Postnatal Growth Of Preterm Infants Research Articles

Socioeconomic disparities in the postnatal growth of preterm infants: a systematic review.

To determine the effect of parental socioeconomic status (SES) on the postnatal growth of preterm infants. A systematic review (PROSPERO registration CRD42020225714) of original articles from Medline, Embase, CINAHL Plus and Web of Science published 1946-2023 was undertaken. Studies were included if they reported anthropometric growth outcomes for preterm infants according to parental SES. Data extraction and assessments of bias and health equity impact were conducted using custom-designed forms. A narrative synthesis of twelve included studies was performed. Most infants were moderate to late preterm. The settings, growth outcomes, timings of growth measurement, and SES measures were heterogenous. Six studies demonstrated an adverse effect of low parental SES on the extrauterine growth of preterm infants, five studies showed no effect, and one study showed a potentially beneficial effect. All studies had a high risk of bias, especially confounding and selection bias. The health equity impact of included studies was largely negative. Limited and low-quality evidence suggests that socioeconomic minoritisation may adversely impact the growth of preterm infants, thereby widening existing socioeconomic health inequities. Observational studies informed by theorisation of the mechanistic pathways linking socioeconomic minoritisation to adverse postnatal growth are required to identify targets for intervention. Limited evidence suggests low parental socioeconomic status (SES) adversely affects the postnatal growth of preterm infants across different settings. Early growth of preterm infants predicts neurodevelopmental outcomes and the risk of cardiovascular and metabolic disease in adulthood. Systematic screening of over 15,000 articles identified only twelve studies which reported postnatal growth outcomes for preterm infants according to parental SES. The health equity impact of the included studies was systematically assessed, and found to be negative overall. This study highlights limitations in existing evidence on the association between parental SES and postnatal growth, and delineates avenues for future research.

Association between chronic diuretics and postnatal growth in preterm infants with bronchopulmonary dysplasia

BackgroundChronic diuretics such as thiazides and spironolactone are frequently used off-label in preterm infants with evolving or established bronchopulmonary dysplasia (BPD). Infants who are high risk for BPD are already predisposed to poor postnatal growth and the effect of chronic diuretics on postnatal growth is not well studied. ObjectiveExploratory study to determine the association between chronic diuretic exposure and short-term postnatal growth in preterm infants born at less than ≤ 29 weeks gestational age (GA). MethodsSingle-center retrospective cohort study in a level IV neonatal intensive care unit over a 2-year period (2021–22). Eligible infants exposed to chronic diuretics > 5 days for BPD (diuretic group) were compared to infants who were not (non-diuretic group). ResultsIn total, 53 infants (19 diuretic, and 35 non-diuretic group) were identified. The GA (25.3 vs 27.0 weeks) and birth weight (780 vs. 995 gs) were significantly lower in diuretic vs. non-diuretic group (p = 0.01). Diuretic group had higher intubation rate at birth, more days on non-invasive ventilation, higher incidence of moderate/severe BPD, and longer hospital stay (all p < 0.05). The GA adjusted z-scores for weight, length, and head circumference at birth, at 36-week corrected GA, and at discharge were similar in both groups. Also, the z-score change from birth at 36-week corrected GA, and at discharge were similar in both groups. There was no significant short-term change in weight z-score in the 2 weeks following chronic diuretic exposure. ConclusionsChronic diuretic exposure has no significant association with short-term postnatal growth in preterm infants.

Differences in Postnatal Growth of Preterm Infants in Northern China Compared to the INTERGROWTH-21st Preterm Postnatal Growth Standards: A Retrospective Cohort Study

BackgroundThe INTERGROWTH-21st preterm postnatal growth standards (IPPGS) have increasingly been used to evaluate the growth of preterm infants worldwide. However, the validity of IPPGS's application to specific preterm populations remains controversial. This retrospective cohort study aimed to formulate reference growth charts for a preterm cohort in northern China and compare them to the IPPGS.MethodsA total of 1,827 healthy preterm infants with follow-up visits before 70 weeks of postmenstrual age (PMA) were retrospectively sampled from a preterm cohort (N = 2,011) born between 1 January 2011 and 28 February 2021, at the First Affiliated Hospital of Shandong First Medical University. Using the Generalized Additive Models for Location, Scale, and Shape method, 5,539 sets of longitudinal data were used to construct percentile and Z-score charts of length, weight, and head circumference (HC) at 40–64 weeks of PMA. Z-scores of length, weight, and HC (LAZ, WAZ, and HCZ) before 64 weeks were calculated using the IPPGS. Differences in the 50th percentile values between preterm infants and IPPGS (dLength, dWeight, and dHC) were calculated. Z-scores were assigned to six PMA clusters: 40–44, 44–48, 48–52, 52–56, 56–60, and 60–64 weeks for comparison between sexes.ResultsFor eligible infants, the mean PMA and weight at birth were 33.93 weeks and 2.3 kg, respectively. Boys, late preterm infants, twins, and infants with exclusively breastfeeding accounted for 55.8, 70.6, 27.8, and 45.9%, respectively. Compared to IPPGS, preterm infants were longer and heavier, especially for dLength in girls (range, 2.19–2.97 cm), which almost spanned the 50th and 90th percentiles of IPPGS. The dHC tended to narrow with PMA for both sexes. The mean LAZ, WAZ, and HCZ of both sexes at all PMA clusters were >0, especially for LAZ and WAZ (about 1.0 relative to IPPGS), indicating higher levels than the IPPGS at 40–64 weeks. Girls had larger LAZ at each PMA cluster, larger WAZ at 40–44 weeks, and lower HCZ after 56 weeks than boys. HCZ declined with PMA for both sexes.ConclusionPostnatal growth of this preterm cohort was considerably higher than that of the IPPGS at 40–64 weeks of PMA with sex differences.

Comparação das curvas de intergrowth-21st e de Fenton para avaliação de recém-nascidos prematuros

Abstract Objectives: to compare the intrauterine and postnatal growth of preterm infants according to the Intergrowth-21st and Fenton curves. Methods: study carried out in a maternity hospital, reference in high-risk pregnancy, with preterm infants born in 2018 who were hospitalized in the neonatal units of the institution. Preterm newborns weighed at least twice after birth were included in the sample and those that were syndromic, malformed or presented fluid retention were excluded. Proportions and means were compared using Pearson’s chi-square and Student’s t tests for paired samples, respectively. The McNemar test was used to compare categorical variables and the Kappa test to verify the degree of agreement between birth weight classifications obtained by the curves. Results: one hundred and fifty three infants with a median gestational age of 34.4 weeks were included. The incidences of the categories of nutritional status at birth did not differ between the curves. There was perfect agreement between the curves, except when newborns born under 33 weeks of gestational age were evaluated, in which case the agreement was substantial. About 21% of the babies classified as small for gestational age (SGA) by Intergrowth-21st were adequate for gestational age (AGA) according to Fenton and, on average, 20% of cases that had postnatal growth restriction (PNGR) according to Fenton standards were categorized as adequate weight by Intergrowth-21st. Postnatal weight classifications obtained by the evaluated curves had perfect agreement. Conclusions: the differences in theclassifications found between the charts reveal the importance of choosing the growth curve for monitoring preterm infants since behaviors based on their diagnoses can impact the life of this population.

Retinopathy of Prematurity Requiring Treatment Is Closely Related to Head Growth during Neonatal Intensive Care Unit Hospitalization in Very Low Birth Weight Infants

Background: Retinopathy of prematurity (ROP) is caused by prenatal sensitization and postnatal insults to the immature retina. This process can be associated with the postnatal growth of preterm infants. We investigated whether ROP requiring treatment was associated with the postnatal growth failure of very low birth weight (VLBW) infants. Method: From a cohort of VLBW infants (birth weight <1,500 g) registered in the Korean Neonatal Network from January 2013 to December 2017, 3,133 infants with gestational age (GA) between 24 and 28 weeks were included in the study. Postnatal growth failure was defined when the change in each anthropometric z-score between birth and discharge was <10th percentile of the total population. Propensity score matching (PSM) at 1:1 was performed to match the distribution of GA and postnatal morbidities between infants with and without ROP requiring treatment. Prenatal factors and ROP were analyzed by conditional logistic regression. Results: Of 3,133 enrolled infants, 624 (19.9%) were diagnosed with ROP requiring treatment. After PSM, ROP requiring treatment was associated with postnatal growth failure assessed by head circumference (adjusted odds ratio [aOR] 1.91, 95% confidence interval [CI] 1.18–3.09), but not weight (aOR 1.45, 95% CI 0.97–2.17) and length (aOR 1.21, 95% CI 0.81–1.82). Conclusion: ROP requiring treatment was associated with poor head circumference growth, not with weight and length. Our findings suggest that ROP requiring treatment and poor head growth during NICU hospitalization are fundamentally related.

Fenton vs. Intergrowth-21st: Postnatal Growth Assessment and Prediction of Neurodevelopment in Preterm Infants.

Although the survival rate of preterm infants has improved over the years, growth failure and associated impaired neurodevelopmental outcome remains a significant morbidity. Optimal nutrition plays an important role in achieving adequate postnatal growth. Accurate growth monitoring of preterm infants is critical in guiding nutritional protocols. Currently, there is no consensus regarding which growth assessment tool is suitable for monitoring postnatal growth of preterm infants to foster optimal neurodevelopmental outcomes while avoiding future consequences of aggressive nutritional approaches including increased risk for cardiovascular disease and metabolic syndrome. A retrospective single center cohort study was conducted to compare the performance of two growth-assessment tools, Fenton and Intergrowth-21st (IG-21st) in the classification of size at birth, identification of impaired growth and predicting neurodevelopment. A total of 340 infants with mean gestational age of 30 weeks were included. Proportion of agreement between the two tools for identification of small for gestational age (SGA) was high 0.94 (0.87, 0.1) however, agreement for classification of postnatal growth failure at discharge was moderate 0.6 (0.52, 0.69). Growth failure at discharge was less prevalent using IG-21st. There was significant association between weight-based growth failure and poor neurodevelopmental outcomes at 12 and 24 months of age.

Growth patterns of preterm infants in Korea.

With advancements in neonatal care and nutrition, the postnatal growth of preterm infants has improved; however, it remains an issue. Accurate assessments of growth using a standardized reference are needed to interpret the intrauterine and postnatal growth patterns of preterm infants. Growth in the earlier periods of life can contribute to later outcomes, and the refinement of postnatal growth failure is needed to optimize outcomes. Catchup growth occurs mainly before discharge and until 24 months of age, and very low birth weight infants in Korea achieve retarded growth later in life. Knowing an infant’s perinatal history, reducing morbidity rates during admission, and performing regular monitoring after discharge are required. Preterm infants with a lower birth weight or who were small for gestational age are at increased risk of poor neurodevelopmental outcomes. Furthermore, poor postnatal growth is predictive of adverse neurodevelopmental outcomes. Careful monitoring and early intervention will contribute to better development outcomes and national public health improvements.

Pre-pregnancy body mass index, gestational weight gain and postnatal growth in preterm infants.

To evaluate associations between pre-pregnancy body mass index (BMI), gestational weight gain (GWG), and postnatal growth in preterm infants. A cohort study of 14,962 births < 32 weeks' gestation. We used multivariable linear regression to assess associations between maternal BMI or GWG (models stratified by BMI) and infant postnatal growth, defined as the difference between discharge and birth weight Z-scores based on Fenton or INTERGROWTH-21st growth charts. For BMI, obesity class 2 was positively associated with postnatal growth using the Fenton chart. Using INTERGROWTH-21st, inadequate or excessive GWG in women with underweight or obesity class 3 were associated with postnatal growth in different directions. Excessive GWG in women with normal weight was negatively associated with postnatal growth defined by Fenton. Some categories of BMI and GWG were modestly associated with postnatal growth in preterm infants. Results were inconsistent within and between the INTERGROWTH-21st standard and Fenton growth reference.

Postnatal growth of preterm infants during the first two years of life: catch-up growth accompanied by risk of overweight

BackgroundEarly postanal growth of preterm infants has many effects on early and late health. However, evidence on growth pattern in Chinese preterm infant population during early life is insufficient. This study aims to describe the growth trajectory, catch-up growth, and risk of overweight of preterm infants during the first 2 years of life in a Chinese community population.MethodsAll preterm infants (n = 10,624) received routine childcare in one primary maternal and child healthcare network in 8 years were included. Body weight and length/height at corrected age (CA) 40 weeks, CA 3 months, 6 months, 9 months, 12 months, 18 months, and 24 months were extracted and converted to z-scores based on the World Health Organization (WHO) standards. According to the intrauterine growth status, infants were divided into small for gestational age (SGA), appropriate for gestational age (AGA), and large for gestational age (LGA) infants. Changes of z-score were used to describe the growth velocity. Generalized estimating equation (GEE) model was used to analyze growth trajectory trends over time.ResultsBody weight and length/height were overall above the WHO standards during the first 2 years of life. Z-score increased significantly by 0.08 (95% CI: 0.06–0.10) in weight and 0.07 (95% CI: 0.04–0.09) in length/height from CA 40 weeks to 3 months and then levelled off until CA 24 months after adjustment. Almost 90% of AGA and LGA infants achieved growth targets (≥25th percentile of WHO standards), and over 85% of SGA infants achieved catch-up growth (≥10th percentile of WHO standards) before CA 24 months. However, the risk of overweight appeared during this period, with the proportion of infants with the risk of overweight being at the peak at CA 3 months (25.6% of all preterm infants and 39.4% of LGA infants). Growth trajectories of SGA showed increasing trends, but those of LGA showed decreasing trends during the first 2 years.ConclusionsBody weight and length/height of preterm infants are above the WHO standards in the Chinese community population during the first 2 years of life. Catch-up growth is accompanied by risk of overweight as early as CA 3 months.(349 words)

Comparison of Postnatal Growth Charts of Singleton Preterm and Term Infants Using World Health Organization Standards at 40-160 Weeks Postmenstrual Age: A Chinese Single-Center Retrospective Cohort Study.

There remains controversy regarding whether the growth charts constructed from data of term infants, such as those produced by the World Health Organization (WHO) standards, can appropriately evaluate the postnatal growth of preterm infants. This retrospective cohort study, conducted in the First Affiliated Hospital of Shandong First Medical University in Jinan China, aimed to compare the postnatal growth charts of singleton preterm and term infants using WHO standards at 40–160 weeks postmenstrual age (PMA). A total of 5,459 and 15,185 sets of longitudinal measurements [length/height, weight, head circumference (HC), and body mass index (BMI)] from birth to 160 weeks PMA were used to construct growth charts for 559 singleton preterm (mean PMA at birth, 33.84 weeks) and 1,596 singleton term infants (born at 40 weeks PMA), respectively, using the Generalized Additive Models for Location, Scale, and Shape (GAMLSS) method. Z-scores (prematurity corrected) were calculated using WHO Anthro software. Compared to WHO standards, all parameters of preterm infants were increased, especially in terms of length/height and weight; the gap between the two almost spanned two adjacent centile curves. Compared to term controls, the length/height, weight, and BMI of preterm infants were higher at 40 weeks PMA, surpassed by term infants at 52–64 weeks PMA, and quite consistent thereafter. The HC of preterm infants at 40–160 weeks PMA was quite consistent with both term controls and the WHO standards. The Z-scores for length/height, weight, and BMI of preterm infants relative to the WHO standards gradually decreased from 1.20, 1.13, and 0.74 at 40–44 weeks PMA to 0.67, 0.42, and 0.03 at 132–160 weeks PMA, respectively; Z-scores for HC of preterm infants rapidly decreased from 0.73 to 0.29 at 40–50 weeks PMA, and then fluctuated in the range of 0.08–0.23 at 50–160 weeks PMA. Preterm infants had higher growth trajectories than the WHO standards and similar but not identical trajectories to term infants during the first 2 years of life. These findings reemphasize the necessity of constructing local growth charts for Chinese singleton preterm infants.

Medical outcome and post-natal growth approach of premature infant in ambulatory follow-up in N’Djamena (Chad)

The survival of preterm infants depends on the health development level of each country and those who survive need a closer follow-up after the discharge. The objective of this study was to evaluate morbidity, mortality and post-natal growth of preterm infants in the first six-month of life in a low income country. This was a longitudinal study from May 2015 to June 2016 in the pediatrics department of the Mother and Child Teaching Hospital of N’Djamena. It involved all preterm infants hospitalized during six months of inclusion period and followed in this structure. The morbidity rate was 26.9% in the first month of follow-up. The more frequent pathologies were acute respiratory infections (37%), functional digestive troubles (33%) followed by anemia and malaria (15%). Eight infants (11.9%) had been hospitalized again with 3 deaths recorded (4.5%). The growth was regular but the measures were mostly less than -2 Z score. Average weight was 6165.6 g at 6 months; average height: 60.72 cm and average head circumference: 41.62 cm. Adjustment of cranial circumference was earliest with 53 and 87% of normal value at 3 and 6 months respectively. The improvement of care of preterm infants would need the development of perinatalogy and follow-up network.

Effect of Nutritional Intervention by the Nutrition Support Team on Postnatal Growth in Preterm Infants

Effect of Nutritional Intervention by the Nutrition Support Team on Postnatal Growth in Preterm Infants

The effect of multi-disciplinary nutritional support team activities on the growth of preterm infants in neonatal intensive care unit

Rationale: Preterm infants are high risk groups that are prone to lack of nutrition compared to the nutritional requirements at the beginning of their birth. This study was done to investigate whether multidisciplinary nutritional support team activities (MNSTA) improve to postnatal growth of preterm infants at 36 weeks corrected age(CA).

Postnatal growth of preterm infants 24 to 26 weeks of gestation and cognitive outcomes at 2 years of age.

Background:Weight z scores at 36 weeks of postmenstrual age (PMA) define postnatal growth failure (PGF) and malnutrition. This study aimed to determine weight z scores at 36 weeks PMA that are associated with adverse cognitive outcomes at 2 years of age.Methods:In this retrospective cohort study, 350 infants 24 to 26 weeks of gestation born between 2006 and 2014 and followed at 2 years were included. Weight z scores at birth and at 36 weeks PMA were calculated using the INTERGROWTH-21st growth curves. The primary outcome was cognitive delay at 2 years of age (Bayley-III cognitive score < 85).Results:Neither the traditional definition of PGF (z score below −1.3) nor the recently proposed definition of malnutrition (z score decline of 1.2 or greater) was associated with cognitive delay. Both a weight z score below −1.0 at 36 weeks PMA (RR: 1.65; 95% CI: 1.10 - 2.49; p <0.05) and a decline below −1.0 in weight z score from birth to 36 weeks PMA (RR: 1.40; 95% CI: 1.00 – 1.94; p <0.05) were associated with a higher risk of cognitive delay.Conclusion:With optimal cutoffs, INTERGROWTH-21st weight z scores can predict the risk of cognitive delay.

Extrauterine growth restriction in extremely preterm infants based on the Intergrowth-21st Project Preterm Postnatal Follow-up Study growth charts and the Fenton growth charts.

Growth charts are essential for monitoring the postnatal growth of preterm infants. The preterm postnatal follow-up study (PPFS) of the Intergrowth-21st Project provides new growth standards based on a longitudinal study. This study was conducted to investigate the prevalence of extrautrine growth restriction (EUGR) and the associated factors of EUGR in preterm infants, using the PPFS charts and the Fenton charts. Data of 1,356 infants with gestational age (GA) less than 28 weeks from the Korean Neonatal Network were analysed. The prevalence of small for gestational age (SGA) of weight and length was higher with the Intergrowth charts than with the Fenton charts. EUGR in weight and length was more prevalent when using the Fenton charts. Multivariate analysis showed that low GA, high birthweight z score, male, treated patent ductus arteriosus (PDA), necrotizing enterocolitis, intraventricular haemorrhage and duration of parenteral nutrition (PN) were associated with EUGR in weight by the Intergrowth charts. High birthweight z score, treated PDA and PN duration were associated with EUGR defined by the Fenton charts.Conclusion: Compared to the Fenton charts, SGA was more defined and EUGR was less prevalent in extremely low gestational infants, while EUGR defined by the Intergrowth charts categorized infants with adverse clinical courses more elaborately.What is Known:• Preterm infants are at risk of postnatal growth restriction (PGR), although optimal postnatal growth is important for the long-term outcomes.• Growth charts are essential tools to monitor the postnatal growth of preterm infants.What is New:• PGR of weight and length were less defined with the Intergrowth charts than the Fenton charts.• PGR defined by the Intergrowth preterm postnatal follow-up study (PPFS) chart categorized preterm infants with morbidities more elaborately than the Fenton charts.Electronic supplementary materialThe online version of this article (10.1007/s00431-020-03796-0) contains supplementary material, which is available to authorized users.

Is the Intrauterine INTERGROWTH-21 Growth Curve Better Than Fenton’s for the Classification at Birth and Prediction of Postnatal Growth in Preterm Infants?

To compare the classification of the adequacy of birth weight for gestational age applying INTERGROWTH-21 (IG-21) and Fenton growth curves in preterm infants, and to relate this classification to the nutritional status at 12months corrected age. This is a retrospective study with 173 preterm infants aged between 26 and 33weeks. Data was collected on maternal health conditions, birth and gestational age anthropometric information, and anthropometry (weight, height, and head circumference) at 12months corrected age. The mean birth weight and gestational age were 1151.4 ± 227.2g and 30.2 ± 2.4weeks, respectively. Using percentiles of IG-21 and Fenton curves, the proportion of SGA and LGA preterm infants was 39.2% vs. 35.2%, and 3.5% vs. 3.5%, respectively (p = 0.520). At 12months corrected age, short stature, overweight, and thinness were observed in 33.5%, 9.9%, and 11% of preterm infants, respectively. The ROC curve evidenced that the IG-21 was slightly better than Fenton to predict short stature (AUC = 0.626, 95% CI 0.537-0.715 and AUC = 0.600, 95% CI 0.506-0.694) and overweight (AUC = 0.648, 95% CI 0.527-0.769 and AUC = 0.618, 95% CI 0.486-0.750) at 12months corrected age. In contrast, the ROC curve did not show an association of IG-21 and Fenton percentiles with thinness. This study showed that IG-21 and Fenton were similar for the classification of birth weight for gestational age in preterm infants. IG-21 was slightly better than Fenton to predict overweight and short stature in preterm infants at 12months corrected age.

Extrauterine growth restriction in very preterm infant: etiology, diagnosis, and 2-year follow-up.

In very-preterm small-for-gestational-age (SGA) infants, long-term postnatal growth is confused with extrauterine growth restriction (EUGR). We aimed to document EUGR in SGA infants and in non-SGA infants ("true-EUGR") and its relationship with fetal, maternal, and neonatal etiological factors. Four hundred seventy-nine very-preterm infants (< 32weeks) born between 2003 and 2014 and attending the follow-up clinic were included. INTERGROWTH-21st preterm postnatal growth standards in conjunction with WHO Child Growth Standards were used to judge the postnatal growth patterns. EUGR was defined as weight < 10th percentile according to the sex at 36-34weeks postmenstrual age, usually at discharge. Catch-up was evaluated at 2-2.5years. Low-weight-for-age (wasting), low-length-for-age (stunting), and low-head-circumference-for-age were diagnosed if the z-scores were below - 2 SD. Logistic regression analysis estimated the association between the risk factors and EUGR, according to the SGA status at birth. Overall, EUGR occurred in 51% at 36-34 postmenstrual weeks and 21% at 2-2.5years. However, among 411 non-SGA infants, "true-EUGR" rates were 43% and 15%, respectively.Conclusion: By 2-2.5years of age, a "true-EUGR" of 15% can be expected and only the head circumference normalizes in SGA infants. Low birth weight, hyaline membrane disease, bronchopulmonary dysplasia, and male sex were associated with "true-EUGR." What is Known: • Fetal, neonatal, or postnatal charts have been considered to monitor the postnatal growth of preterm infants. • This selection influences the diagnosis of "extrauterine growth restriction" (EUGR) and the clinical strategies used. What is New: • Extrauterine growth restriction (EUGR) in small-for-gestational-age (SGA) infants can not be considered a true EUGR but a postnatal evolution of fetal growth restriction. • Preeclampsia, low gestational age, severe neonatal morbidity and male sex are independently associated with EUGR in non-SGA infants (named "true-EUGR"), which can be expected in 15% of very preterm infants by 2-2.5 years of age.

Updates on Assessment and Monitoring of the Postnatal Growth of Preterm Infants.

Assessing and monitoring the physical growth of preterm infants is fundamental to NICU care. The goals of nutritional care are to approximate the growth and body composition of the healthy fetus and to support optimal brain development while minimizing future cardiometabolic risk. Both poor and excessive growth predict adverse long-term health outcomes. Growth curves are clinical tools used to assess the preterm infant's growth status. Several growth curves for preterm infants were developed in the past decade. To use them effectively, clinicians need to understand how each growth curve was developed; the underlying reference population; intended use; and strengths and limitations. Intrauterine growth curves are references that use size at birth to represent healthy fetal growth. These curves serve 2 purposes-to assign size classifications at birth and to monitor postnatal growth. The INTERGROWTH-21 st preterm postnatal growth standards were developed to compare the postnatal growth of preterm infants to that of healthy preterm infants rather than the fetus. Individualized weight growth curves account for the water weight loss that frequently occurs after birth. In addition, body mass index (BMI) curves are now available. In this review, we discuss the main characteristics of growth curves used for preterm infants as well as the use of percentiles, z scores, and their change over time to evaluate size and growth status. We also review the differences in body composition between preterm infants at term-equivalent age and term-born infants and the potential role of monitoring proportionality of growth using BMI curves.

Prolonged ventilation and postnatal growth of preterm infants.

Background Extremely premature infants often need invasive respiratory support from birth, but have low nutritional reserves and high metabolic demands. Our aim was to determine if there was a relationship between prolonged ventilation and reduced postnatal growth in such infants. Methods A retrospective, observational study was undertaken. Data from infants born at less than 28 weeks of gestational age and ventilated for 7 days or more were collected and analysed including gestational age, gender, birth and discharge weight, birth and discharge head circumference, days of invasive mechanical ventilation and use of postnatal corticosteroids. The duration of invasive mechanical ventilation and the differences in weight (ΔWz) and head circumference (ΔHz) z-score from birth to discharge were calculated. Results Fifty-five infants were studied with a median [interquartile range (IQR)] gestational age at birth of 25.3 (24.3-26.7) weeks and birth weight of 0.73 (0.65-0.87) kg. The median duration of mechanical ventilation was 45 (33-68) days. Both ΔWz and ΔHz were significantly negatively correlated to the number of invasive mechanical ventilation days (P = 0.01 and P = 0.03, respectively), but not to the use of postnatal corticosteroids. Conclusion Poor postnatal growth is significantly negatively associated with a longer duration of mechanical ventilation in extremely prematurely born infants.

Postnatal growth in preterm infants during the first year of life: A population-based cohort study in China.

In preterm infants (i.e. the gestational age less than 37 weeks), postnatal growth remains a concern. This study used multicenter longitudinal data from China’s Under 5 Child Nutrition and Health Surveillance System to investigate the postnatal growth in the weight and length of preterm infants. Gender-stratified differences in weight and length were assessed between preterm and term infants. 1221 preterm infants and 1221 matched term infants were included. The rates of growth in weight and length in preterm infants was greater than those in term infants, especially from the first to sixth month. The rates were higher in males compared to females in the first 3 months. The differences of weight and length between preterm and term infants decreased with increasing age, however, these measurements did not reach the level of their term peers until 12 months before adjusting for gestational age. The median values of weight and length were even larger in preterm infants in the first month after adjusting for gestational age.