will have length Z-scores <-2 [1]. Referral is based on the extent of the shortness, parental concern, and whether catchup growth has occurred. (See "Diagnostic approach to children and adolescents with short stature".)
Slow head growth is associated with developmental delay. Infants with abnormal head growth should have neuroimaging studies to evaluate the cause. A rapid increase in head circumference may indicate posthemorrhagic hydrocephalus. (See "Germinal matrix and intraventricular hemorrhage (GMH-IVH) in the newborn: Management and outcome".)
Vitamin and mineral supplements — Additional nutritional needs for human milk-fed infants are:
●Iron – Iron should be provided at an intake of 2 to 4 mg/kg/day, beginning at two weeks of age. In infants fed unfortified human milk, this is given as a separate iron supplement. Even if the infant is discharged on an enriched diet (ie, human milk plus supplements of human milk fortifier or preterm formula), the diet is unlikely to supply sufficient iron to meet the recommended needs. For formula-fed infants, the formula usually supplies all or most of the iron requirement (2 to 4 mg/kg/day). (See "Iron deficiency in infants and children <12 years: Screening, prevention, clinical manifestations, and diagnosis", section on 'Recommendations for iron supplementation' and "Human milk feeding and fortification of human milk for premature infants", section on 'Indications and fortifier types'.)
●Vitamin D – Supplemental vitamin D (at least 400 international units [10 micrograms] daily) should be given to all human milk-fed infants, beginning during the first month of life and continued until the target intake is supplied by other components of the diet. This can be supplied by a human milk fortifier (which also provides supplemental calcium and phosphorus) or as a separate vitamin D supplement. Some premature infants might remain at increased risk for rickets after NICU discharge and warrant vigilance for adequate intake of vitamin D, calcium, and phosphorus and any clinical evidence of rickets. (See "Overview of rickets in children" and "Management of bone health in preterm infants".)
Laboratory monitoring — Laboratory monitoring (eg, serum calcium, phosphorus, and alkaline phosphatase) is generally unnecessary in the evaluation of the poorly growing NICU graduate. An exception is an elevation of serum alkaline phosphatase for selected infants, which is a marker for osteopenia and rickets and is associated with reduced stature later in life [20]. Monitoring of serum alkaline phosphatase may be appropriate for very low birth weight infants with one or more of these characteristics:
●Persistently elevated alkaline phosphatase (>800 international units), elevated parathyroid hormone, or radiographic signs of rickets before hospital discharge [21].
●Severe metabolic bone disease [21,22].
(See "Management of bone health in preterm infants", section on 'Infants with rickets'.)
General approach to feeding — Postdischarge nutrition plans should be individualized, taking into account PMA at discharge, the mother's goals (breastfeeding, expressed milk, or formula feeding), the infant's growth status, and the potential need for milk fortification [11]. Traditional discharge feeding plans often fail to meet the protein and calcium/phosphorus needs of preterm infants, even when using fortified breast milk or a standard postdischarge formula.
●Discharge planning – Prior to NICU discharge, infants should have a nutritional evaluation and a feeding plan should be developed. This should account for factors that interfered with growth in the NICU and provide a baseline for serial monitoring of weight, length, and head circumference after discharge. Additionally, an assessment should be made of the home environment, including eligibility for government nutrition or medical assistance programs, because lack of social support may be associated with growth faltering (eg, poor weight gain).
At the time of NICU discharge, most infants are feeding orally and gaining weight on ad libitum quantities of human milk or formula. Less commonly, fluid intake may be limited at prescribed levels or tube feeding (or other artificial means of feeding) is used. Whatever the feeding plan is, appropriate growth should be demonstrated on the proposed discharge feeding regimen while the infant is hospitalized. (See "Approach to enteral nutrition in the premature infant", section on 'Discharge planning'.)
●Risk assessment – The postdischarge feeding plan should be guided by careful consideration of the infant's risk factors for nutritional deficiency. Factors that often interfere with growth in the NICU include comorbidities associated with prematurity (patent ductus arteriosus, BPD, intraventricular hemorrhage, or necrotizing enterocolitis) and delays in establishing full enteral feeding with fortified milk. The effect of these risk factors on growth will be reflected in significant declines in weight Z-scores or percentiles from birth to 36 weeks PMA or NICU discharge. These declines could be more pronounced in stable infants because they have shorter NICU stays.
●Goals for energy intake – In practice, monitoring actual energy intake after NICU discharge can be difficult. For infants who are directly breastfeeding, the volume can be measured by weighing the infant before and after the feed, but this adds a burden for the caregiver and should generally be implemented selectively. Furthermore, if donor milk is used after discharge, estimation of caloric intakes is more difficult and higher intakes or increased levels of fortification may be needed.
●Cue-based versus scheduled feeding – Although scheduled feeding is a common practice prior to hospital discharge, there may be some benefits to converting to cue-based (ad libitum) feeds after hospital discharge [23]. It is not clear whether this method of feeding will improve overall growth or reduce the number of infants with feeding problems, including those who require orogastric or nasogastric feeds after discharge. Nevertheless, further investigation of this feeding method is warranted to see if there is any additional benefit of cue-based feeding over the traditional feeding based on a fixed time schedule. (See "Initiation of breastfeeding", section on 'Feed with every cue'.)
Enriched diet
Indications
●While in NICU – During the NICU hospitalization, most institutions provide an enriched diet for infants with birth weight <2000 or 2500 g, although the evidence for this threshold is limited and practice varies. These infants are at increased risk for slow weight gain and osteopenia, and the enriched diet addresses both of these issues. For infants with higher birth weights, an enriched diet is provided on a case-by-case basis, depending on the infant's growth trajectory and diet, feeding problems, and any underlying medical issues. Indications and implementation of an enriched diet during the NICU hospitalization are discussed separately. (See "Approach to enteral nutrition in the premature infant", section on 'Enriched diet'.)
●After NICU discharge – Decisions about enriched feeds after NICU discharge are individualized and depend on the infant's growth trajectory and the goals, preferences, and resources available to the family. We generally use an enriched diet, as follows:
•For infants who have required an enriched diet to achieve adequate growth rates while in the NICU, enriched feeds should generally be continued after hospital discharge. This typically includes those with birth weight <1500 g or declines in weight-for-age Z-scores greater than 1.2 between birth and 36 weeks PMA.
•For formula-fed infants, we generally prescribe an enriched diet (ie, a "postdischarge formula") for infants <2000 g birth weight, rather than switching to a term formula at NICU discharge. Other centers may choose to use a term formula for infants >1500 g birth weight who are growing well.
•The threshold for prescribing an enriched diet may be less stringent for breastfed infants (to allow for direct breastfeeding) (see 'Strategies' below) or for formula-fed infants with limited access to an appropriate postdischarge formula due to cost or other considerations.
•For infants who are initially discharged on unenriched feeds, the diet may be advanced to an enriched diet if they show signs of growth faltering after NICU discharge.
•Infants should get at least 48 to 72 hours of the proposed home feeding regimen prior to NICU discharge to allow for initial assessment of feeding tolerance and growth.
Limited evidence suggests a small benefit on growth outcomes for feeding an enriched diet after hospital discharge [12,24-27]. Most of the evidence is for infants <1750 g birth weight who are formula fed. As an example, a meta-analysis found no benefit of feeding postdischarge formula compared with standard term formula [26]. However, most of the trials were on a heterogenous population of preterm infants, rather than those at increased risk (eg, very low birth weight), and focused on growth rather than bone health or other outcomes. Moreover, whether these benefits are sustained and how they affect long-term health are unclear. Additional support for enriched feeds comes from trials evaluating the benefit of enriched feeds during the NICU hospitalization. (See "Approach to enteral nutrition in the premature infant", section on 'Enriched diet'.)
Strategies — The composition and duration of the enriched diet can be adjusted as needed depending on the infant's growth rate. Once initiated, the enriched diet generally should be maintained until it has achieved its goals (normalization of growth rate and achievement of catchup growth as appropriate). Typically, we would continue beyond term-corrected age, eg, to 48 or 52 weeks PMA. The specific strategies are individualized depending on the infant's needs, caregivers' preferences, and available resources:
●Human milk-fed infants – During the NICU stay, we fortify the milk by adding human milk fortifier (see "Human milk feeding and fortification of human milk for premature infants", section on 'Fortification of human milk'). Whether and how to continue the fortification after hospital discharge depends on several factors, including the infant's growth trajectory and whether they are directly breastfeeding, because an enriched diet requires at least some bottle feeding.
Unfortunately, the need for fortification competes with direct breastfeeding. Exclusive breastfeeding rates tend to drop by nearly 50 percent within the first 28 days after NICU discharge [28], highlighting the need for tailored feeding plans that support the combined goals of breastfeeding, optimal growth, and bone health. If "supplementary" formula feeds are recommended, they will likely displace a proportion of human milk from the diet.
Thus, the approach to fortification should be individualized to balance all of these goals in the context of the family's preferences and available resources. Examples of approximate nutrient intake from different approaches to fortified feeds are shown in the table (table 1). Options include:
•Directly breastfeed five or six times/day, plus two or more bottle feeds of fortified breast milk or formula at 30 kcal/ounce (1 kcal/mL). These are sometimes called "rescue feeds."
•Directly breastfeed three or four times/day, alternating with four or five bottle feeds of fortified breast milk or formula at 27 kcal/ounce (0.9 kcal/mL) or more [29].
•One alternative that has been described is to directly breastfeed ad libitum (eg, eight times a day), plus four to six "shots" of human milk fortifier (where "shot" refers to a commercially available human milk fortifier mixed with small volumes of expressed breast milk, given just prior to breastfeeding) [30,31].
•For infants feeding expressed breast milk, each feed can be fortified to 24 kcal/ounce (0.8 kcal/mL) or more with a liquid human milk fortifier [32]. Powder preterm formula is sometimes used, but some clinicians avoid this approach for infants <44 weeks gestational age because of the risk of contamination [29].
●Formula-fed infants – Commercially available postdischarge formulas are calorically denser compared with standard term formulas (usually 22 kcal/ounce [0.75 kcal/mL] versus 20 kcal/ounce [0.67 kcal/mL]). Postdischarge formulas also have a higher content of protein, calcium, phosphorus, zinc, and some vitamins. For infants who initially received a postdischarge formula who do not maintain adequate growth or who fail to "catch up" after hospital discharge, we increase its caloric density (eg, up to 27 kcal/ounce [0.9 kcal/mL]).
Duration — When the decision is made to feed an enriched diet after discharge, we generally continue the diet until a minimum of 40 weeks PMA and, ideally, until 48 or 52 weeks PMA, depending on the infant's growth trajectory. However, if the infant is directly breastfeeding and has adequate growth, we may stop the enriched feeds earlier, if desired by the caregivers, to avoid the need for bottle feeding.
TROUBLESHOOTING
Suboptimal growth — Multiple factors often contribute to poor growth in preterm infants, including genetics, social determinants of health, and medical comorbidities [1]. Nonetheless, assessing and optimizing caloric intake is an important step in management.
●Optimize breastfeeding – Mothers who give birth prematurely may have difficulty in establishing an adequate milk supply due to incomplete maturation of the mammary gland and less than optimal breast stimulation during feeding. Furthermore, the infant may have difficulty in the early phases of breastfeeding because their oro-buccal coordination and swallowing mechanisms may not be fully matured. Frequent breastfeeding and/or pumping is important to establish an adequate milk supply.
Preterm infants and their parents warrant direct assessment, support, and monitoring as they transition from enteral to oral feedings. For those who can breastfeed directly, the breastfeeding technique is similar to that for term infants, but the mother requires specialized instruction and support. (See "Breastfeeding the preterm infant".)
●Increase fortification or caloric density – For infants with suboptimal growth after NICU discharge (poor weight gain or persistent declines in weight Z-scores), we enrich the feeds by adding or increasing human milk fortifier or other supplement. The strategies are individualized depending on the infant's needs, feeding method (direct breastfeeding versus bottle), caregivers' preferences, and available resources, as outlined above. (See 'Enriched diet' above.)
Sucking or swallowing problems
●Poor oral feeding – Some preterm infants will struggle to maintain adequate enteral caloric intake due to poor oral feeding from developmental problems, oral aversion, or chronic medical problems. In particular, infants who were intubated and mechanically ventilated for a long time period may have difficulty with oral feeding, in part because of abnormal development of suck and swallow rhythms [33].
●Oromotor dysfunction – Neurologic impairment may also interfere with oral feeding and growth [34]. These patients may benefit from occupational or speech therapy to improve oral motor function. (See "Neonatal oral feeding difficulties due to sucking and swallowing disorders".)
In rare cases, infants with oral motor dysfunction may benefit from nasogastric or orogastric tube feeding while awaiting developmental improvement in the coordination required for oral feeding. All or a proportion of feedings may be provided by this route. In some cases, a gastrostomy may be preferred [34]. This approach may also decrease caloric expenditure in chronically ill infants, such as those with congenital heart disease or bronchopulmonary dysplasia (BPD).
In one report, fewer respiratory infections were seen in preterm infants discharged home with nursing care while they still required tube feedings compared with those who remained in the hospital until they could take full oral feeds [35]. There were no differences between the groups in infant health, surgical procedures, or medications. Despite these findings, the safety, efficacy, or cost/benefit ratio of gavage feedings at home is not clear and this technique must be used with caution [36].
Infants with complex comorbidities
●BPD – Growth faltering is common in infants with BPD, with reported rates of 30 to 67 percent [37]. Possible factors that contribute to poor growth in these infants include:
•Increased energy expenditure [38,39].
•Reduced fat absorption [40].
•Chronic hypoxia or suboptimal tissue oxygenation [41].
•Poor feeding endurance and performance with lower sucking pressure and decreased sucking frequency and swallowing in infants with severe BPD (requiring home oxygen therapy) compared with infants without BPD or with milder BPD [42].
Although poor growth is a common problem in infants with BPD, only one randomized controlled trial has evaluated the efficacy of nutrient-enriched formula for these infants [43]. In this study of 60 infants with BPD, patients were randomly assigned to one of two different 30 kcal/oz formulas until three months corrected age. Infants receiving protein- and mineral-enriched formula had better growth compared with control infants at three months corrected age. However, there was no difference in growth between the two groups at 12 months corrected age. It is unclear whether this means that the benefits of the formula were transient or whether the difference depends on continued administration of nutrient-enriched formula beyond three months corrected age.
In our institution, the nutritional management of these infants is highly individualized, especially in those with severe BPD. Fluid intake is largely determined by the baby's respiratory status. Enriched formulas or fortified human milk can be modified to meet the age-appropriate nutritional intakes of these infants with relatively high nutrient needs [44]. (See 'Enriched diet' above.)
●Intestinal failure – Infants with intestinal failure (primarily caused by short bowel syndrome after bowel resection for necrotizing enterocolitis) may have malabsorption due to insufficient intestinal absorptive area, which causes diarrhea and limits their ability to tolerate enteral feeds. In addition, if they have prolonged parenteral nutrition and enteral tube feeding, they may develop food aversion, which presents a further challenge to oral feeding. Prevention and management are discussed separately. (See "Management of short bowel syndrome in children".)
●Cholestatic liver disease – Infants with biliary atresia often have poor growth for several reasons, including anorexia, malabsorption due to insufficient intraluminal bile salts, and chronic liver inflammation. For infants with other types of cholestatic liver disease, including parenteral nutrition-associated liver disease (also known as intestinal failure-associated liver disease), the effects on growth depend on the severity and whether biliary function is impaired. (See "Biliary atresia" and "Intestinal failure-associated liver disease in infants".)
INTRODUCING SOLID FOODS —
Determining the optimal timing and composition of complementary feeding in preterm infants remains complex. Randomized trials comparing early (three or four months corrected age) versus late (five or six months corrected age) introduction of complementary feeding found no significant differences in growth outcomes at one year of age [45,46].
These findings suggest that optimizing growth should not be the primary rationale to introduce solid foods. An individualized approach is recommended, particularly for infants with weights between 3.5 and 5 kg or those at risk of nutrient deficits due to breastfeeding difficulties. If a preterm infant has achieved the same developmental milestones that a term infant needs to tolerate spoon-feeding of pureed foods, it seems reasonable to introduce solid foods as early as three months corrected age, disregarding the concept of chronologic age for this decision.
LONG-TERM OUTCOME
Growth — A preponderance of evidence suggests that individuals with very low birth weights (and/or who were born very prematurely) tend to have attenuated growth when measured in late childhood or early adulthood:
●Very low birth weight infants – At 20 years of age, adults who were very low birth weight (<1500 g) infants were twice as likely to have a height <3rd percentile than controls with normal birth weight (10 versus 5 percent) [47]. They are also shorter and have lower lean body mass up to 24 years of age [48].
●Extremely preterm infants:
•In the prospective EPICure cohort, individuals who were extremely preterm compared with age-matched controls were, on average, 4 cm shorter and 6.8 kg lighter and had a 1.5 cm smaller head circumference at 19 years of age [49].
•In a study from Australia of patients born from 1991 to 1992, the mean heights of extremely preterm survivors (n = 166) were less than those of term controls (n = 153) at all ages through 18 years of age (at 18 years of age, mean height Z-scores of -0.47±1.14 versus 0.26±0.98) [50]. The extremely preterm survivors were also lighter than term controls, though this difference decreased with age so that body mass index (BMI) Z-scores were similar for the two groups by 18 years of age. (See "Measurement of growth in children", section on 'Use of Z-scores'.)
•In a Swedish study of 123 children with a gestational age less than 26 weeks born between 1990 and 2002 [51]. The difference in mean Z-scores compared with normative standards decreased from when the patients were at term-adjusted age to follow-up at 10 years of age for weight (-3 versus -0.2) and height (-3.8 versus -0.7).
Further investigation is needed to better understand the factors that alter growth trajectories for children who are born extremely preterm and to develop targeted interventions to improve overall growth.
Associations with neurodevelopmental outcomes — Greater weight gain before reaching term appears to be associated with improved neurodevelopmental outcome [52]. This was illustrated in a study of 613 infants (gestational age below 33 weeks) that demonstrated greater weight gain, BMI, and head growth before 40 weeks postmenstrual age (PMA; ie, term) were associated with higher Bayley Mental and Psychomotor Developmental Indexes (MDI/PDI) scores at 18 months corrected age [53]. From term to four months corrected age, weight gain and linear growth were associated with higher PDI scores; however, there was not an associated improvement in either MDI or PDI scores with BMI. After four months corrected age, there was no association between any growth parameter and cognitive testing.
Greater weight, length, and head circumference by term-corrected age appears to be associated with improved neurodevelopmental outcomes [9,54]. In a retrospective study that examined the neurodevelopmental trajectories of 115 extremely preterm infants born at 22 to 28 weeks gestation, greater length was associated with higher developmental quotient scores between 1.5 and 3 years of corrected age [55].
SOCIETY GUIDELINE LINKS —
Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Nutrition support (parenteral and enteral nutrition) for neonates including preterm infants".)
SUMMARY AND RECOMMENDATIONS
●Rationale for monitoring growth – Preterm infants are often significantly underweight at the time of hospital discharge compared with infants born at term. At discharge, they remain at increased nutritional risk and merit close growth monitoring after hospital discharge. For postdischarge growth assessments, we use the Fenton growth charts up to 50 weeks postmenstrual age (PMA; ie, 10 weeks post-term) (figure 1A-B) and the World Health Organization (WHO) growth charts thereafter (females, males). We correct for gestational age until the infant is two years of age. (See 'Growth charts' above and 'Routine growth monitoring' above.)
●Feeding during the hospitalization – During the neonatal intensive care unit (NICU) hospitalization, most institutions provide an enriched diet for at-risk infants, as discussed separately. (See "Approach to enteral nutrition in the premature infant", section on 'Enriched diet'.)
●Feeds after hospital discharge – For infants who have required an enriched diet to achieve adequate growth rates while in the NICU, we suggest continuing enriched feeds after hospital discharge (Grade 2C). This typically includes those with birth weight <1500 g or poor growth (eg, decline in weight-for-age Z-scores greater than 1.2 between birth and 36 weeks PMA). An enriched diet is higher in energy and minerals compared with breast milk or term formula, but the nutrient content varies depending on how it is implemented (table 1). Continuing the enriched diet may modestly improve weight gain, and, theoretically, it may reduce the risk of osteopenia (although most benefits for bone health are during the NICU stay). Lower-risk infants who are initially discharged on a standard diet may be advanced to an enriched diet if they show signs of growth faltering. (See 'Indications' above.)
The implementation and duration of the enriched diet should be individualized based on the infant's prior and ongoing growth, whether they are breastfeeding directly, and underlying risk factors. The enriched diet is usually continued after NICU discharge until at least 40 weeks PMA and often longer, especially for formula-fed infants. (See 'Enriched diet' above.)
•Breastfed infants – For infants who are breastfeeding directly, several approaches can be used to provide the additional calories and minerals while promoting breastfeeding for its health benefits and convenience.
-Follow-up visits should include breastfeeding support, including encouraging frequent breastfeeding or pumping to promote milk supply, troubleshooting any difficulties, and referral to lactation support if needed. (See "Breastfeeding the preterm infant".)
-The strategy for providing an enriched diet should be individualized, depending on the infant's nutritional needs, direct breastfeeding, family's preferences, and available resources. (See 'Enriched diet' above.)
-Human milk-fed preterm infants should also receive iron and vitamin D supplementation as these two nutrients are inadequately supplied by human milk alone. (See 'Vitamin and mineral supplements' above.)
•Formula-fed infants – For formula-fed preterm infants, an enriched diet consists of a "postdischarge" preterm formula. The threshold for prescribing an enriched diet after NICU discharge varies, depending on the infant's birth weight and growth trajectory and cost considerations. We generally continue the postdischarge formula until 48 or 52 weeks PMA or until they have achieved adequate catchup growth. (See 'Enriched diet' above.)
●Special populations – Some infants are at increased risk of growth faltering after hospital discharge (see 'Troubleshooting' above):
•Infants with poor oral feeding may benefit from lactation support, additional enriched feeds, and, in some cases, detailed assessment by a specialist in sucking and swallowing disorders. (See "Breastfeeding the preterm infant" and "Neonatal oral feeding difficulties due to sucking and swallowing disorders".)
•Infants with bronchopulmonary dysplasia (BPD) may require additional feeding enrichment with protein and minerals to optimize growth. In our practice, the feeding of these infants needs to be individualized before hospital discharge to ensure adequate growth within the fluid intake limits imposed by the chronic lung disease.
