Growth and bone mineralization in small-for-gestational-age preterm infants

Bone density and body composition in small for gestational age children with adequate catch up growth: A preliminary retrospective case control study

BACKGROUND

Fetal growth patterns and birth weight (BW) have been associated with bone mineral density (BMD) and content (BMC) throughout infancy and childhood up to early adulthood. We hypothesized that in small for gestational age (SGA) children, compensatory infant catch-up growth to normal height centiles counteracts the adverse consequences of low BW on bone accrual.

AIM

To evaluate BMD and BMC of SGA children born at term who experienced a normal catch-up growth as compared to children born appropriate for gestational age (AGA).

PATIENTS

We recruited 53 SGA (26 females) and 60 AGA children (27 females), aged 6 to 18 years, matched for sex and body mass index (BMI). Fat mass (FM); Free fat mass (FFM); Lumbar spine and Total body less head (TBLH) BMD; BMC and BMD standard deviation scores corrected for body size (BMAD, BMAD z-score and TBLH BMD/Height) and TBLH BMC for FFM (TBLHBMC/FFM) were derived from Dual Energy X-ray absorptiometry (DXA) scans.

RESULTS

SGA and AGA children did not differ in any auxological, body composition and bone parameters appropriately adjusted for height and FFM. BMI, FM and, remarkably, FFM were significantly correlated with bone mass parameters in both groups while no correlation was found between FM and FFM with the BW SDS in the univariate analysis.

CONCLUSION

Our preliminary data demonstrate that SGA children born at term who recover from their growth deficiency through catch-up growth achieve bone mass and body composition not different from children born AGA.

What is the evidence for beneficial effects of growth hormone treatment beyond height in short children born small for gestational age? A review of published literature

Background An increasing body of evidence supports the view that both an adverse intrauterine milieu and rapid postnatal weight gain in children born small for gestational age (SGA) contribute towards the risk for the development of chronic diseases in adult life. Content The aim of this review was to identify and summarize the published evidence on metabolic and cardiovascular risk, as well as risk of impaired cardiac function, intellectual capacity, quality of life, pubertal development and bone strength among children born SGA. The review will then address whether growth hormone (GH) therapy, commonly prescribed to reduce the height deficit in children born SGA who do not catch up in height, increases or decreases these risks over time. Summary Overall, there are limited data in support of a modest beneficial effect of GH therapy on the adverse metabolic and cardiovascular risk observed in short children born SGA. Evidence to support a positive effect of GH on bone strength and psychosocial outcomes is less convincing. Outlook Further evaluation into the clinical relevance of any potential long-term benefits of GH therapy on metabolic and cardiovascular endpoints is warranted.

Developmental Programming of Body Composition: Update on Evidence and Mechanisms

PURPOSE OF REVIEW

A growing body of epidemiological and experimental data indicate that nutritional or environmental stressors during early development can induce long-term adaptations that increase risk of obesity, diabetes, cardiovascular disease, and other chronic conditions-a phenomenon termed "developmental programming." A common phenotype in humans and animal models is altered body composition, with reduced muscle and bone mass, and increased fat mass. In this review, we summarize the recent literature linking prenatal factors to future body composition and explore contributing mechanisms.

RECENT FINDINGS

Many prenatal exposures, including intrauterine growth restriction, extremes of birth weight, maternal obesity, and maternal diabetes, are associated with increased fat mass, reduced muscle mass, and decreased bone density, with effects reported throughout infancy and childhood, and persisting into middle age. Mechanisms and mediators include maternal diet, breastmilk composition, metabolites, appetite regulation, genetic and epigenetic influences, stem cell commitment and function, and mitochondrial metabolism. Differences in body composition are a common phenotype following disruptions to the prenatal environment, and may contribute to developmental programming of obesity and diabetes risk.

Early application of the Ponseti casting technique for clubfoot correction in sick infants at the neonatal intensive care unit

The treatment of congenital clubfoot has been changing rapidly since the mid-1990s with the worldwide use of the Ponseti method for serial casting and limited operative interventions. This method was first applied for isolated clubfeet and later on for other types of clubfoot (teratologic, residual, and neurogenic). Premature babies sustaining clubfoot commonly suffer from additional congenital and acquired medical problems. These may postpone clubfoot management until urgent issues are resolved. The current study describes early initiation of treatment of clubfoot in premature babies at the neonatal intensive care unit (NICU) and their outcomes. The study group included all babies diagnosed with clubfoot and managed in the NICU (for any etiology) between 2006 and 2012. Management was based on the Ponseti protocol for serial casting. We also report on neonates who died in the NICU before or during treatment. We specifically describe adverse events of early casting and situations necessitating removal of casts or termination of treatment. We diagnosed and treated 20 neonates with clubfoot (four females and 16 males, 10 bilateral cases). Gestational age ranged from 27 weeks to term. Eight were identified with clubfoot by prenatal sonographic survey and 10 were diagnosed with a defined syndrome. Seven had respiratory support, including one with a chest drain (50%). Length of stay in the NICU ranged from 3 to 90 days. Four neonates died while in the NICU (all syndromatic). In the remaining 16 cases, treatment began as early as medically possible. The first cast was applied within the first week of life in 14 cases. A total of 75 casts were applied during the study period. Three casts (4%) were removed because of leg edema or a need for venous access. Casts were routinely replaced every 4-7 days. Achilles tenotomies were performed in the NICU for babies achieving satisfactory correction. At last follow-up, 10 children were independent walkers and six were nonambulatory; all showed successful correction of clubfeet. The results of this study show that in most cases, clubfoot treatment is feasible and effective within the first week of life. Instances necessitating immediate cast removal are highlighted. Although while facing acute life-threatening medical problems, the treatment of clubfoot may not be considered a priority, most neonates will grow up into independent individuals; thus, every effort should be made to initiate the best clubfoot management with minimal delay.

[Body composition and metabolic risk in small for gestational age children treated with growth hormone]

BACKGROUND AND OBJECTIVES

Small for gestational age (SGA) children are at increased risk of metabolic syndrome. Our objective is to evaluate changes in body composition produced by growth hormone (GH) treatment.

PATIENTS AND METHOD

A group of 28 SGA children without catch-up growth and undergoing treatment with GH was selected for evaluation. Over the course of 3 years from the beginning of the treatment with GH, the children's body composition variables (bone mineral density [BMD], fat and lean body mass proportion) were evaluated annually with dual-energy X-ray absorptiometry. A study of correlation between metabolic and body composition variables was also made.

RESULTS

Treatment with GH produces a reduction in fat mass proportion in relation to lean body mass, decreasing from 25.94±6.09 to 22.88±5.38% (P=.034). In the abdominal regions we observe an increase in lean mass, from 1,356,91±426,71 to 2,570,96±814,36g (P=.000) and a tendency for visceral fat deposits to decrease. BMD in lumbar vertebrae improved from -1.55±0.68 to -0.90±0.79Z (P=.019).

CONCLUSIONS

Treatment with GH produces changes in body composition, improving BMD and increasing the proportion of lean body mass with a reduction in fat mass. If these changes persisted into adulthood, they may cause a reduction in the metabolic and cardiovascular risk in this group of patients.

Impact of intra- and extrauterine growth on bone mineral density and content in the neonatal period of very-low-birth-weight infants

BACKGROUND

Very-low-birthweight infants (VLBWIs) are at high risk for suboptimal bone mineral density (BMD) and bone mineral content (BMC). Small-for-gestational-age (SGA) status also causes reduced bone mineralization in full-term infants. However, the impact of intrauterine and postnatal extrauterine growth on BMD and BMC in VLBWIs is inconclusive.

METHODS

We retrospectively investigated n=68 VLBWIs, comprising 45 appropriate-for-gestational-age (AGA) and 23 SGA infants who underwent lumbar spine dual-energy X-ray absorptiometry at term-equivalent age.

RESULTS

BMD and BMC did not differ between AGA and SGA VLBWIs. Subgroup analyses of infants with birthweight<1000 g vs 1000-1500 g, and GA<27 weeks vs ≥ 27 weeks also showed no differences in BMD and BMC between AGA and SGA infants. In contrast, infants with extrauterine growth restriction (EUGR) showed significantly lower values than those without (BMD: 0.124 ± 0.023 vs 0.141 ± 0.032 g/cm(2), P=0.02; BMC: 0.80 ± 0.26 vs 0.94 ± 0.23 g, P=0.04). There were no differences between AGA and SGA infants with EUGR. However, in the AGA cohort, infants with EUGR showed significantly lower values than those without (BMD: 0.121 ± 0.022; 0.141 ± 0.03 g/cm(2), P=0.02; BMC: 0.73 ± 0.23 vs 0.94 ± 0.23 g, P=0.005). Multiple regression analyses showed GA, weight and head circumference at birth, and weight percentile at term correlated with term BMD. Conversely, only weight percentile at term significantly correlated with term BMC.

CONCLUSION

EUGR, rather than IUGR, is a risk factor for reduced BMD and BMC in the neonatal period in VLBWIs.

Procollagen type I N-terminal peptide in preterm infants is associated with growth during the first six months post-term

OBJECTIVE

To identify growth-related collagen and bone parameters in small-for-gestational-age (SGA) and appropriate-for-gestational-age (AGA) preterm infants during the first six months post-term. In SGA preterm infants, increased growth and decreased bone acquisition, which we demonstrated previously, may be reflected by these markers.

DESIGN

Observational study within a randomized controlled trial.

PATIENTS

Thirty-three SGA (weight, length or both at birth <-2 SDS) and 98 AGA preterm infants (gestational age [median (IQR)]: 31·1 (1·6) vs 30·3 (2·0) weeks; 72·7% vs 42·9% boys).

MEASUREMENTS

Weight (g), length (cm), procollagen type I N-terminal peptide (PINP; μg/l), urinary helical peptide (UHP; μg/mmol creatinine) and alkaline phosphatase (ALP; U/l) expressed as standard deviation scores (SDS) at term age, three and six months post-term.

RESULTS

Weight and length gain during the first six months post-term and PINP SDS at term age, three months and six months post-term were higher in SGA compared with AGA infants. UHP SDS and ALP SDS were similar in SGA and AGA infants. PINP SDS and UHP SDS at term age and PINP SDS at three months were associated with subsequent weight and length gain until six months post-term.

CONCLUSIONS

Increased growth in SGA compared with AGA preterm infants is reflected by increased collagen type I synthesis during the first six months post-term, suggesting that PINP and UHP correspond with growth in preterm infants. An explanation for decreased bone acquisition of SGA preterm infants may be that increased collagen type I synthesis is not directly followed by increased bone mineralization.