Early life factors predict abnormal growth and bone accretion at prepuberty in former premature infants with/without neonatal dexamethasone exposure

Invited Mini Review Metabolic Bone Disease of Prematurity: Overview and Practice Recommendations

Metabolic bone disease of prematurity (MBDP) is defined by undermineralization of the preterm infant skeleton arising from inadequate prenatal and postnatal calcium (Ca) and phosphate (PO4) accretion. Severe MBDP can be associated with rickets and fractures. Despite advances in neonatal nutrition, MBDP remains prevalent in premature infants due to inadequate mineral accretion ex utero. There also remain significant knowledge gaps regarding best practices for monitoring and treatment of MBDP among neonatologists and pediatric endocrinologists. Preventing and treating MBDP can prevent serious consequences including rickets or pathologic fractures. Postnatal monitoring to facilitate early recognition of MBDP is best done by first-tier laboratory screening by measuring serum Ca, phosphorus, and alkaline phosphatase to identify infants at risk. If these laboratories are abnormal, further studies including assessing parathyroid hormone and/or tubular resorption of PO4 can help differentiate between Ca and PO4 deficiency as primary etiologies to guide appropriate treatment with mineral supplements. Additional research into optimal mineral supplementation for the prevention and treatment of MBDP is needed to improve long-term bone health outcomes and provide a fuller evidence base for future treatment guidelines. Metabolic bone disease of prematurity (MBDP) is defined by undermineralization of the preterm infant skeleton arising from inadequate prenatal and postnatal calcium (Ca) and phosphate (PO4) accretion. Severe MBDP can be associated with rickets and fractures. Despite advances in neonatal nutrition, MBDP remains prevalent in premature infants due to inadequate mineral accretion ex utero. There also remain significant knowledge gaps regarding best practices for monitoring and treatment of MBDP among neonatologists and pediatric endocrinologists. Preventing and treating MBDP can prevent serious consequences including rickets or pathologic fractures. Postnatal monitoring to facilitate early recognition of MBDP is best done by first-tier laboratory screening by measuring serum Ca, phosphorus, and alkaline phosphatase to identify infants at risk. If these laboratories are abnormal, further studies including assessing parathyroid hormone and/or tubular resorption of PO4 can help differentiate between Ca and PO4 deficiency as primary etiologies to guide appropriate treatment with mineral supplements. Additional research into optimal mineral supplementation for the prevention and treatment of MBDP is needed to improve long-term bone health outcomes and provide a fuller evidence base for future treatment guidelines.

Preterm birth and exercise capacity: what do we currently know?

Objectives

The long-term cardiopulmonary outcomes following preterm birth during the surfactant era remain unclear. Respiratory symptoms, particularly exertional symptoms, are common in preterm children. Therefore, cardiopulmonary exercise testing may provide insights into the pathophysiology driving exertional respiratory symptoms in those born preterm. This review aims to outline the current knowledge of cardiopulmonary exercise testing in the assessment of children born preterm in the surfactant era.

Design

This study is a narrative literature review.

Methods

Published manuscripts concerning the assessment of pulmonary outcomes using cardiopulmonary exercise testing in preterm children (aged <18 years) were reviewed. Search terms related to preterm birth, bronchopulmonary dysplasia, and exercise were entered into electronic databases, including Medline, PubMed, and Google Scholar. Reference lists from included studies were scanned for additional manuscripts.

Results

Preterm children have disrupted lung development with significant structural and functional lung disease and increased respiratory symptoms. The association between these (resting) assessments of respiratory health and exercise capacity is unclear; however, expiratory flow limitation and an altered ventilatory response (rapid, shallow breathing) are seen during exercise. Due to the heterogeneity of participants, treatments, and exercise protocols, the effect of the aforementioned limitations on exercise capacity in children born preterm is conflicting and poorly understood.

Conclusion

Risk factors for reduced exercise capacity in those born preterm remain poorly understood; however, utilizing cardiopulmonary exercise testing to its full potential, the pathophysiology of exercise limitation in survivors of preterm birth will enhance our understanding of the role exercise may play. The role of exercise interventions in mitigating the risk of chronic disease and premature death following preterm birth has yet to be fully realized and should be a focus of future robust randomized controlled trials.

Hormonal Determinants of Growth and Weight Gain in the Human Fetus and Preterm Infant

The factors controlling linear growth and weight gain in the human fetus and newborn infant are poorly understood. We review here the changes in linear growth, weight gain, lean body mass, and fat mass during mid- and late gestation and the early postnatal period in the context of changes in the secretion and action of maternal, placental, fetal, and neonatal hormones, growth factors, and adipocytokines. We assess the effects of hormonal determinants on placental nutrient delivery and the impact of preterm delivery on hormone expression and postnatal growth and metabolic function. We then discuss the effects of various maternal disorders and nutritional and pharmacologic interventions on fetal and perinatal hormone and growth factor production, growth, and fat deposition and consider important unresolved questions in the field.

Dexamethasone, Prednisolone, and Methylprednisolone Use and 2-Year Neurodevelopmental Outcomes in Extremely Preterm Infants

IMPORTANCE

Practice variability exists in the use of corticosteroids to treat or prevent bronchopulmonary dysplasia in extremely preterm infants, but there is limited information on longer-term impacts.

OBJECTIVE

To describe the use of corticosteroids in extremely preterm infants and evaluate the association with neurodevelopmental outcomes.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study was a secondary analysis of data from the Preterm Erythropoietin Neuroprotection (PENUT) randomized clinical trial, conducted at 19 participating sites and 30 neonatal intensive care units (NICUs) in the US. Inborn infants born between 24 0/7 and 27 6/7 weeks gestational age between December 2013 and September 2016 were included in analysis. Data analysis was conducted between February 2021 and January 2022.

EXPOSURES

Cumulative dose of dexamethasone and duration of therapy for dexamethasone and prednisolone or methyl prednisolone were evaluated.

MAIN OUTCOMES AND MEASURES

Demographic and clinical characteristics were described in infants who did or did not receive corticosteroids of interest and survived to discharge. Neurodevelopmental outcomes at 2 years of age were evaluated using the Bayley Scales of Infant Development-Third Edition (BSID-III) at corrected age 2 years.

RESULTS

A total of 828 extremely preterm infants (403 [49%] girls; median [IQR] gestational age, 26 [25-27] weeks) born at 19 sites who survived to discharge were included in this analysis, and 312 infants (38%) were exposed to at least 1 corticosteroid of interest during their NICU stay, including 279 exposed to dexamethasone, 137 exposed to prednisolone or methylprednisolone, and 79 exposed to both. Exposed infants, compared with nonexposed infants, had a lower birth weight (mean [SD], 718 [168] g vs 868 [180] g) and were born earlier (mean [SD] gestational age, 25 [1] weeks vs 26 [1] weeks). The median (IQR) start day was 29 (20-44) days for dexamethasone and 53 (30-90) days for prednisolone or methylprednisolone. The median (IQR) total days of exposure was 10 (5-15) days for dexamethasone and 13 (6-25) days for prednisolone or methylprednisolone. The median (IQR) cumulative dose of dexamethasone was 1.3 (0.9-2.8) mg/kg. After adjusting for potential confounders, treatment with dexamethasone for longer than 14 days was associated with worse neurodevelopmental outcomes, with mean scores in BSID-III 7.4 (95% CI, -12.3 to -2.5) points lower in the motor domain (P = .003) and 5.8 (95% CI, -10.9 to -0.6) points lower in the language domain (P = .03), compared with unexposed infants.

CONCLUSIONS AND RELEVANCE

These findings suggest that long duration and higher cumulative dose of dexamethasone were associated with worse neurodevelopmental scores at corrected age 2 years. Potential unmeasured differences in the clinical conditions of exposed vs unexposed infants may contribute to these findings. Improved standardization of treatment and documentation of indications would facilitate replication studies.

Effect of cumulative dexamethasone dose in preterm infants on neurodevelopmental and growth outcomes: a Western Australia experience

OBJECTIVE

Comparing the long-term neurodevelopmental and growth outcomes of lower and higher cumulative dexamethasone exposure in preterm infants ventilated for a minimum cumulative duration of 7 days.

DESIGN

A retrospective cohort medical chart review of infants born in Western Australia <29 weeks' gestation between January 2007 and May 2016 who were mechanically ventilated >7 days.

INTERVENTION

No dexamethasone (controls) or a total cumulative dexamethasone dose of <2 mg/kg (lower) and ≥2 mg/kg (higher).

MAIN OUTCOME MEASURES

Long-term disability at 2 and 5 years and growth measurement outcomes at 2 years of age.

RESULTS

Dexamethasone was given to 104 infants (66 with cumulative dose <2 mg/kg; 38 with cumulative dose ≥2 mg/kg), and 324 infants were controls. There was no difference in odds of long-term disability in infants with any dexamethasone exposure compared with controls (aOR: 0.90, 95% CI 0.34 to 2.02, p=0.784). No difference in long-term disability was found between the lower and higher groups (p=0.494). The prevalence of cerebral palsy (Gross Motor Functional Classification System level ≥2) between the control, lower and high-dose groups did not differ significantly (5.8% vs 4.0% vs 0%). The higher dose group had lower mean weight z-score (mean effect: -0.83, 95% CI: -1.54 to -0.01, p=0.023), height z-score (mean effect: -0.63, 95% CI: -12.5 to -0.01, p=0.048) and head circumference z-score (mean effect: -0.65, 95% CI: -1.25 to -0.05, p=0.035) compared with controls.

CONCLUSIONS

In our cohort, dexamethasone use was not associated with increased odds of long-term disability. Dexamethasone use was associated with lower growth measurements compared with controls.

Bone Mineral Density in Adolescent Boys: Cross-Sectional Observational Study

Physical inactivity of children can be a precursor of reduced bone mineral density, considered to be a typical problem only in old age. The aim of this study was to evaluate bone mineral density in 96 Polish boys aged 14–17 years with varied physical activity (swimmers, track and field athletes, non-athletes) and the effect of bone composition, birth weight and breastfeeding during infancy on bone parameters. Anthropometric and body composition measurements were performed according to the kinanthropometric standards. Bone parameters of the forearm were measured by means of dual-energy X-ray absorptiometry. Data on the infant’s birth weight and the length of breastfeeding were collected during direct interviews with mothers. The strongest links with bone parameters were found for the type of physical activity and birth weight. Regardless of birth weight, track and field athletes had the most advantageous bone parameters (mainly sT-score prox values). Swimmers with normal or low birth weight had less favourable sT-score prox values than non-athletes. The type of physical activity proved to be an important determinant of bone parameters. Childhood and adolescence are important periods of bone development and increasing the content of bone mineral components, and the bone status in later years of life depends to a large extent on this period. The perinatal period, especially the correct birth weight of the child, not only has a significant effect on general health, but also on bone status.

Lung abnormalities do not influence aerobic capacity in school children born preterm

PURPOSE

Children born preterm have impaired lung function and altered lung structure. However, there are conflicting reports on how preterm birth impacts aerobic exercise capacity in childhood. We aimed to investigate how neonatal history and a diagnosis of bronchopulmonary dysplasia (BPD) impact the relationship between function and structure of the lung, and aerobic capacity in school-aged children born very preterm.

METHODS

Preterm children (≤ 32 w completed gestation) aged 9-12 years with (n = 38) and without (n = 35) BPD, and term-born controls (n = 31), underwent spirometry, lung volume measurements, gas transfer capacity, a high-resolution computer tomography (CT) scan of the chest, and an incremental treadmill exercise test.

RESULTS

Children born preterm with BPD had an elevated breathing frequency to tidal volume ratio compared to term controls (76% vs 63%, p = 0.002). The majority (88%) of preterm children had structural changes on CT scan. There were no differences in peak V̇O₂ (47.1 vs 47.7 mL/kg/min, p = 0.407) or oxygen uptake efficiency slope when corrected for body weight (67.6 vs 67.3, p = 0.5) between preterm children with BPD and term controls. There were no differences in any other exercise outcomes. The severity of structural lung disease was not associated with exercise outcomes in this preterm population.

CONCLUSION

Children born preterm have impaired lung function, and a high prevalence of structural lung abnormalities. However, abnormal lung function and structure do not appear to impact on the aerobic exercise capacity of preterm children at school age.

Successful use of an artificial placenta-based life support system to treat extremely preterm ovine fetuses compromised by intrauterine inflammation

BACKGROUND

Ex vivo uterine environment therapy is an experimental intensive care strategy for extremely preterm infants born between 21 and 24 weeks of gestation. Gas exchange is performed by membranous oxygenators connected by catheters to the umbilical vessels. The fetus is submerged in a bath of synthetic amniotic fluid. The lungs remain fluid filled, and pulmonary respiration does not occur. Intrauterine inflammation is strongly associated with extremely preterm birth and fetal injury. At present, there are no data that we are aware of to show that artificial placenta-based systems can be used to support extremely preterm fetuses compromised by exposure to intrauterine inflammation.

OBJECTIVE

To evaluate the ability of our ex vivo uterine environment therapy platform to support extremely preterm ovine fetuses (95-day gestational age; approximately equivalent to 24 weeks of human gestation) exposed to intrauterine inflammation for a period of 120 hours, the following primary endpoints were chosen: (1) maintenance of key physiological variables within normal ranges, (2) absence of infection and inflammation, (3) absence of brain injury, and (4) gross fetal growth and cardiovascular function matching that of age-matched in utero controls.

STUDY DESIGN

Ten ewes with singleton pregnancies were each given a single intraamniotic injection of 10-mg Escherichia coli lipopolysaccharides under ultrasound guidance 48 hours before undergoing surgical delivery for adaptation to ex vivo uterine environment therapy at 95-day gestation (term=150 days). Fetuses were adapted to ex vivo uterine environment therapy and maintained for 120 hours with constant monitoring of key vital parameters (ex vivo uterine environment group) before being killed at 100-day equivalent gestational age. Umbilical artery blood samples were regularly collected to assess blood gas data, differential counts, biochemical parameters, inflammatory markers, and microbial load to exclude infection. Ultrasound was conducted at 48 hours after intraamniotic lipopolysaccharides (before surgery) to confirm fetal viability and at the conclusion of the experiments (before euthanasia) to evaluate cardiac function. Brain injury was evaluated by gross anatomic and histopathologic investigations. Eight singleton pregnant control animals were similarly exposed to intraamniotic lipopolysaccharides at 93-day gestation and were killed at 100-day gestation to allow comparative postmortem analyses (control group). Biobanked samples from age-matched saline-treated animals served as an additional comparison group. Successful instillation of lipopolysaccharides into the amniotic fluid exposure was confirmed by amniotic fluid analysis at the time of administration and by analyzing cytokine levels in fetal plasma and amniotic fluid. Data were tested for mean differences using analysis of variance.

RESULTS

Six of 8 lipopolysaccharide control group (75%) and 8 of 10 ex vivo uterine environment group fetuses (80%) successfully completed their protocols. Six of 8 ex vivo uterine environment group fetuses required dexamethasone phosphate treatment to manage profound refractory hypotension. Weight and crown-rump length were reduced in ex vivo uterine environment group fetuses at euthanasia than those in lipopolysaccharide control group fetuses (P<.05). There were no biologically significant differences in cardiac ultrasound measurement, differential leukocyte counts (P>.05), plasma tumor necrosis factor α, monocyte chemoattractant protein-1 concentrations (P>.05), or liver function tests between groups. Daily blood cultures were negative for aerobic and anaerobic growth in all ex vivo uterine environment group animals. No cases of intraventricular hemorrhage were observed. White matter injury was identified in 3 of 6 lipopolysaccharide control group fetuses and 3 of 8 vivo uterine environment group fetuses.

CONCLUSION

We report the use of an artificial placenta-based system to support extremely preterm lambs compromised by exposure to intrauterine inflammation. Our data highlight key challenges (refractory hypotension, growth restriction, and white matter injury) to be overcome in the development and use of artificial placenta technology for extremely preterm infants. As such challenges seem largely absent from studies based on healthy pregnancies, additional experiments of this nature using clinically relevant model systems are essential for further development of this technology and its eventual clinical application.

Do preterm bones still break? Incidence of rib fracture and osteopenia of prematurity in very low birth weight infants

AIM

Extremely premature babies are at risk of osteopenia of prematurity (OOP) as bone mineralisation in utero increases exponentially after 24 weeks gestation. Our aim was to assess the bone health of very low birth weight (VLBW) infants. We wanted to establish the incidences of OOP and rib fracture. We also looked at which biochemical markers best predicted OOP. Bone health in this vulnerable population is an important aspect of management which should not be overlooked.

METHODS

This was an observational study which included all VLBW infants, born in a national maternity hospital, over a 5-year period. All X-rays performed on these infants were reviewed. Data were also collected on biochemical markers associated with bone health. The medical records of infants with rib fractures were reviewed looking for causes of bone fragility.

RESULTS

Of the 609 VLBW infants included in the study, only two cases of definitive rib fractures were found. This represents a rib fracture incidence of 3 per 1000. Thirty-nine percent of VLBW babies showed radiological evidence suggestive of OOP.

CONCLUSION

Our findings show a lower rate of rib fracture in preterm infants compared to previous evidence. We also showed that these fractures were not evident on the final X-ray prior to discharge. This implies that when an ex-preterm infant presents to the emergency department with a rib fracture there should be an even higher suspicion for non-accidental injury than previously thought.

Extended course of prednisolone in infants with severe bronchopulmonary dysplasia

BACKGROUND

There are few published data on the efficacy and safety of prednisolone in preterm infants with bronchopulmonary dysplasia (BPD).

AIMS

To describe the use of chronic prednisolone therapy in a population of infants with severe BPD, examine potential benefits on respiratory status, and document potential effects on growth.

STUDY DESIGN

Single-center retrospective cohort study.

SUBJECTS

Preterm infants who had received ≥30 days of prednisolone for the treatment of severe BPD.

OUTCOME MEASURES

Weekly changes in Pulmonary Severity Score (PSS), as well as weekly changes in weight, length, and head circumference during prednisolone therapy.

RESULTS

Forty-three infants (mean birth weight 729 g; mean gestational age 26 weeks) were identified. The average age at start of prednisolone treatment was 42.5 ± 5.9 weeks; while the median duration and median cumulative dose of prednisolone therapy were 67 (IQR 57-107) days and 61.3 (IQR 39.9-93.3) mg/kg, respectively. PSS decreased after 1 week of prednisolone therapy (mean difference, 0.19; 95% Cl, 0.01 to 0.37; p = 0.03). No further reduction in PSS was noted despite continued treatment. Length z-scores decreased after 4 weeks of continued treatment (mean difference 0.6; 95% CI 0.01 to 1.1; P = 0.04), while weight and head circumference did not change.

CONCLUSIONS

In one of the first reports on prednisolone therapy for severe BPD, we describe that long-term prednisolone is associated with modest short-term improvement in PSS, but impairs linear growth. Our results suggest a risk-benefit profile of prednisolone that does not favor long-term use in infants with severe BPD.

Metabolic bone disease of prematurity: causes, recognition, prevention, treatment and long-term consequences

Metabolic bone disease of prematurity (MBDP) is characterised by skeletal demineralisation, and in severe cases it can result in fragility fractures of long bones and ribs during routine handling. MBDP arises from prenatal and postnatal factors. Infants who are born preterm are deprived of fetal mineral accumulation, 80% of which occurs in the third trimester. Postnatally, it is difficult to maintain a comparable intake of minerals, and medications, such as corticosteroids and diuretic therapy, lead to bone resorption. With improvements in neonatal care and nutrition, the incidence of MBDP in preterm infants appears to have decreased, although the recent practice of administering phosphate supplements alone will result in secondary hyperparathyroidism and associated bone loss, worsening MBDP. Postnatal immobilisation and loss of placental supply of oestrogen also contribute to skeletal demineralisation. There is no single diagnostic or screening test for MBDP, with pitfalls existing for most radiological and biochemical investigations. By reviewing the pathophysiology of calcium and phosphate homeostasis, one can establish that plasma parathyroid hormone is important in determining the aetiology of MBDP - primarily calcipaenia or phosphopaenia. This will then direct treatment with the appropriate supplements while considering optimal physiological calcium to phosphate ratios.

Effect of foetal and infant growth and body composition on respiratory outcomes in preterm-born children

Body composition and growth outcomes of preterm-born subjects have been studied by many researchers. In general, preterm-born children have lower height and weight especially in infancy. Despite showing potential for catch-up growth, they continue to lag behind their term counterparts in adolescence and adulthood. The various methods of studying body composition and the differing gestations and ages at which it is assessed may go some way to explaining the inconsistent results observed in different studies. In addition, there is a paucity of data on the effects of foetal and infant growth and of body composition on later respiratory outcomes. In largely term-born subjects, foetal growth and growth trajectories appear to have differential effects on later respiratory outcomes. Early weight gain in infancy appears to be associated with increased respiratory symptoms in childhood but catch-up growth in infancy appears to be associated with possible improved lung function status.

Can Basic Characteristics Estimate Body Composition in Early Infancy?

OBJECTIVES

Increasing evidence demonstrates that body composition in early life contributes to the programming of health later in life in both full-term and preterm infants. Given the important role of body composition, the increased availability of easy, noninvasive, and accurate techniques for its assessment has been recommended. The aim of the present study was to identify basic characteristics and anthropometric measurements that best correlate with body composition in infants.

METHODS

Anthropometric measurements and body composition assessed by air-displacement plethysmography were assessed either at birth or at term-corrected age in 1239 infants (654 full-term, 585 preterm). The associations of sex, GA (gestational age), and weight with FFM (fat-free mass) and FM (fat mass) adjusted by length (g/cm) were investigated by multiple linear regression models. Bland-Altman tests were performed, and an equation for calculating FFM was determined.

RESULTS

Preterm infants exhibited increased FM and reduced FFM compared with full-term infants (477.6 ± 204 vs 259.7 ± 147 g and 2583 ± 494 vs 2770 ± 364 g, respectively). GA, male sex, and weight were positively associated with FFM (r = 0.806, P < 0.0001; 6.1 g of average bias). GA and male sex were negatively associated with FM, whereas weight was positively associated with FM (r = 0.641, P < 0.0001; 4.9 g of average bias).

CONCLUSIONS

The assessment of body composition represents the criterion standard. When body composition assessment is not feasible, the equation based on sex, GA, and anthropometric measurements can be useful in predicting body composition in both full-term and preterm infants.

Neonatal corticosteroid therapy affects growth patterns in early infancy

Objective

Although postnatal corticosteroid (CS) therapy has well established beneficial effects on pulmonary function, it may also result in growth restriction during treatment. The course of early childhood growth is believed to predict cardiovascular and metabolic diseases in adulthood. Therefore, we determined the effects of postnatal dexamethasone (DEX) or hydrocortisone (HC) treatment on patterns of postnatal growth until approximately four years of age.

Study design

In an observational cohort study of children born prematurely (<32 weeks of gestation), we compared growth patterns for body weight, height, and head circumference from birth to age four years, of children who received DEX (boys: N = 30, girls: N = 14), HC (boys: N = 33, girls: N = 28) to a reference group that had not received postnatal CSs (boys: N = 52, girls: N = 53) using linear mixed-effects modeling.

Results

Growth velocity curves of CS-treated neonates showed a shift to the right, representing a delay in time. They had decreased absolute growth velocities during and shortly after treatment, followed by an increase in growth velocity thereafter. A shift to the right was also seen for the age at which maximal growth velocity of weight/height was reached in boys and girls. Fractional growth rates of weight, height, and head circumference were generally reduced in the CS-treated groups during the first two months of age, with catch-up growth in the following months. In DEX-treated infants these changes were more pronounced than in HC-treated infants.

Conclusion

These data suggest that postnatal growth patterns of preterm born infants are affected by CS-treatment, more by DEX than by HC. Effects were observed mainly on growth velocities. This observation may have impact on health in later life for those individuals treated with CSs in the neonatal period. A definitive conclusion would require a randomized trial of these therapies.

Perinatal Risk Factors and Genu Valgum Conducive to the Onset of Growing Pains in Early Childhood

The most prevalent musculoskeletal disorder of childhood with unclear aetiology is growing pains (GPs). Anatomic deformities and factors that change bone turnover are implicated in GP pathophysiology. Perinatal risk factors alter the bone metabolism affecting the bone mineral density and content. The aim of our study was to analyze the relationship between GPs, knock knees and perinatal factors. The examined population consisted of 276 children aged 3–7 years. Among them, ten pairs of dizygotic twins were evaluated. The data were collected by using a combination of semi-structured questionnaires, clinical examinations and medical charts of the children and the obstetric history of the mothers. A total of 78 children presenting GPs met Peterson’s criteria. Genu valgum severity was a significant factor for GP manifestation and for their increased frequency and intensity. Subsequently, perinatal factors regarding gestational age, Apgar score, head circumference (lower than 33 cm) and birth length or weight (smaller than 50 cm and 3000 g, respectively) made a remarkable contribution to the development of GPs. Conversely, antenatal corticosteroid treatment, increased maternal age and maternal smoking during pregnancy were not predictive of the disorder. Our data are potentially supportive for the “bone strength” theory and for the contribution of anatomical disturbances in GP appearance.

Early development and osteoporosis and bone health

Osteoporosis is a skeletal disorder characterized by low bone mass and micro-architectural deterioration of bone tissue with a consequent increase in bone fragility and susceptibility to fracture. Evidence is now accumulating from human studies that programming of bone growth might be an important contributor to the later risk of osteoporotic fracture. Body weight in infancy is a determinant of adult bone mineral content, as well as of the basal levels of activity of the growth hormone/insulin-like growth factor-1 (GH/IGF-1) and hypothalamo-pituitary-adrenal (HPA) axes, and recent work has suggested a central role for vitamin D. Epidemiological studies have shown that maternal smoking and nutrition during pregnancy influence intrauterine skeletal mineralization. Childhood growth rates have been directly linked to the risk of hip fracture many decades later, and now evidence is emerging from experimental animal studies that support these observational data. Recent studies have also highlighted epigenetic phenomena as potential mechanisms underlying the findings from epidemiological studies.

Calcium and vitamin d requirements of enterally fed preterm infants

Bone health is a critical concern in managing preterm infants. Key nutrients of importance are calcium, vitamin D, and phosphorus. Although human milk is critical for the health of preterm infants, it is low in these nutrients relative to the needs of the infants during growth. Strategies should be in place to fortify human milk for preterm infants with birth weight <1800 to 2000 g and to ensure adequate mineral intake during hospitalization and after hospital discharge. Biochemical monitoring of very low birth weight infants should be performed during their hospitalization. Vitamin D should be provided at 200 to 400 IU/day both during hospitalization and after discharge from the hospital. Infants with radiologic evidence of rickets should have efforts made to maximize calcium and phosphorus intake by using available commercial products and, if needed, direct supplementation with these minerals.

Preterm birth and the metabolic syndrome in adult life: a systematic review and meta-analysis

BACKGROUND

Preterm birth is associated with features of the metabolic syndrome in later life. We performed a systematic review and meta-analysis of studies reporting markers of the metabolic syndrome in adults born preterm.

METHODS

Reports of metabolic syndrome-associated features in adults (≥18 years of age) born at <37-week gestational age and at term (37- to 42-week gestational age) were included. Outcomes assessed were BMI, waist-hip ratio, percentage fat mass, systolic (SBP) and diastolic (DBP) blood pressure, 24-hour ambulatory SBP and DBP, flow-mediated dilatation, intima-media thickness, and fasting glucose, insulin, and lipid profiles.

RESULTS

Twenty-seven studies, comprising a combined total of 17,030 preterm and 295,261 term-born adults, were included. In adults, preterm birth was associated with significantly higher SBP (mean difference, 4.2 mm Hg; 95% confidence interval [CI], 2.8 to 5.7; P < .001), DBP (mean difference, 2.6 mm Hg; 95% CI, 1.2 to 4.0; P < .001), 24-hour ambulatory SBP (mean difference, 3.1 mm Hg; 95% CI, 0.3 to 6.0; P = .03), and low-density lipoprotein (mean difference, 0.14 mmol/L; 95% CI, 0.05 to 0.21; P = .01). The preterm-term differences for women was greater than the preterm-term difference in men by 2.9 mm Hg for SBP (95% CI [1.1 to 4.6], P = .004) and 1.6 mm Hg for DBP (95% CI [0.3 to 2.9], P = .02).

CONCLUSIONS

For the majority of outcome measures associated with the metabolic syndrome, we found no difference between preterm and term-born adults. Increased plasma low-density lipoprotein in young adults born preterm may represent a greater risk for atherosclerosis and cardiovascular disease in later life. Preterm birth is associated with higher blood pressure in adult life, with women appearing to be at greater risk than men.

The relationship of poor linear growth velocity with neonatal illness and two-year neurodevelopment in preterm infants

BACKGROUND

Poor postnatal weight gain in very low birth weight (VLBW) preterm infants has been shown to have a negative effect on neurodevelopment. However, the dose-dependent neurodevelopmental consequences of linear stunting in this population have not previously been assessed. Understanding this relationship is important because organ growth and differentiation are more tightly linked to lean body mass and thus linear growth.

OBJECTIVE

To assess the duration and clinical determinants of poor linear growth and its relationship to neurodevelopment in preterm infants.

METHODS

Weight, recumbent length and head circumference were recorded at birth, hospital discharge, and at 4, 12 and 24 months corrected age (CA) in 62 VLBW infants. Standardized Z-scores for weight (WZ), length (LZ) and head circumference (HCZ) were calculated and assessed as a function of inpatient clinical factors using linear regression models. Twenty-four-month neurodevelopmental function was analyzed as a function of growth status.

RESULTS

Mean LZ was lower than WZ (p = 0.004) at hospital discharge, was related in part to illness severity and remained lower than baseline LZ until 24 months CA. Controlling for WZ and HCZ at each age, lower LZ at 4 and 12 months CA was associated with lower cognitive function scores at 24 months CA (p ≤ 0.03).

CONCLUSIONS

Nutritional and non-nutritional factors influenced the degree of pre- and postdischarge linear growth suppression in VLBW infants, which in turn was negatively associated with developmental outcomes at 24 months CA. Since linear growth correlates with brain growth and indexes a number of clinical factors, it is an important biomarker that can be used in VLBW infants to predict long-term developmental outcomes.

Preterm birth and the endocrine regulation of growth in childhood and adolescence

OBJECTIVE

Poor growth during childhood is a common problem associated with preterm birth, but few studies have examined the associations between linear growth, weight and body composition with the postnatal hormonal milieu in preterm children. We aimed to define the IGF-IGFBP axis in preterm children and its association with growth.

DESIGN AND PATIENTS

A cohort of healthy 2- to 20-year-old subjects who were born prematurely (<37 weeks gestation) and experienced normal neurological development were recruited. In total, 54 premature and 82 control subjects were included in this study.

RESULTS

Preterm subjects were relatively shorter (P < 0·001) and leaner (P < 0·05) than their parents in contrast to the term cohort. Preterm children also appeared to fail to reach their genetic height potential (prepuberty: P < 0·01; puberty: P < 0·05). Only IGFBP-2 differed between preterm and term cohorts, with higher levels observed in prepubertal preterm subjects (P < 0·01). In the term group, height SDS was positively associated with IGF-I (P < 0·01) and IGFBP-3 (P < 0·001) concentrations, but no such associations were observed for preterm subjects.

CONCLUSION

Preterm children are shorter and lighter than controls throughout childhood, remaining below their genetic height potential. Preterm birth appears to alter the endocrine regulation of postnatal growth in childhood and adolescence, so growth is no longer associated with its normal endocrine regulators.

Decreased bone mineral density in adults born with very low birth weight: a cohort study

BACKGROUND

Very-low-birth-weight (VLBW, <1,500 g) infants have compromised bone mass accrual during childhood, but it is unclear whether this results in subnormal peak bone mass and increased risk of impaired skeletal health in adulthood. We hypothesized that VLBW is associated with reduced bone mineral density (BMD) in adulthood.

METHODS AND FINDINGS

The Helsinki Study of Very Low Birth Weight Adults is a multidisciplinary cohort study representative of all VLBW births within the larger Helsinki area from 1978 to 1985. This study evaluated skeletal health in 144 such participants (all born preterm, mean gestational age 29.3 wk, birth weight 1,127 g, birth weight Z score 1.3), and in 139 comparison participants born at term, matched for sex, age, and birth hospital. BMD was measured by dual energy X-ray absorptiometry at age 18.5 to 27.1 y. Adults born with VLBW had, in comparison to participants born at term, a 0.51-unit (95% confidence interval [CI] 0.28-0.75) lower lumbar spine Z score and a 0.56-unit (95% CI 0.34-0.78) lower femoral neck Z score for areal BMD. These differences remained statistically significant after adjustment for the VLBW adults' shorter height and lower self-reported exercise intensity.

CONCLUSIONS

Young adults born with VLBW, when studied close to the age of peak bone mass, have significantly lower BMD than do their term-born peers. This suggests that compromised childhood bone mass accrual in preterm VLBW children translates into increased risk for osteoporosis in adulthood, warranting vigilance in osteoporosis prevention.

Prenatal diagnosis and treatment of steroid 21-hydroxylase deficiency

Steroid 21-hydroxylase deficiency (21-OHD) accounts for 90–95% of congenital adrenal hyperplasia (CAH) cases. It is classified into three distinct clinical phenotypes: the salt-wasting (SW), simple virilizing (SV) and nonclassical forms (NC). As girls with the SW and SV forms of 21-OHD are exposed to high systemic levels of adrenal androgens during fetal life, they show genital ambiguity. To ameliorate the degree of genital virilization, prenatal dexamethasone treatment has been performed for more than two decades, although mainly in the USA and Europe. This treatment has proven to be effective in preventing or reducing genital virilization. Some data also show that prenatal diagnosis and treatment are safe for the mother and fetus. However, prenatal treatment is still controversial for the following reasons. First, the risk of having an affected female fetus is only one in eight when both parents are known carriers of the autosomal recessive trait. Therefore, seven of eight fetuses will receive dexamethasone unnecessarily, and this raises ethical questions. Furthermore, maternal side effects such as excessive weight gain and hypertension have been observed. Finally, the long-term safety and outcome for dexamethasone-exposed children have not been established. In Japan, prenatal diagnosis and treatment has rarely been reported because of these reasons. Therefore, we must be cautious, and this treatment should be carried out in special centers with the approval of their ethical committees, that are capable of performing chorionic villus sampling (CVS) and subsequently determining the karyotype and genotype of 21-OHD.

Outcome of very low birthweight infants after introducing a new standard regime with the early use of nasal CPAP

In this paper, a retrospective study was performed to find out whether the introduction of early nasal continuous positive airway pressure (nCPAP) as a new standard regime of very low birthweight infants will lead to a decreasing tracheal intubation and ventilation rate, as well as to a lower incidence of bronchopulmonary dysplasia in a tertiary-level perinatal centre. Ninety-three infants (study group) with early nCPAP as the first respiratory support were compared to 63 infants (historical control group) born before the use of early nCPAP. No statistically significant differences were found in the baseline characteristics. The main results of the study include reduced intubation mainly in infants with a birthweight <1,000 g (study group): 58% vs. 81% (p < 0.05). The mean duration of ventilation was 248 h (control group) vs. 128 h (study group) (p < 0.001) and 437 h vs. 198 h in infants <1,000 g (p < 0.001). There was significantly reduced incidence of bronchopulmonary dysplasia from 55% to 18% for all surviving infants (p < 0.001), and for infants <1,000 g, it was 90% vs. 30% (p < 0.001). No significant differences for other outcome criteria were noted, but a significant reduction in the use of central i.v. lines, fluids, drugs, volume expansion, sedation, catecholamines, surfactant, steroids and buffer, as well as antibiotics, was observed (p < 0.05). Therefore, we can conclude that early nCPAP is an easy-to-use and safe procedure for very low birthweight infants to treat respiratory distress.