Increments in whole body bone mineral content associated with weight and length in pre-term and full-term infants during the first 6 months of life

Untangle the relationship of muscle mass and bone mineral content on handgrip strength: Results of ELSA-Brasil

The study aims to investigate the independent association of muscle mass (MM) and bone mineral content (BMC) in the performance of the handgrip strength (HGS) test and whether there is effect modification by sex and age. In 12,491 participants from the ELSA-Brasil we estimated the associations between MM, BMC and HGS using linear regression models. All the analyses were performed for total population, also stratified for sex and age. For total population an interaction term was included between each explanatory variable of interest with sex and age to verify the presence of effect modification. We observed that the higher quintiles of MM and BMC were associated to an increasing in the mean of HGS compared to the first quintile, with greater magnitudes in men compared to women, also adults compared to elderly. When we estimated the independent effect of each exposure of interest, MM showed stronger effect in HGS in women, men and adults then BMC. In conclusion, we observed that higher amounts of MM and BMC are associated with higher HGS, regardless of sociodemographic characteristics, health conditions and lifestyle, with this effect being greater in men and adults.

Sodium Glycerophosphate Use in Parenteral Nutrition Improves Mineral Metabolism in Extremely Low Birth Weight Infants

OBJECTIVE

To evaluate the clinical effect of sodium glycerophosphate (NaGP) in parenteral nutrition solutions on mineral metabolism in extremely low birth weight (ELBW) infants.

STUDY DESIGN

NaGP was introduced for use in place of potassium phosphate (K₃PO₄) in January 2018; this retrospective cohort study included 95 ELBW infants treated with K₃PO₄ between January 2015 and December 2017 and 77 infants treated with NaGP between August 2018 and January 2021. Mineral intake over the first 14 days; changes in serum calcium, phosphorus, sodium, and alkaline phosphatase (ALP) levels over the first 1-3 months; and the rates of electrolyte imbalance and clinical morbidity were compared. High-risk infants who had nil per os (NPO) status for >14 days and prolonged parenteral nutrition exposure were further analyzed as a subgroup.

RESULTS

The use of NaGP instead of K₃PO₄ significantly increased Ca and P intake, but intakes remained below the recommended range (Ca, 64-140 mg/kg/day; P, 50-108 mg/kg/day). Compared with levels in the K₃PO₄ group, the NaGP group had significantly higher serum Ca and P levels after day 14 and lower ALP levels after day 56. In the subgroup analysis, the NaGP group had significantly lower incidences of hypophosphatemia, hyponatremia, bronchopulmonary dysplasia, and ALP >500 IU/L.

CONCLUSIONS

Although the administration of NaGP instead of K₃PO₄ in parenteral nutrition regimens still did not provide adequate Ca and P intake for ELBW infants, higher intake significantly improved serum Ca and P levels, especially in ELBW infants with prolonged parenteral nutrition exposure.

Maternal Diet, Nutritional Status, and Birth-Related Factors Influencing Offspring's Bone Mineral Density: A Narrative Review of Observational, Cohort, and Randomized Controlled Trials

There is growing evidence that bone health may be programmed in the first years of life. Factors during the prenatal period, especially maternal nutrition, may have an influence on offspring’s skeletal development and thus the risk of osteoporosis in further life, which is an increasing societal, health and economic burden. However, it is still inconclusive which early life factors are the most important and to what extent they may affect bone health. We searched through three databases (PubMed, Google Scholar, Cochrane Library) and after eligibility criteria were met, the results of 49 articles were analyzed. This narrative review is an overall summary of up-to-date studies on maternal diet, nutritional status, and birth-related factors that may affect offspring bone development, particularly bone mineral density (BMD). Maternal vitamin D status and diet in pregnancy, anthropometry and birth weight seem to influence BMD, however other factors such as subsequent growth may mediate these associations. Due to the ambiguity of the results in the analyzed studies, future, well-designed studies are needed to address the limitations of the present study.

Ultrasonic Backscatter Difference Measurement of Bone Health in Preterm and Term Newborns

Metabolic bone disease of prematurity remains a significant problem for preterm infants. Quantitative ultrasound (QUS) has potential as a non-invasive tool for assessing bone health of newborns. The aim of this study was to assess bone health in preterm and term newborns using ultrasonic backscatter difference measurement. This study analyzed a total of 493 neonates, including 239 full-term infants (gestational age [GA] >37 wk), 201 preterm I infants (GA: 32-37 wk) and 53 extreme preterm II infants (GA <32 wk). Ultrasonic backscatter measurements were performed on the calcaneus of infants at birth, and the normalized mean of the backscatter difference spectrum (nMBD) was calculated as an ultrasonic index of neonatal bone status. Simple and multiple linear regressions were performed to determine the association of ultrasonic nMBD with GA, anthropometric characteristics and biochemical markers. Statistically significant differences in GA, anthropometric characteristics (birth weight, birth length [BL], birth head circumference and body mass index [BMI]) and biochemical markers (alkaline phosphatase, serum calcium and serum phosphate) were observed among preterm and term infants. The nMBD for term infants (median = 3.72 dB/μs, interquartile range [IR] = 1.95 dB/μs) was significantly higher than that for preterm I infants (median = 1.95 dB/μs, IR = 3.12 dB/μs), which was, in turn, significantly higher than that for preterm II infants (median = 0.19 dB/μs, IR = 3.50 dB/μs). The nMBD yielded moderate correlations (ρ = 0.57-0.62, p < 0.001) with GA and anthropometric characteristics and weak correlations (|ρ| = 0.08-0.21, p < 0.001 or not significant) with biochemical markers. Multivariate regressions revealed that only BL (p = 0.002) and BMI (p = 0.032) yielded significantly independent contributions to the nMBD measurement, and combinations of BL and BMI could explain up to 42% of the variation of nMBD in newborn infants. This study found that ultrasonic backscatter difference measurement might be helpful in bone health evaluation in preterm and term newborns. The utility of ultrasonic backscatter measurement in diagnosis of metabolic bone disease in infants should be investigated further.

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 early nutritional intake on long-term growth and bone mineralization of former very low birth weight infants

BACKGROUND

Preterm infants are at risk for impaired bone mineralization and growth in length later in life due to inadequate nutritional intake in the early postnatal period.

OBJECTIVE

To investigate whether increased nutritional supplementation of calcium, phosphate and protein in Very Low Birth Weight (VLBW) infants during the first 14days after birth was associated with improvement in length and bone development until 9-10years of age.

DESIGN

Observational follow-up study of VLBW infants (birth weight<1500g or gestational age<32weeks) born in two consecutive years (eligible infants: 2004 n: 63 and 2005: n: 66). Cohort 2005 received higher intake of calcium, phosphate and protein with parenteral nutrition compared to Cohort 2004. Anthropometric data were collected during standard follow-up visits until five years, and additionally at 9-10years of age including measurements of bone mineral content, bone mineral density of the whole body and lumbar spine determined by dual-energy X-ray absorptiometry. Long-term growth trajectories of both cohorts were evaluated separately for participants born appropriate (AGA) and small for gestational age (SGA), stratified by gender. Multivariate linear regression was used to examine the effect of nutritional intake and clinical covariates on length and bone mineralization.

RESULTS

Both cohorts achieved a catch-up in length to SDS within the normal range by 6months (length SDS: estimated mean (95% confidence interval (CI): 6months: Cohort 2004: -0.7 (-1.1, -0.3) Cohort 2005: -0.5 (-0.8, -0.2)). Bone mineral content and density were within the normal range and not different between the cohorts. SGA children achieved a catch-up in length at 5years with bone mineralization comparable to AGA children. Only for girls birth weight was significantly associated with length SDS (per gram: β 0.001; 95% CI (0.000, 0.003); p=0.03) There was no evidence of an association between early nutritional intake and bone mineralization.

CONCLUSION

Children born as appropriate or small for gestational age preterm infants are able to catch up in length after the postnatal period, and achieve a normal length and bone mineralization at age nine-ten years. An improvement of calcium and phosphate intake during the first 14days after birth was not associated with improvement in length and bone development.

Bone Mineral Density According to Dual Energy X-ray Absorptiometry is Associated with Serial Serum Alkaline Phosphatase Level in Extremely Low Birth Weight Infants at Discharge

BACKGROUND

To examine bone mineral density in extremely low birth weight infants at discharge and investigate whether serial measurements of serum alkaline phosphatase (ALP) and phosphate can predict bone mineralization.

METHODS

The individuals were 70 preterm infants. Serum calcium, phosphate, and ALP were measured at weekly intervals during admission in extremely low birth weight infants (mean gestational age, 25.3±2.1 weeks; birth weight, 812.8±141.1 g). Bone mineral apparent density (BMAD) of the lumbar spine was prospectively evaluated by dual energy X-ray absorptiometry at discharge (n=70).

RESULTS

BMAD was classified as poor (< 25^th percentile) at < 0.014 g/cm³, fair (25^th-75^th percentile) at < 0.014-0.021 g/cm³, and good (> 75^th percentile) at > 0.021 g/cm³, based on the distribution of BMAD values in infants with noncomplicated courses of prematurity (n=43). In a further multivariate analysis, the number of total parenteral nutrition days, phosphate at 2 postnatal weeks and 3 postnatal weeks, and ALP at 4 postnatal weeks and 5 postnatal weeks had an impact on bone mineral density at the lumbar spine, independent of gestational age and body weight. Peak ALP activities exceeding 650 IU/L revealed low bone mineral density with 80% sensitivity and 64% specificity (AUC, 0.70; p=0.005).

CONCLUSION

Serial measurements of serum ALP and phosphate are associated with decreased bone mineralization by dual energy X-ray absorptiometry at discharge in extremely low birth weight infants.

Time since onset of walking predicts tibial bone strength in early childhood

Bone strength in adulthood is known to be affected by health at birth and early childhood. Habitual bone loading is a primary determinant of bone strength in later childhood and adulthood. However, the effects of physical activity in early childhood (e.g. crawling, standing and walking) on bone strength are unknown. Fifty-three children (twenty-seven males) were included in a longitudinal study in their early infancy. Shortly after birth (0.3±0.3months), details of mass and height were obtained along with a pQCT scan at 20% distal-proximal tibia length. At 14.8±0.5months of age the same data were collected, along with details of age at onset of standing, crawling, supported and unsupported walking. Time since onset of walking unsupported was associated with greater bone mass, cortical bone area, pericortical circumference and polar moment of inertia of both total and cortical bone (all P<0.05). There were no significant associations between other physical activity timepoints and bone measures. Age at onset of walking was not significantly related to mass, length or bone measures at birth. The results suggest that time since attainment of independent walking - representing exposure of the tibia to the large reaction and muscular forces associated with locomotion - is a primary determinant of bone strength in early childhood. This finding raises the possible opportunity of physical activity interventions at young age in paediatric populations associated with low childhood bone strength and late walking (e.g. low birth weight, cerebral palsy and Down's Syndrome, etc.).

Bone densitometry by dual-energy X-ray absorptiometry (DXA) in preterm newborns compared with full-term peers in the first six months of life

OBJECTIVES

To longitudinally assess bone mineral content (BMC), bone mineral density (BMD), and whole-body lean mass obtained through bone densitometry by dual-energy X-ray absorptiometry (DXA) in preterm newborns (PTNs) and compare them with full-term newborns (FTNs) from birth to 6 months of corrected postnatal age.

METHODS

A total of 28 adequate for gestational age (AGA) newborns were studied: 14 preterm and 14 full-term newborns. DXA was used to determine BMC, BMD, and lean mass in three moments: 40 weeks corrected post-conceptual age, as well as 3 and 6 months of corrected postnatal age. PTNs had gestational age ≤ 32 weeks at birth and were fed their mother's own milk or milk from the human milk bank.

RESULTS

All infants had an increase in BMC, BMD, and lean body mass values during the study. PTNs had lower BMC, BMD, and lean mass at 40 weeks of corrected post-conceptual age in relation to FTNs (p<0.001, p<0.001, p=0.047, respectively). However, there was an acceleration in the mineralization process of PTNs, which was sufficient to achieve the normal values of FTNs at 6 months of corrected age.

CONCLUSIONS

This study suggests that bone densitometry by dual-energy X-ray absorptiometry is a good method for the assessment of body composition parameters at baseline, and at the follow-up of these PTNs.

Small-for-gestational-age preterm-born infants already have lower bone mass during early infancy

BACKGROUND

In preterm-born infants, low birth weight and diminished bone accretion deteriorate peak bone mass. Whether low birth weight is already associated with decreased bone mass during infancy is unknown.

OBJECTIVE

To study the effect of birth weight on bone accretion between term age (40 weeks postmenstrual age) and six months post-term in preterm-born infants.

DESIGN

In 139 preterm-born infants (51% male, gestational age 30.3±1.5 weeks, birth weight 1341±288g) weight and whole-body bone mineral content (BMC, gram) were measured at term age and six months post-term. At birth, infants were small-for-gestational-age (SGA, n=33, weight and/or length<-2 SDS) or appropriate-for-gestational-age (AGA, n=98, weight and length≥-2 SDS).

RESULTS

At term age and six months post-term, BMC adjusted for gender and gestational age was lower in SGA than AGA infants (term age: 38.1±9.5 versus 48.6±10.1g, β=-0.26, 95% CI -0.37; -0.16, p<0.001; six months: 130.1±25.7 versus 145.4±22.9g, β=-0.16, 95% CI -0.25; -0.08, p<0.001). At six months post-term, BMC remained lower in SGA infants after adjustment for actual weight and length. Between term age and six months post-term, BMC gain adjusted for gender and gestational age was lower in SGA than AGA infants (91.7±22.8 versus 98.2±20.7g; β=-0.12, 95% CI -0.24; -0.003, p=0.044). BMC gain remained lower in SGA infants after adjustment for weight and length gain.

CONCLUSION

The first six months post-term, SGA preterms have lower bone accretion, independent of body size, suggesting that prenatal conditions for bone accretion cannot be replicated postnatally.

Ultrasound for the assessment of bone quality in preterm and term infants

OBJECTIVE

As 80% of intrauterine bone mineralization takes place during the last trimester of pregnancy, preterm infants should be supplemented postnatally with optimal doses of calcium, phosphate and vitamin D. Calcium and phosphate excretion in the urine may be used to monitor individual mineral requirements, but are sometimes difficult to interpret. The objective of this study was to assess the value of quantitative ultrasound (QUS) for the analysis of bone status in neonates.

STUDY DESIGN

All admissions to three independent tertiary neonatal intensive care units were studied. In 172 preterm and term infants with a gestational age between 23 and 42 weeks (mean 33.8±5.0) and a birth weight from 405 to 5130 g (mean 2132±1091 g) bone status was evaluated prospectively by quantitative ultrasound velocity using a standardized protocol. Infants were followed in regular intervals up to their first discharge home. While measurements were conducted in weekly intervals initially (n=55), 2-week intervals were regarded as sufficient thereafter due to limited changes in QUS values within the shorter period. Infants with a birth weight below 1500 g were followed during outpatient visits until up to 17 months of age.

RESULT

The intra-individual day-to-day reproducibility was 0.62%. QUS-values from the first week of life correlated significantly with gestational age and birth weight (r=0.5 and r=0.6; P<0.001). Small-for-gestational-age infants showed lower values for QUS than appropriate-for-gestational-age infants allowing for their gestational age. Follow-up measurements correlated positively with age and weight during the week of measurement (r=0.2 and r=0.4; P=0.001). Comparing bone quality at 40 weeks of age in infants born at term versus infants born at 24 to 28 weeks, preterm infants showed significantly lower QUS than term infants (P<.0001).There was a significant correlation of QUS with serum alkaline phosphatase (P=0.003), the supplementation with calcium, phosphate and vitamin D (P< 0.001 each), as well as risk factors for a reduced bone mineralization. No correlation was found between QUS and calcium or phosphate concentration in serum or urine.

CONCLUSION

QUS is a highly reproducible, easily applicable and radiation-free technique that can be used to monitor bone quality in individual newborns. Further prospective randomized-trials are necessary to evaluate, if therapeutic interventions based on QUS are able to prevent osteopenia of prematurity.

Normative data for bone mass in healthy term infants from birth to 1 year of age

For over 2 decades, dual-energy X-ray absorptiometry (DXA) has been the gold standard for estimating bone mineral density (BMD) and facture risk in adults. More recently DXA has been used to evaluate BMD in pediatrics. However, BMD is usually assessed against reference data for which none currently exists in infancy. A prospective study was conducted to assess bone mass of term infants (37 to 42 weeks of gestation), weight appropriate for gestational age, and born to healthy mothers. The group consisted of 33 boys and 26 girls recruited from the Winnipeg Health Sciences Center (Manitoba, Canada). Whole body (WB) as well as regional sites of the lumbar spine (LS 1-4) and femur was measured using DXA (QDR 4500A, Hologic Inc.) providing bone mineral content (BMC) for all sites and BMD for spine. During the year, WB BMC increased by 200% (76.0 ± 14.2 versus 227.0 ± 29.7 g), spine BMC by 130% (2.35 ± 0.42 versus 5.37 ± 1.02 g), and femur BMC by 190% (2.94 ± 0.54 versus 8.50 ± 1.84 g). Spine BMD increased by 14% (0.266 ± 0.044 versus 0.304 ± 0.044 g/cm(2)) during the year. This data, representing the accretion of bone mass during the first year of life, is based on a representative sample of infants and will aid in the interpretation of diagnostic DXA scans by researchers and health professionals.

Association between calcium in cord blood and newborn size in Bangladesh

Ca status in the uterus during pregnancy has been suggested to affect fetal growth and size at birth. In Bangladesh, low Ca levels in pregnant women and low birth weight in infants are common. The present study explored the association between Ca levels in cord blood and newborn size at birth (birth weight and birth length) in Bangladesh. Samples and data included 223 women with live-born singleton deliveries in rural Bangladesh. Newborn weight and length were measured at birth. From cord blood obtained at delivery, Ca, 25-hydroxy vitamin D, bone-specific alkaline phosphatase and intact parathyroid hormone levels were determined. An association between size at birth and Ca levels in cord blood was found (birth weight, P = 0.022; birth length, P = 0.001). Associations between Ca and newborn size were further analysed using multivariate regression analyses. After adjusting for several covariates of characteristics in mothers and newborns (gestational weeks at birth, sex of newborn, socio-economic status, maternal height, BMI, age and season at birth), birth length still exhibited a significant relationship with Ca levels in cord blood (birth length, P = 0.030). The present study indicates that Ca status in cord blood might be associated with the birth length of newborns. Ca levels during gestation may affect fetal growth.

Fisioterapia motora no tratamento do prematuro com doença metabólica óssea

OBJETIVO: Revisar o papel da fisioterapia motora no prematuro com risco de desenvolver doença metabólica óssea. FONTES DE DADOS: Trata-se de uma revisão de literatura publicada entre 1986 e 2009, utilizando as seguintes palavras-chave: prematuro, calcificação fisiológica, modalidades de fisioterapia, doenças ósseas metabólicas e os respectivos descritores no idioma inglês. Foram selecionados 29 artigos científicos, via PubMed e ISI Web, além de um capítulo de livro nacional. SÍNTESE DOS DADOS: As doenças ósseas metabólicas compreendem um conjunto de condições relacionadas a alterações no processo de calcificação fisiológica, levando desde à fragilidade estrutural até ao desenvolvimento de fraturas. A aplicação rotineira de exercícios de mobilização passiva articular, massagem e posicionamento está relacionada ao ganho ponderal, ao aumento na densidade e no conteúdo mineral ósseo. CONCLUSÕES: A implementação de exercícios de fisioterapia motora parece proporcionar estabilidade ou estímulo para a formação óssea, podendo, consequentemente, prevenir e/ou minimizar as complicações decorrentes da doença metabólica óssea.

Quantitative ultrasound and biochemical parameters for the assessment of osteopenia in preterm infants

OBJECTIVE

Our study aimed to evaluate the feasibility of quantitative ultrasound (QUS) evaluation in osteopenia of prematurity and to compare the results to biochemical parameters.

METHODS

QUS assessment of bone was performed at the end of the first postnatal week and at term-corrected age (CA) in premature infants (N = 30) and within the first week in full-term infants (N = 25). On the same day of measurement of QUS, the serum calcium, phosphorus (inorganic), and alkaline phosphatase (ALP) activity were measured in the preterm infants.

RESULTS

The median of tibia z score at term-CA in premature infants was significantly lower compared to that of first postnatal week (-1 and 0.4, respectively; p < 0.0001) and it was also lower than that of term-matched controls (0.0; p = 0.001). Preterm infants at term-CA had lower weights and lengths in comparison to term infants. The median ALP value was 585 IU/L at the first postnatal week and 703 IU/L at term-CA in preterm infants (p = 0.003). The median tibia z score of infants with ALP >or=900 IU/L was significantly lower than that of the infants with ALP <900 IU/L (-1.4 vs. 0.1; p = 0.001). An inverse correlation was found between ALP levels and tibia z score at term-CA in preterm infants (rho = -0.61, p = 0.01).

CONCLUSIONS

Bone density of preterm infants at term-CA was lower than that at first postnatal week. Serum ALP levels increased during the first postnatal weeks. The tibia z scores were correlated to serum ALP levels. QUS is a good screening tool for the detection of osteopenia.

Vigorous physical activity increases fracture risk in children irrespective of bone mass: a prospective study of the independent risk factors for fractures in healthy children

Low bone mass is a determinant of fractures in healthy children. Small studies provide limited evidence on the association between ethnicity, birth weight, family size, socioeconomic status, dietary calcium intake, or physical activity and fracture incidence. No studies have investigated whether these determinants of fracture risk act through affecting bone mass or through other mechanisms. The aim of this study was to use a population-based birth cohort to confirm which variables are determinants of fracture risk and to further study which of these risk factors act independently of bone mass. Children from the Avon Longitudinal Study of Parents and Children have been followed up from birth to 11 yr of age. Maternal self-reported data have been collected contemporaneously on early life factors, diet, puberty, and physical activity. These were linked to reported fractures between 9 and 11 yr of age. Multivariable logistic regression techniques were used to assess whether these potential determinants were independent of, or worked through, estimated volumetric BMD or estimated bone size relative to body size measured by total body DXA scan at 9.9 yr of age. A total of 2692 children had full data. One hundred ninety-three (7.2%) reported at least one fracture over the 2-yr follow-up period. Children who reported daily or more episodes of vigorous physical activity had double the fracture risk compared with those children who reported less than four episodes per week (OR, 2.06; 95% CI, 1.21-1.76). No other independent determinants of fracture risk in healthy children were found. In conclusion, reported vigorous physical activity is an independent risk factor for childhood fracture risk. However, the interrelationship between physical activity, bone mass, and childhood fracture risk suggests that the higher bone mass associated with increased physical activity does not compensate for the risk caused by increased exposure to injuries.

Bone disease of prematurity

Bone disease of prematurity is a complication of preterm birth. This article reviews the aetiology, treatment and prevention of bone disease of prematurity. Provision of adequate nutrition including energy, protein, and minerals is required for both treatment and prevention. Screening for bone disease is controversial. While further research is required quantitative ultrasound appears to be a promising tool for screening and monitoring response to therapy. Further research is needed before recommending physical activity to prevent bone disease of prematurity.

Relationship of tibial speed of sound and lower limb length to nutrient intake in preterm infants

BACKGROUND

Metabolic bone disease of prematurity is characterised by impaired postnatal mineralisation of the rapidly growing infant skeleton.

OBJECTIVE

To longitudinally evaluate postnatal changes in tibial speed of sound (tSOS; which reflects cortical thickness and bone mineral density) and lower limb length (LLL; a measure of tibial growth) in very low birthweight preterm infants receiving contemporary neonatal care.

METHODS

tSOS and LLL were measured using a quantitative ultrasound device and an electronic neonatal knemometer, respectively, in the same limb, weekly, for a median period of four weeks (3-16 weeks) in 84 preterm infants (median gestation 26.8 weeks (range 23-35.2 weeks) and median birth weight 869.5 g (range 418-1481 g)).

RESULTS

Initial tSOS and LLL were correlated with gestation (r = 0.42, p<0.001; r = 0.76, p<0.001, respectively) and birth weight (r = 0.23, p = 0.038; r = 0.93, p<0.001, respectively). Postnatally, tSOS decreased (r = -0.15, p = 0.011) whereas LLL increased (r = 0.96, p<0.001) with age. The rate of postnatal change in LLL, but not in tSOS, was positively influenced by intake of calcium (p = 0.03), phosphorus (p = 0.01) and vitamin D (p = 0.03).

CONCLUSIONS

The postnatal decline in tSOS, which is probably due to cortical thinning secondary to endocortical bone loss, and increase in LLL provide new insight into the development of long bones in preterm infants.

Enteral calcium, phosphate and vitamin D requirements and bone mineralization in preterm infants

With major advances in life-support measures, nutrition has become one of the most debated issues in the care of very low birth-weight (VLBW) infants. Current nutritional recommendations are based on healthy premature infants and designed to provide postnatal nutrient retention during the 'stable-growing' period equivalent to the intrauterine gain of a normal foetus. However, this reference is still a matter of discussion, especially in the field of the mineral requirements. After birth, there are dramatic physiological changes in bone metabolism resulting from various factors: disruption in maternal mineral supply, stimulation of calciotropic hormone secretion, change in hormonal environment and relative reduction in mechanical stress. These events stimulate the remodelling process leading to an increase in endosteal bone resorption and a decrease in bone density. In preterm infants, these adaptation processes modify the mineral requirement, since, by itself, the increased remodelling provides a part of the mineral requirement necessary for postnatal bone growth and turnover. The care of newly born premature infants should not necessarily aim to achieve intrauterine calcium accretion rates.

CONCLUSION

Considering that a calcium retention level ranging from 60 to 90 mg/kg/day assures appropriate mineralization, and decreases the risk of fracture and diminishes the clinical symptoms of osteopenia, an intake of 100 to 160 mg/kg/day of highly bioavailable calcium salts, 60 to 90 mg/kg/day of phosphorus and 800 to 1000 IU of vitamin D per day is recommended.

Inadequate prenatal care and elevated blood lead levels among children born in Providence, Rhode Island: a population-based study

OBJECTIVE

This study was conducted to determine whether children born to mothers receiving inadequate prenatal care are at an increased risk for having an elevated blood lead level during early childhood.

METHODS

The authors conducted a population-based study of children born in Providence, Rhode Island, from 1997 to 2001 whose mothers had received adequate, intermediate, or inadequate prenatal care. The children's blood lead levels were compared between groups using bivariate and logistic regression. To understand the regulatory implications and public health impact of changing the definition of an elevated blood lead level, "elevated" was defined as 5 microg/dL, 10 microg/dL, and 15 microg/dL.

RESULTS

Children born to mothers who received inadequate prenatal care were at an elevated risk for having an elevated blood lead level later in life. This relationship remained statistically significant for each definition of elevated blood lead level and after controlling for other socio-economic status measures and birthweight (at 5 microg/dL, odds ratio [OR] = 1.36, 95% confidence interval [CI] 1.09, 1.68, p = 0.006; at 10 microg/dL, OR = 1.68, 95% CI 1.26, 2.24, p < 0.0004; at 15 microg/dL, OR = 1.83, 95% CI 1.10, 3.04, p = 0.019) represent an opportune moment to identify expectant mothers living in lead-contaminated environments.

CONCLUSIONS

Results suggest that conducting lead screening as a regular part of prenatal care provision could help identify women possibly experiencing ongoing lead exposure and help reduce or prevent exposures to their offspring.

Building Bones in Babies: Can and Should We Exceed the Human Milk-Fed Infant's Rate of Bone Calcium Accretion?

Increasing calcium absorption and bone calcium accretion to levels above those achieved by human milk-fed, full-term infants is possible with infant formulas. However, no data support such a goal or suggest that it is beneficial to short- or long-term bone health. Small differences in the bioavailability of calcium between infant formulas are unlikely to have long-term consequences. Long-term studies of the effects of infant feeding type on ultimate bone mass are needed. For now, the vitamin-replete breast-fed infant's rate of calcium accretion during the first year of life should be the standard targeted for infant formulas.

Phalangeal quantitative ultrasound measurements in former pre-term children aged 9-11 years

The objective of this study was to compare phalangeal ultrasound values in 38 former pre-term children, aged 9-11 years, with 50 age-matched term controls. Skeletal status was evaluated using phalangeal quantitative ultrasound measurements (QUS) by DBM Sonic 1200 (IGEA, Carpi, Italy) which measures the amplitude dependent speed of sound (Ad-SoS, m s(-1)). There were no significant differences in values of Ad-SoS, weight and height between patients and controls irrespective of birth weight or prematurity. In conclusion, phalangeal ultrasound measurements performed in prematurely born infants show that at the age of 9-11 years their bone status does not differ from children born at term.

Whole body bone mineral content is similar at discharge from the hospital in premature infants receiving fortified breast milk or preterm formula

BACKGROUND

Prematurely born infants, especially those with very low birth weight (<1500 g) are at risk for metabolic bone disease.

OBJECTIVES

The influence of the type of oral feeding regimen and of other potential determinants of whole bone mineral content in prematurely born infants, when they approached full gestation, were evaluated. Previous studies have mainly examined effects at the level of regional bone.

METHODS

34 infants (21 males and 13 females), all born between 25.4 and 33.7 weeks of gestation, were studied before discharge. Whole body bone mineral content measurements were made just before hospital discharge using a commercial densitometer (Hologic QDR 4500, Hologic Inc, Waltham, MA) at a median age of 40 days (range, 10 to 115 days) after birth.

RESULTS

Expressed as a percentage of whole body mass, bone mass ranged between 0.86% and 1.99%, was similar between girls and boys and correlated positively with birth weight SD (r=0.42; P<0.05) and body weight SD (r=0.35; P<0.05). No difference in bone mass percentage was found between the different types of oral feedings (fortified human milk and preterm formula) or medications studied (corticoids and diuretics).

CONCLUSIONS

Whereas prenatal and postnatal weight gain determines the degree of bone mineralization of premature infants, it appears that the type of oral feeding does not affect differently the postnatal bone mineralization of premature infants, when assessed at the moment of discharge.

In search of causative factors of deformational plagiocephaly

This is a preliminary study of 37 infants with deformational plagiocephaly. In this first effort to create a profile of factors that may contribute to the onset and progress of developmental plagiocephaly, parents were interviewed concerning selected practices before and immediately after the birth of their infants. Results of the study do not reveal a clear or concise pattern of factors that may contribute to this condition. There needs to be additional research on the benefits and potential hazards of sleep position to infants as one of the factors that may contribute to deformational plagiocephaly.

Lumbar bone mineral content and density measured using a Lunar DPX densitometer in healthy full-term infants during the first year of life

This cross-sectional study provides values for lumbar spine bone mineral content (BMC) and density (BMD) in 41 healthy full-term born Finnish infants, 19 boys and 22 girls, during the first year of life measured by dual energy X-ray absorptiometry (DXA) using the Lunar DPX densitometer. Lumbar BMC correlated with the weight (r=0.733; P=0.000), length (r=0.677; P=0.000), standardized length (r=0.315; r=0.045) and age at examination (r=0.314; P=0.045), and with the bone area (r=0.736; P=0.000). Infants with < or =-1 SD scores for lengths at examination had significantly lower BMC values [mean (SD); 1.79 (0.66) g] than infants with SD scores above -1 SD [2.27 (0.46) g] (P=0.011). Exclusive breast feeding did not correlate with the lumbar BMC values (r=-0.039; P=0.811). No differences were found in lumbar spine BMC (P=0.097), BMD (P=0.254) and bone area (P=0.094) values between boys and girls. In order to determine the predictive value of the anthropometric measurements on lumbar BMC, stepwise multiple regression analysis were performed, bone area and present weight were the only independent variables which explained 67.6% of the variance in the BMC values. The present cross-sectional data imply that, in healthy term infants, patterns of relative linear growth during the first year of life are related to the lumbar BMC values. In future, careful longitudinal measurements of linear growth are needed to study connections between growth patterns and bone mineral status in infancy.