Effect of intrauterine growth retardation on postnatal weight change in preterm infants

Higher versus lower sodium intake for preterm infants

BACKGROUND

Infants born preterm are at increased risk of early hypernatraemia (above-normal blood sodium levels) and late hyponatraemia (below-normal blood sodium levels). There are concerns that imbalances of sodium intake may impact neonatal morbidities, growth and developmental outcomes.

OBJECTIVES

To determine the effects of higher versus lower sodium supplementation in preterm infants.

SEARCH METHODS

We searched CENTRAL in February 2023; and MEDLINE, Embase and trials registries in March and April 2022. We checked reference lists of included studies and systematic reviews where subject matter related to the intervention or population examined in this review. We compared early (< 7 days following birth), late (≥ 7 days following birth), and early and late sodium supplementation, separately.

SELECTION CRITERIA

We included randomised, quasi-randomised or cluster-randomised controlled trials that compared nutritional supplementation that included higher versus lower sodium supplementation in parenteral or enteral intake, or both. Eligible participants were preterm infants born before 37 weeks' gestational age or with a birth weight less than 2500 grams, or both. We excluded studies that had prespecified differential water intakes between groups.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed eligibility and risk of bias, and extracted data. We used the GRADE approach to assess the certainty of evidence.

MAIN RESULTS

We included nine studies in total. However, we were unable to extract data from one study (20 infants); some studies contributed to more than one comparison. Eight studies (241 infants) were available for quantitative meta-analysis. Four studies (103 infants) compared early higher versus lower sodium intake, and four studies (138 infants) compared late higher versus lower sodium intake. Two studies (103 infants) compared intermediate sodium supplementation (≥ 3 mmol/kg/day to < 5 mmol/kg/day) versus no supplementation, and two studies (52 infants) compared higher sodium supplementation (≥ 5 mmol/kg/day) versus no supplementation. We assessed only two studies (63 infants) as low risk of bias. Early (less than seven days following birth) higher versus lower sodium intake Early higher versus lower sodium intake may not affect mortality (risk ratio (RR) 1.02, 95% confidence interval (CI) 0.38 to 2.72; I2 = 0%; 3 studies, 83 infants; low-certainty evidence). Neurodevelopmental follow-up was not reported. Early higher versus lower sodium intake may lead to a similar incidence of hyponatraemia < 130 mmol/L (RR 0.68, 95% CI 0.40 to 1.13; I2 = 0%; 3 studies, 83 infants; low-certainty evidence) but an increased incidence of hypernatraemia ≥ 150 mmol/L (RR 1.62, 95% CI 1.00 to 2.65; I2 = 0%; 4 studies, 103 infants; risk difference (RD) 0.17, 95% CI 0.01 to 0.34; number needed to treat for an additional harmful outcome 6, 95% CI 3 to 100; low-certainty evidence). Postnatal growth failure was not reported. The evidence is uncertain for an effect on necrotising enterocolitis (RR 4.60, 95% CI 0.23 to 90.84; 1 study, 46 infants; very low-certainty evidence). Chronic lung disease at 36 weeks was not reported. Late (seven days or more following birth) higher versus lower sodium intake Late higher versus lower sodium intake may not affect mortality (RR 0.13, 95% CI 0.01 to 2.20; 1 study, 49 infants; very low-certainty evidence). Neurodevelopmental follow-up was not reported. Late higher versus lower sodium intake may reduce the incidence of hyponatraemia < 130 mmol/L (RR 0.13, 95% CI 0.03 to 0.50; I2 = 0%; 2 studies, 69 infants; RD -0.42, 95% CI -0.59 to -0.24; number needed to treat for an additional beneficial outcome 2, 95% CI 2 to 4; low-certainty evidence). The evidence is uncertain for an effect on hypernatraemia ≥ 150 mmol/L (RR 7.88, 95% CI 0.43 to 144.81; I2 = 0%; 2 studies, 69 infants; very low-certainty evidence). A single small study reported that later higher versus lower sodium intake may reduce the incidence of postnatal growth failure (RR 0.25, 95% CI 0.09 to 0.69; 1 study; 29 infants; low-certainty evidence). The evidence is uncertain for an effect on necrotising enterocolitis (RR 0.07, 95% CI 0.00 to 1.25; 1 study, 49 infants; very low-certainty evidence) and chronic lung disease (RR 2.03, 95% CI 0.80 to 5.20; 1 study, 49 infants; very low-certainty evidence). Early and late (day 1 to 28 after birth) higher versus lower sodium intake for preterm infants Early and late higher versus lower sodium intake may not have an effect on hypernatraemia ≥ 150 mmol/L (RR 2.50, 95% CI 0.63 to 10.00; 1 study, 20 infants; very low-certainty evidence). No other outcomes were reported.

AUTHORS' CONCLUSIONS

Early (< 7 days following birth) higher sodium supplementation may result in an increased incidence of hypernatraemia and may result in a similar incidence of hyponatraemia compared to lower supplementation. We are uncertain if there are any effects on mortality or neonatal morbidity. Growth and longer-term development outcomes were largely unreported in trials of early sodium supplementation. Late (≥ 7 days following birth) higher sodium supplementation may reduce the incidence of hyponatraemia. We are uncertain if late higher intake affects the incidence of hypernatraemia compared to lower supplementation. Late higher sodium intake may reduce postnatal growth failure. We are uncertain if late higher sodium intake affects mortality, other neonatal morbidities or longer-term development. We are uncertain if early and late higher versus lower sodium supplementation affects outcomes.

Serial head circumference measurements should be used to classify congenital microcephaly

BACKGROUND

Measuring the maximum occipitofrontal circumference only once at birth or within 24 h after birth may lead to misclassifications of microcephaly. This study compared the head circumference (HC) of newborns at birth or within 24 h after birth to their third day of life (DOL3) as well as evaluated maternal- and infant-specific factors associated with increased HC by DOL3.

METHODS

This prospective study included 1131 live births between February and May 2019 with a gestational age > 27 weeks. All newborns had their HC measured at birth or within 24 h after birth as well as on DOL3 before discharge. HC measurements were performed by trained personnel using non-elastic tape measures. The World Health Organization (WHO) and Fenton Growth Charts were used as reference ranges for interpretation of full-term and preterm neonates, respectively.

RESULTS

Paired sample t-test analyses found a statistically significant increase in HC measured on the DOL3 compared with HCs of the same newborns at birth or within 24 h of birth. The mean HC increase was 0.17 cm (95% confidence interval [0.13, 0.21], P < 0.001). The mean ± standard deviation HC within 24 h of birth and at DOL3 were 33.58 ± 1.53 cm and 33.75 ± 1.37 cm, respectively. Thirty-two newborns had HCs less than the third percentile (< P3) at birth, 25 of which had HC ≥ P3 at DOL3. After adjusting for mode of and presentation at delivery, newborns whose mothers experienced labor pains (β = 0.31, P < 0.001) and were either symmetrically (β = 0.59, P = 0.002) or asymmetrically small-for-gestational age (SGA; β = 0.37, P = 0.03) had significantly increased HC at DOL3. On average, newborns whose mothers experienced labor pain had 0.31 cm increases in HC at DOL3. Symmetrical SGA newborns also had an average 0.59 cm increase in HC at DOL3. Parity and gestational age were not associated with changes in HC.

CONCLUSIONS

Serial HC measurements on DOL3 or before newborns' discharge is crucial to classifying congenital microcephaly.

Postnatal maximal weight loss, fluid administration, and outcomes in extremely preterm newborns

OBJECTIVE

Evaluate maximal weight loss (MWL) and total fluid administration (TFA) association in first week after birth with outcomes among extremely preterm (EP) newborns.

STUDY DESIGN

We performed a retrospective analysis of the Preterm Erythropoietin Neuroprotection Trial evaluating first-week MWL, TFA, and association with in-hospital outcomes.

RESULTS

Among n = 883 included EP neonates, n = 842 survived ≥ 7 days and were included in outcome analyses. MWL between 5% to 15% was associated with decreased odds of necrotizing enterocolitis compared to MWL > 15% (OR 0.49, 95% CI 0.25-0.98). Average TFA > 150 mL/kg birthweight/day was associated with increased odds of necrotizing enterocolitis (OR 3.22, 95% CI 1.40-7.42) and patent ductus arteriosus requiring surgery (OR 2.14, 95% CI 1.10-4.15).

CONCLUSION

MWL between 5% to 15% is a potentially optimal window of MWL. Increasing average TFA in the first week is associated with adverse neonatal outcomes. Prospective studies evaluating MWL and TFA and relationship to outcomes in EP neonates are needed.

CLINICAL TRIAL REGISTRATION

This study is a secondary analysis of pre-existing data from the PENUT Trial Registration: NCT01378273, https://clinicaltrials.gov/ct2/show/NCT01378273 .

Development of an imputation model to recalibrate birth weights measured in the early neonatal period to time at delivery and assessment of its impact on size-for-gestational age and low birthweight prevalence estimates: a secondary analysis of a pregnancy cohort in rural Nepal

OBJECTIVES

In low-income countries, birth weights for home deliveries are often measured at the nadir when babies may lose up of 10% of their birth weight, biasing estimates of small-for-gestational age (SGA) and low birth weight (LBW). We aimed to develop an imputation model that predicts the 'true' birth weight at time of delivery.

DESIGN

We developed and applied a model that recalibrates weights measured in the early neonatal period to time=0 at delivery and uses those recalibrated birth weights to impute missing birth weights.

SETTING

This is a secondary analysis of pregnancy cohort data from two studies in Sarlahi district, Nepal.

PARTICIPANTS

The participants are 457 babies with daily weights measured in the first 10 days of life from a subsample of a larger clinical trial on chlorhexidine (CHX) neonatal skin cleansing and 31 116 babies followed through the neonatal period to test the impact of neonatal massage oil type (Nepal Oil Massage Study (NOMS)).

OUTCOME MEASURES

We developed an empirical Bayes model of early neonatal weight change using CHX trial longitudinal data and applied it to the NOMS dataset to recalibrate and then impute birth weight at delivery. The outcomes are size-for-gestational age and LBW.

RESULTS

When using the imputed birth weights, the proportion of SGA is reduced from 49% (95% CI: 48% to 49%) to 44% (95% CI: 43% to 44%). Low birth weight is reduced from 30% (95% CI: 30% to 31%) to 27% (95% CI: 26% to 27%). The proportion of babies born large-for-gestational age increased from 4% (95% CI: 4% to 4%) to 5% (95% CI: 5% to 5%).

CONCLUSIONS

Using weights measured around the nadir overestimates the prevalence of SGA and LBW. Studies in low-income settings with high levels of home births should consider a similar recalibration and imputation model to generate more accurate population estimates of small and vulnerable newborns.

The association of early postnatal weight loss with outcome in extremely low birth weight infants

BACKGROUND

To compare outcomes of extremely low birth weight (ELBW) infants having different weight losses in the first 3 days of life.

METHODS

One hundred and twenty six ELBW infants were evaluated retrospectively for weight loss percentages on the third day of life compared to their birth weight. We examined the weight loss on the third day of life compared to the birth weight for the ELBW infants and tested its association with mortality and morbidities. The mortality was subgrouped as overall mortality and mortality in the first 7 days of life. The morbidities were patent ductus arteriosus (PDA), intraventricular hemorrhage (IVH) and bronchopulmonary dysplasia (BPD). BPD was defined as need for supplemental oxygen at 36 weeks' postconceptional age. We grouped the infants into four quartiles according to weight loss percentage on the third day of life: Group 1 (Quartile 1), infants with weight loss of 0-3% of birth weight; Group 2 (Quartile 2); infants with weight loss of 3.1-7.5%, Group 3 (Quartile 3), infants with weight loss of 7.51-12%; and Group 4 (Quartile 4), infants with weight loss of more than 12%. The mortality and morbidities were analyzed according to these groups and other risk factors.

RESULTS

Overall mortality and mortality in the first 7 days of life were significantly higher in Groups 1 (36% and 27%) and 4 (43% and 24%), compared to Groups 2 (10% and 10%) and 3 (18% and 9%), respectively.

CONCLUSION

Weight loss less than 3% and more than 12% was significantly associated with an increase in mortality. There was a positive correlation between weight loss on the third day of life and IVH.

CONCLUSION

Inappropriate weight loss in ELBW infants is associated with increased mortality and IVH. Appropriate weight loss can improve outcomes in this population.

Is term newborn body composition being achieved postnatally in preterm infants?

BACKGROUND

The American Academy of Pediatrics (AAP) recommends that preterm infants' growth duplicates fetal growth rates and that body composition replicates in utero body composition.

AIMS

To compare the total body fat mass between preterm infants assessed at term corrected age and full-term newborns, and to investigate the effects of gestational age, gender, weight increase, being breast fed on total adiposity.

STUDY DESIGN

Prospective observational study.

SUBJECTS

One hundred and ten preterm infants [mean (SD) gestational age: 29.9 (2.3) weeks; birth weight: 1118 (274) g], and 87 full term [mean (SD) 38.6 (1.21) weeks, 3203 (385) g], breastfed infants.

OUTCOME MEASURES

Growth and body composition by means of a pediatric air displacement system were assessed at term corrected age in preterm infants and on day 3 of life in full term infants.

RESULTS

Weight, length and head circumference were smaller in the preterm group as compared to the term group. Mean (SD) percentage of fat mass in preterm infants was significantly higher as compared to term infants [14.8 (4.4) vs 8.59 (3.71), P<0.0001]. Fat mass was negatively correlated with gestational age (P<0.001), and positively associated with weight increase (P< 0.05).

CONCLUSIONS

Our data suggest that body composition, in terms of fat mass, in preterm infants at term corrected age is different from that of full term newborns.

Total body water in small- and appropriate- for gestational age newborns

OBJECTIVES

To ascertain total body water in small for gestational age (SGA) and appropriate for gestational age (AGA) newborns.

METHODS

SGA and AGA babies were matched by gestational age and studied from birth to term age. Criteria for exclusions were genetic syndromes, malformations, and congenital infections. Bioelectrical impedance was performed at two days of life (term infants), or at seven days of life and term age (preterm infants). Weight and length were measured by trained interviewers, and Z-score, weight/length ratio and Rohrer ponderal index was calculated.

RESULTS

Of the 54 infants evaluated, 28 were SGA (17 preterm) and 26 were AGA (15 preterm). Total body water was greater in SGA preterm babies at seven days of age (P=0.058) and at term age (P<0.0001). Weight/length ratio and Rohrer ponderal index increased towards term. Weight Z-score and anthropometric measures at term were significantly smaller in SGA babies. Being SGA and variation in Rohrer ponderal index influenced the variations in total body water.

CONCLUSIONS

SGA babies had greater total body water, and both groups presented insufficient increase in body solid mass, stressing the importance of nutritional support during neonatal care.

Weight loss and bronchopulmonary dysplasia in very low birth weight infants

Our objective was to evaluate the extent of weight loss in very low birth weight (VLBW) preterm infants and to discover how weight loss and other variables correlate with bronchopulmonary dysplasia (BPD). We conducted an observational study of 387 VLBW preterms, gestational age (GA) < 33 weeks, in a single institution over a period of 5 years. The mean weight loss of AGA infants was significantly greater than that of SGA infants. In AGA infants, GA, z-score, weight loss, and male sex were found to correlate with BPD. After adjustments were made for GA and birth weight, each 10% loss of body weight increased the risk for developing BPD by a factor of 2.7. We concluded that excessive weight loss does not prevent BPD in VLBW preterms and presumably should be prevented. Controlled fluid restriction resulting in milder weight loss is probably the right choice.

Association between early postnatal weight loss and death or BPD in small and appropriate for gestational age extremely low-birth-weight infants

OBJECTIVE

To examine the association between weight loss during the first 10 days of life and the incidence of death or bronchopulmonary dysplasia (BPD) in small for gestational age (SGA) and appropriate for gestational age (AGA) extremely low-birth-weight infants.

DESIGN/METHODS

This is a retrospective analysis of a cohort of ELBW (birth weight <1000 g) infants from the NICHD Neonatal Research Network's database. The cohort consisted of 9461 ELBW infants with gestational age of 24-29 weeks, admitted to Network's participating centers during calendar years 1994-2002 and surviving at least 72 h after birth. The cohort was divided into two groups, 1248 SGA (with birth weight below 10th percentile for gestational age) and 8213 AGA (with birth weight between 10th and 90th percentile) infants. We identified infants with or without weight loss during the first 10 days of life, which we termed as 'early postnatal weight loss' (EPWL). Univariate analyses were used to predict whether EPWL was related to the primary outcome, death or BPD, within each birth weight/gestation category (SGA or AGA). BPD and death were also analyzed separately in relation to EPWL. Logistic regression analysis was done to evaluate the risk of death or BPD in SGA and AGA groups, controlling for maternal and neonatal demographic and clinical factors found to be significant by univariate analysis.

RESULTS

SGA ELBW infants had a lower prevalence of EPWL as compared with AGA ELBW infants (81.2 vs 93.7%, respectively, P<0.001). In AGA infants, univariate analysis showed that death or BPD rate was lower in the group of infants with EPWL compared with infants without EPWL (53.4 vs 74.3%, respectively, P<0.001). The BPD (47.2 vs 64%, P<0.001) and death (13.8 vs 32.9%, P<0.001) rate were similarly lower in the EPWL group. The risk-adjusted odds ratios (ORs) showed that EPWL was associated with lower rate of death or BPD (OR 0.47, 95% CI: 0.37-0.60). In SGA infants, on univariate analysis, a similar association between EPWL and outcomes was seen as shown in AGA infants: death or BPD (55.9 vs 75.2%, P<0.001), BPD rate (48.3 vs 62.1%, P=0.002) and rate death (19 vs 40.8%, P<0.001) for those with or without EPWL, respectively. Multiple logistic regression showed that as in AGA ELBW infants, EPWL was associated with lower risk for death or BPD (OR 0.60, 95% CI: 0.41-0.89) among SGA infants.

CONCLUSIONS

SGA infants experienced less EPWL when compared with their AGA counterparts. EPWL was associated with a lower risk of death or BPD in both ELBW AGA and SGA infants. These data suggest that clinicians who consider the association between EPWL and risk of death or BPD should do so independent of gestation/birth weight status.

Fetal growth and postnatal growth failure in very-low-birthweight infants

AIM

To determine in a cohort of very-low-birthweight (VLBW) infants the incidence of postnatal growth failure and the influence of intrauterine growth and neonatal morbidities on the risk for severe postnatal growth failure (PNGF).

METHODS

The study was based on analysis of data from the Israel Neonatal Network database on VLBW infants born between 1995 and 2001. Z-score was determined for weight at birth and discharge, and severe PNGF was defined as a decline in z-score of greater than 2. Univariate analysis and multi-linear regression determined the effect of fetal growth and neonatal morbidities on the risk for severe PNGF.

RESULTS

Severe PNGF occurred in 10.6% of the cohort. The mean+/-SD birthweight (BW) z-score was -0.59+/-0.74, decreasing to -1.67+/-0.77 at discharge. The incidence of severe PNGF increased significantly with decreasing BW and gestational age. Each 1-unit increase in z-score BW was associated with a 2.37-fold increased risk for severe PNGF. Severe respiratory distress syndrome, patent ductus arteriosus, sepsis, necrotizing enterocolitis, and bronchopulmonary dysplasia were associated with severe PNGF.

CONCLUSION

Severe PNGF among VLBW infants was markedly influenced by intrauterine growth as well as major morbidities. In the assessment of postnatal growth among VLBW infants, growth status at birth should be considered.

Low birth weight infants and Calmette-Guérin bacillus vaccination at birth: community study from Guinea-Bissau

BACKGROUND

In developing countries, low birth weight (LBW) children are often not vaccinated with Calmette-Guérin bacillus (BCG) at birth. Recent studies have suggested that BCG may have a nonspecific beneficial effect on infant mortality. We evaluated the consequences of not vaccinating LBW children at birth in Guinea-Bissau.

METHODS

Between 1989 and 1999, 7138 children born at the central hospital had a birth weight registered. We assessed BCG coverage until 3 years of age. Data on tuberculin skin test (TST) for 297 children and BCG scar for 1319 children in the study population were reanalyzed for differences between normal birth weight (NBW) children and LBW children. We assessed the effect of early BCG vaccination on mortality to 12 months of age.

RESULTS

Among LBW children there were 1.5- to 3-fold more unvaccinated individuals than among NBW children up to 4 months of age. There was no overall difference between LBW and NBW children in TST or BCG scarring; LBW children vaccinated early may have had slightly reduced reactions to tuberculin. Among 845 LBW children, 182 had received BCG within the first week of life. Controlling for background factors and censoring at first diphtheria-tetanuspertussis vaccination, measles vaccination or at 6 months of age (whichever came first), the mortality rate ratio for BCG-vaccinated versus -unvaccinated LBW children was 0.17 (95% confidence interval, 0.06-0.49), with an even stronger effect for LBW children vaccinated in the first week of life (mortality rate ratio, 0.07; 95% confidence interval, 0.01-0.62).

CONCLUSIONS

The policy of not vaccinating with BCG at birth had a negative impact on vaccination coverage for LBW children. Early BCG vaccination had no large negative impact on TST and BCG scarring. Mortality was lower for BCG-vaccinated than for unvaccinated LBW children controlling for available background factors. BCG vaccination of LBW children may have a beneficial effect on survival that cannot be explained by protection against tuberculosis. Future studies should examine possible adverse effects from equalizing BCG policy for LBW and NBW children.

Longitudinal study of energy expenditure in preterm neonates <30 weeks' gestation during the first three postnatal weeks

OBJECTIVES

The objective of this study was to measure energy expenditure (EE) in a contemporary population of preterm neonates <30 weeks' gestation.

STUDY DESIGN

Prospective longitudinal cohort study in 26 consecutive preterm neonates (gestational age, 27 weeks [23-29] [median, range]; birth weight, 980 g [554-1592]). EE was measured by indirect calorimetry on postnatal days 1, 3, 5, 10, and 21. Data on body weight, energy intake, and medical therapy were prospectively collected.

RESULTS

EE increased from 121 +/- 25 kJ/kg per day (29 +/- 6 kcal/kg per day) (mean +/- SD) on day 1 to 222 +/- 25 kJ/kg per day (53 +/- 6 kcal/kg per day) on day 21. An energy deficit occurred only on day 1. EE was closely related to energy intake: For each additional kJ given, EE increased by 0.3 kJ (r = 0.789, P <.0001). Neonates with a birth weight <1000 g did not have a more pronounced energy deficit than the heavier neonates. EE during nasal continuous positive airway pressure in the first postnatal week was 25% lower than during spontaneous respiration.

CONCLUSIONS

EE could be predicted from energy intake with acceptable accuracy in preterm neonates <30 weeks' gestation during the first 3 postnatal weeks. There was no prolonged energy deficit.

In vitro validation and clinical testing of an indirect calorimetry system for ventilated preterm infants that is unaffected by endotracheal tube leaks and can be used during nasal continuous positive airway pressure

Energy expenditure measurements in ventilated preterm infants are difficult because indirect calorimetry underestimates energy expenditure during gas leaks around uncuffed endotracheal tubes routinely used in preterm infants or during nasal continuous positive airway pressure (CPAP). We, therefore, developed a breath collector that simultaneously sampled expired air expelled at the ventilator outlet and escaping via the tube leak from the infant's mouth and nose. Our breath collector was combined with a proprietary calorimeter (Deltatrac II). In vitro validation was done by methanol burning (VO(2), 13.8 mL/min; VCO(2), 9.2 mL/min) during intermittent positive pressure ventilation (IPPV) with two commonly used ventilators (Sechrist IV-100B and Infant Star). Measurement error was determined at different ventilator flows, peak inspiratory pressures of 12-24 cm H(2)O, and during a complete tube leak. The mean measurement error with both ventilators was low (VO(2) +/- 3 %, VCO(2) +/- 2 %) even during a complete tube leak and did not increase with peak inspiratory pressure. The system response time was 2 min. In vivo measurements at the bedside were performed in 25 preterm infants (body weight, 537-1402 g). Energy expenditure during IPPV was 40 +/- 9 kcal/kg per day and 46 +/- 15 kcal/kg per day during nasal CPAP. The tube leak in the preterm infants studied during IPPV was 0 to 47 %, and during nasal CPAP 84 to 97 %. In conclusion, indirect calorimetry performed with our breath collector was accurate during IPPV and nasal CPAP and was unaffected by tube leaks.

Body water content of extremely preterm infants at birth

BACKGROUND

Preterm birth is often associated with impaired growth. Small for gestational age status confers additional risk.

AIM

To determine the body water content of appropriately grown (AGA) and small for gestational age (SGA) preterm infants in order to provide a baseline for longitudinal studies of growth after preterm birth.

METHODS

All infants born at the Hammersmith and Queen Charlotte's Hospitals between 25 and 30 weeks gestational age were eligible for entry into the study. Informed parental consent was obtained as soon after delivery as possible, after which the extracellular fluid content was determined by bromide dilution and total body water by H(2)(18)O dilution.

RESULTS

Forty two preterm infants were studied. SGA infants had a significantly higher body water content than AGA infants (906 (833-954) and 844 (637-958) ml/kg respectively; median (range); p = 0.019). There were no differences in extracellular and intracellular fluid volumes, nor in the ratio of extracellular to intracellular fluid. Estimates of relative adiposity suggest a body fat content of about 7% in AGA infants, assuming negligible fat content in SGA infants and lean body tissue hydration to be equivalent in the two groups.

CONCLUSIONS

Novel values for the body water composition of the SGA preterm infant at 25-30 weeks gestation are presented. The data do not support the view that SGA infants have extracellular dehydration, nor is their regulation of body water impaired.

Intravenous nutrition and postnatal growth of the micropremie

There is a growing body of evidence that early nutritional practices may affect short-term growth and developmental outcome. In addition, they may play a role in determining adult health and disease. There is much that needs to be learned about safe and efficacious nutrient administration in the ELBW population; about techniques to assess the effect of different nutritional strategies; and about the long-term effects of these regimen or development outcome, growth, and disease.

Randomised controlled trial of postnatal sodium supplementation on body composition in 25 to 30 week gestational age infants

AIMS

To compare the effects of early and delayed sodium supplementation on body composition and body water compartments during the first two weeks of postnatal life.

METHODS

Preterm infants of 25-30 weeks' gestation were stratified and randomly assigned according to gender and gestational age, to receive a sodium intake of 4 mmol/kg/day beginning either on the second day after birth or when weight loss of 6% of birthweight had been achieved. Daily sodium intake, total fluid intake, energy intake, urine volume, and urinary sodium excretion were recorded. Total body water was measured by H(2)(18)O dilution on days 1, 7, and 14, and extracellular fluid volume by sodium bromide dilution on days 1 and 14.

RESULTS

Twenty four infants received early, and 22 delayed, sodium supplementation. There were no significant differences between the groups in body water compartments on day 1. In the delayed group, but not the early group, there was a significant loss of total body water during the first week (delayed -44 ml/kg, p=0. 048; early 6 ml/kg, p=0.970). By day 14 the delayed, but not the early group, also had a significant reduction in extracellular fluid volume (delayed -53 ml/kg, p=0.01; early -37 ml/kg, p=0.2). These changes resulted in a significant alteration in body composition at the end of the first week (total body weight: delayed 791 ml/kg; early 849 ml/kg, p=0.013). By day 14 there were once again no significant differences in body composition between the two groups.

CONCLUSIONS

Body composition after preterm birth is influenced by the timing of introduction of routine sodium supplements. Early sodium supplementation can delay the physiological loss of body water that is part of normal postnatal adaptation. This is likely to be of particular relevance to babies with respiratory distress syndrome. A tailored approach to clinical management, delaying the introduction of routine sodium supplements until there has been postnatal loss of body water, is recommended.

Postnatal body weight curves for infants below 1000 g birth weight receiving early enteral and parenteral nutrition

No body weight curves are available for preterm infants < 1000 g birth weight receiving early enteral and parenteral nutrition. Postnatal weight changes of 136 infants with a birth weight < 1000 g were analysed retrospectively. Body weight curves for the first 30 days of life were generated for five separate birth weight groups (430-599 g, 600-699 g, 700-799 g, 800-899 g, 900-999 g). All infants had received intravenous glucose and amino acids from day 1 and intravenous lipids from day 2. Enteral feeding was started on day 1. Thus caloric intake (+/-SD) was advanced to 384+/-46 kJ/kg per day (92+/-11 kcal/kg/day) in the 1st week of life. In 136 preterm infants mean postnatal weight loss was 10.1%+/-4.6% of birth weight, birth weight was regained at a mean postnatal age of 11+/-3.7 days, but significantly earlier (7.8+/-3.5 days) in the lowest compared to the highest weight group. Mean subsequent weight gain was 15.7+/-7.2 g/ kg per day. This was accomplished by exclusive enteral nutrition from day 20 (median).

CONCLUSION

Our body weight curves are more adequate to evaluate growth of preterm infants than older published reference values because they are based on infants treated according to current nutritional standards.

Influence of respiratory distress syndrome on body composition after preterm birth

AIM

To observe changes in body composition during the first week after birth, in preterm neonates with and without respiratory distress syndrome (RDS), so as to be able to provide optimal fluid and energy intake.

METHODS

Twenty four babies with RDS and 19 healthy preterm babies, with gestational ages ranging from 26-36 weeks, were studied daily for the first week after birth. Total body water (TBW) was measured using bioelectrical impedance analysis. The babies were weighed daily and a record made of fluid and energy intake. Body solids were calculated as the difference between body weight and TBW.

RESULTS

There was a highly significant reduction in body weight by the end of the week, with the RDS babies losing more than the healthy babies (RDS 7.6%; non-RDS 3.7%). There was no significant difference in the amount of TBW at birth in the babies with and without RDS (RDS 85.1%; non-RDS 85.5%) and both groups lost the same amount of body water (RDS 10.9%; non-RDS 9.9%) by the end of the first week. The amount of total body water lost was unrelated to the volume of fluid administered. There was a loss of body solids during the first day in the RDS group, but, overall, there was a highly significant increase in both groups between birth and day 7, which was greater in the healthy babies (RDS 13.0%; non-RDS 42.7%).

CONCLUSIONS

Loss of body water after birth occurs to the same extent in healthy preterm neonates and in babies with RDS and is unrelated to the volume of fluid administered. Given adequate nutritional support, an increase in body solids can accompany early postnatal weight loss and begins almost immediately after birth, in both healthy preterm babies and babies with RDS.

Direct determination of deuterium in untreated water and urine by NMR: application to DLW analysis

Determination of deuterium (D) concentration in tap water and urine is demonstrated to average error approximately 0.5% (coefficient of variation) using a 400-MHz nuclear magnetic resonance (NMR) instrument. Time domain data are obtained using 0.75-ml samples in a broadband probe. Peak areas derived from absorption and magnitude mode Fourier transforms and least-squares fitting of the time domain free induction decays (FIDs) are all investigated as means to derive D concentrations from raw data. Least-squares fits using a sum of exponentially damped sinusoids, which yields estimates for the amplitude, damping constant (relaxation time), wavelength (resulting from mixing of precession and reference frequencies), and phase for each of the two components, are shown to provide the best precision for unfiltered FID. Amplitudes are proportional to the number of spins at each frequency, as analysis of untreated urine from doubly labeled water experiments yield highly linear washout data (r2 > 0.99998) for baseline-corrected log-transformed data. The procedure is general and should extend to other body fluids with minimal modifications. These data show that least-squares curve fitting is the most precise method of quantitative NMR data reduction for a wide range of experimental conditions.