Small for gestational age preterm infants and later adiposity and height: A systematic review and meta-analysis

Short- and longer-term growth and development of fat mass in preterm infants

Preterm infants typically experience faster growth rates than term-born infants, often doubling their weight in six to eight weeks. However, many face challenges leading to growth faltering and suboptimal neurodevelopment. To achieve optimal growth, these infants often require fortified breastmilk or high-nutrient formula. While meeting nutrition and growth targets are essential, concerns arise about rapid postnatal growth during their catch-up phase, particularly regarding increased body fat at term-corrected age, possibly increasing their risk for obesity and chronic health conditions later. However, evidence suggests that although preterm infants may have higher body fat at term-corrected age, this difference diminishes by three months corrected age, aligning more closely with term-born infants. Systematic reviews of more than 20,000 individuals observed that small for gestational age preterm infants do not have higher adiposity in childhood and adulthood; rather, they exhibit lower body mass indexes, waist circumferences, similar body and visceral fat and blood pressure compared to their appropriate for gestational age preterm-born peers. Therefore, it is reassuring that promoting early growth in preterm infants does not necessitate a trade-off when it comes to supporting long-term metabolic outcomes versus neurodevelopment. Healthcare providers should encourage a responsive feeding approach, even in preterm infants, guided by infants' physiological needs, hunger and satiety once they exhibit feeding cues. This approach respects the child's developmental needs and encourages healthy eating habits, fostering positive parent-child feeding relationships, and ultimately allowing the child to grow and develop to their full potential without compromising their long-term health outcomes.

Amino acids and protein for preterm infants: How much and for what?

Protein and amino acids derived from protein digestion in the gastrointestinal tract or from intravenous infusions are fundamental for normal metabolism, growth, and neurodevelopmental outcomes in the fetus and the preterm infant of the same gestational age. Many studies support that at least 3.0-3.5 g/kg/day of protein or amino acids are needed to achieve normal nitrogen/protein balance and growth rates and the large fractional increase of lean mass in later gestation, either in the fetus or the preterm infant; this relationship is direct and linear. Faster growth rates in earlier gestation require more amino acids and protein than the late preterm or term infant. Protein synthesis and accretion also require sufficient energy, but above ∼120 kcal/kg/day, energy is largely diverted to fat production but not lean mass growth. Optimal IV amino acid solutions remain to be developed, and mature maternal milk and donor human milk require protein supplements to achieve appropriate protein balance and growth. Additional supplements of growth factors might augment increased protein intakes and fortifiers. While excess amino acid and/or protein intakes do not promote growth or development and might even be harmful, providing less than the amounts required guarantees poorer outcomes and should be avoided.

A review on lipid inclusion in preterm formula: Characteristics, nutritional support, challenges, and future perspectives

The lack of nutrient accumulation during the last trimester and the physiological immaturity at birth make nutrition for preterm infants a significant challenge. Lipids are essential for preterm infant growth, neurodevelopment, immune function, and intestinal health. However, the inclusion of novel lipids in preterm formulas has rarely been discussed. This study discusses specific lipid recommendations for preterm infants according to authoritative legislation based on their physiological characteristics. The gaps in lipid composition, such as fatty acids, triacylglycerols, and complex lipids, between preterm formulas and human milk have been summarized. The focus of this study is mainly on the vital roles of lipids in nutritional support, including long-chain polyunsaturated fatty acids, structural lipids, milk fat global membrane ingredients, and other minor components. These lipids have potential applications in preterm formulas for improving lipid absorption, regulating lipid metabolism, and protecting against intestinal inflammation. The lipidome and microbiome can be used to provide adequately powered evidence of the effects of lipids. This study proposes nutritional strategies for preterm infants and suggests approaches to enhance their lipid quality in preterm formula.

Association of Neonatal Morbidities and Postnatal Growth Faltering in Preterm Neonates

BACKGROUND/OBJECTIVES

Postnatal growth faltering (PGF) is a risk factor for adverse neurodevelopment in very preterm neonates. The aim of this retrospective study was to determine which infants' baseline characteristics, prenatal risk factors and neonatal morbidities are associated with two definitions of PGF: defined as loss of >2 weight z-scores (severe PGF) or as loss of >1 weight, length, and head circumference z-scores between birth and discharge (complex PGF); Methods: 146 premature newborns (<32 weeks of gestational age, <1500 g) were included in the study. Anonymized data including anthropometric measurements (weight, length, and head circumference), perinatal and neonatal data (demographics, maternal morbidities and previous pregnancies, and neonatal and perinatal morbidities) were extracted from the clinical electronic database. Changes in anthropometric age- and sex-specific z-scores using the Fenton 2013 preterm growth charts were calculated to diagnose severe PGF and complex PGF; Results: The incidence of severe PGF was 11% and complex PGF was 24%. Both PGF definitions were associated with bronchopulmonary dysplasia (BPD), severe retinopathy of prematurity (ROP), longer respiratory support, and longer hospital stay. Severe PGF was associated with surgical necrotizing enterocolitis at 25% vs. 1.5%, p = 0.001. Complex PGF was associated with severe brain injury at 51% versus 27%, p = 0.007. Complex PGF was more common in newborns born most prematurely, while severe PGF was more common in newborns born small for gestational age (SGA); Conclusions: Both severe and complex PGF are associated with several important neonatal morbidities, which might explain why growth faltering is associated with suboptimal neurodevelopment. Appropriate early identification of faltered growth may influence medical and nutrition interventions which in turn could improve the outcome of very preterm newborns.

What Is Normal Growth? Principles, Practicalities and Pitfalls of Growth Assessments in Infants and Children

BACKGROUND

Growth assessments are a pillar of public health surveillance, individual health screening, and clinical care. Normal growth is defined differently for individuals versus populations. The World Health Organization (WHO) growth standards were developed to describe the pattern of growth in healthy children without socioeconomic limitations whose mothers planned to breastfeed. The growth standards' cut-off points of ±2 standard deviations (z-scores) were defined for population assessments, based on attained size, to describe stunting and wasting at the lower end and overweight at the higher end. In a healthy population, one would expect 2.3% of the population to be above and below these cut-points. Higher child mortality rates associated with higher rates of stunting and wasting noted in observational studies validated these WHO cut-offs. There are knowledge gaps influencing the accuracy and effectiveness of growth assessments in individual children, posing challenges for health care providers.

SUMMARY

The principles of assessing normal growth in children and preterm infants are reviewed, along with pitfalls to be avoided. Growth is determined by genetics and modified by the interplay with nutritional, environmental, socioeconomic, and possibly intergenerational factors. This complexity is reflected at both the population and individual level. However, normal growth in an individual has unique-specific factors so requires a comprehensive assessment. Normal growth for an individual child could be defined as the progression of changes in anthropometric measurements to achieve the individual's genetic potential. A misdiagnosis of growth faltering can occur if infants and children are asses with one-time rather than serial measures, and if age is not corrected for prematurity. Health care provider sensitivity and cognizance when communicating about a child's size is important for parental reassurance and avoiding stigma and unnecessary pressures or restrictions around feeding.

Growth patterns by birth size of preterm children born at 24-29 gestational weeks for the first 3 years

BACKGROUND

Concerns are prevalent about preterm infant long-term growth regarding plotting low on growth charts at discharge, stunting, underweight, high body fat and subsequent cardiometabolic morbidities.

OBJECTIVES

To examine (a) longitudinal growth patterns of extremely and very preterm infants to 3 years corrected age (CA) (outcome), categorised by their birthweight for gestational age: small, appropriate and large for gestational age (SGA, AGA and LGA, respectively) (exposure); and (b) the ability of growth faltering (<-2 z-scores) to predict suboptimal cognitive scores at 3 years CA.

METHODS

Post-discharge head, length, weight and weight-4-length growth patterns of the PreM Growth cohort study infants born <30 weeks and < 1500 g, who had dietitian and multi-disciplinary support before and after discharge, were plotted against the World Health Organization growth standard. Infants with brain injuries, necrotising enterocolitis and bronchopulmonary dysplasia were excluded.

RESULTS

Of the included 405 infants, the proportions of infants with anthropometric measures > - 2 z-scores improved with age. The highest proportions <-2 z-scores for length (24.2%) and weight (24.0%) were at 36 gestational weeks. The proportion with small heads was low by 0 months CA (1.8%). By 3 years CA, only a few children plotted lower than -2 z-scores for length, weight-4-length and weight (<6%). After zero months CA, high weight-4-length and body mass index > + 2 z-scores were rare (2.1% at 3 years CA). Those born SGA had higher proportions with shorter heights (16.7% vs. 5.2%) and lower weights (27.8% vs. 3.5%) at 3 years CA compared to those born AGA. The ability of growth faltering to predict cognitive scores was limited (AUROC 0.42, 95% CI 0.39, 0.45 to 0.52, 95% CI 0.41, 0.63).

CONCLUSIONS

Although children born <30 weeks gestation without major neonatal morbidities plot low on growth charts at 36 weeks CA most catch up to growth chart curves by 3 years CA.

Does the evidence support in utero influences on later health and disease? A systematic review of highly cited Barker studies on developmental origins

The developmental origins of health and disease hypothesis proposes that early exposure to adverse conditions during fetal development and early life have strong detrimental consequences on long-term health and susceptibility to chronic diseases. We conducted a systematic review to critically appraise Barker's highest cited publications using the risk-of-bias assessment tool (ROBINS-I) and investigate effects of overadjustment by later body weight. Our findings revealed that all included studies displayed high risks of bias, with particular concerns regarding confounding (8/8), selection of reported results (8/8), classification of exposure (7/8), selection of participants (5/8) and high rates of missing data (ranged from 15 to 87%). Later body weight was over-adjusted in most (6/8) of the studies. As all studies displayed high bias risk due to confounding, missing data and overadjustment, evidence is insufficient to support causal relationships between low birthweight and adult disease, warranting caution in clinical application. PROTOCOL REGISTRATION: PROSPERO CRD42023433179.

Expected and Desirable Preterm and Small Infant Growth Patterns

Adequate nutrition is necessary for achieving optimal growth and neurodevelopment. Growth is a natural and expected process that happens concomitantly with rapid advancements in neurodevelopment. Serial weight, length, and head circumference growth measures are essential for monitoring development, although identifying pathological deviations from normal growth can pose challenges. Appropriate growth assessments require considerations that a range of sizes for length, head circumference, and weight are expected and appropriate. Because of genetic differences and morbidities, there is a considerable overlap between the growth of healthy infants and those with growth alterations. Parents tend to be over-concerned about children who plot low on growth charts and often need reassurance. Thus, the use of terms such as "poor" growth or growth "failure" are discouraged when growth is approximately parallel to growth chart curves even if their size is smaller than specific percentiles. No specific percentile should be set as a growth goal; individual variability should be expected. An infant's size at birth is important information that goes beyond the common use of prognostic predictions of appropriate compared with small or large for gestational age. The lower the birthweight, the lower the nutrient stores and the more important the need for nutrition support. Compared to term infants, preterm infants at term-equivalent age have a higher percentage of body fat, but this diminishes over the next months. Current research findings support expert recommendations that preterm infants should grow, after early postnatal weight loss, similar to the fetus and then term-born infants, which translates to growth approximately parallel to growth chart curves. There is no need for a trade-off between optimum cognition and optimum future health. Each high-risk infant needs individualized nutrition and growth assessments. This review aims to examine infant growth expectations and messaging for parents of preterm and term-born infants within the broader causal framework.

Effects of the COVID-19 pandemic on the rates of adverse birth outcomes and fetal mortality in Japan: an analysis of national data from 2010 to 2022

BACKGROUND

Although the coronavirus disease 2019 (COVID-19) pandemic affected trends of multiple health outcomes in Japan, there is a paucity of studies investigating the effect of the pandemic on adverse birth outcomes and fetal mortality. This study aimed to investigate the effect of the onset of the pandemic on the trends in adverse birth outcomes and fetal mortality using national data in Japan.

METHODS

We used the 2010-2022 birth and fetal mortality data from the Vital Statistics in Japan. We defined the starting time of the effect of the pandemic as April 2020, and the period from January 2010 to March 2020 and that from April 2020 to December 2022 were defined as the pre- and post- pandemic period, respectively. The rates of preterm birth, term low birth weight (TLBW), small-for-gestational-age (SGA), large-for-gestational-age (LGA), spontaneous fetal mortality, and artificial fetal mortality were used as outcomes. An interrupted time series analysis was conducted using monthly time series data of the outcomes to evaluate the effects of the pandemic. In addition, a modified Poisson regression model was used to evaluate the effects of the pandemic on these outcomes using individual-level data, and the adjusted risk ratio of the effect was calculated.

RESULTS

The adverse birth and fetal mortality outcomes showed a decreasing trend over the years, except for preterm birth and LGA birth rates, and SGA birth rates tended to reach their lowest values after the onset of the pandemic. The interrupted time series analysis revealed that the pandemic decreased preterm birth, TLBW, and SGA birth rates. In addition, the regression analysis revealed that the pandemic decreased the TLBW, SGA, and artificial fetal mortality rates.

CONCLUSIONS

Analyses performed using national data suggested that the pandemic decreased the TLBW and SGA rates in Japan.

Small for gestational age and anthropometric body composition from early childhood to adulthood: the Aboriginal Birth Cohort study

Background

In Australia the estimated rate of small for gestational age (SGA) births is 9% among non-Indigenous births compared to 14% among Aboriginal and Torres Strait Islanders. There is limited research investigating the effect of being born SGA on body composition later in life in Indigenous Australians.

Methods

Using data from the Aboriginal Birth Cohort longitudinal study, we compared the body composition of those born SGA to non-SGA by analysing anthropometric measures (height, weight, waist circumference, fat percentage [FAT%], body mass index [BMI], waist-to-height ratio, and A body shape index [ABSI]) collected at four follow-up periods (from childhood to adult). For cross-sectional analyses, linear regression models were employed to assess factors associated with anthropometric measures. For longitudinal analyses linear mixed models were employed to assess differences in anthropometric measures among SGA versus non-SGA individuals while adjusting for repeated measures.

Results

The analytic baseline cohort were those who participated in Wave 2 (n = 570). In cross-sectional analyses, across all waves those born SGA had smaller anthropometric z-scores compared to non-SGA individuals (β ranging from -0.50 to -0.25). Participants residing in urban environments were significantly larger in Waves 2 to 4 (β ranged 0.26 to 0.65). Those born SGA had higher ABSI scores in Waves 2 and 4 (β 0.26 and 0.37, respectively). In longitudinal analyses, those born SGA had smaller measures of body composition across the life course; these differences were larger in urban communities. In remote communities those born SGA had significantly higher ABSI scores during adolescence and young adulthood, and this difference was not observed in urban communities.

Conclusion

Indigenous Australians born SGA are smaller anthropometrically later in life compared to their non-SGA counterparts. In remote communities, those born SGA had higher levels of central adiposity compared to non-SGA.