Long term postnatal development of insulin secretion in early premature infants

The postnatal development of insulin secretion was studied in a group of premature infants (26-30 weeks gestation at birth) for periods up to 110 days after birth and in a small group of full-term infants (38-42 weeks gestation) for up to 47 days after birth. Circulating insulin levels were measured before, and at 30 min after the commencement of a glucose infusion given either parenterally or enterally depending on conceptual age and the mode of nutrition of the infant. The insulin response was assessed as the ratio of the increase in plasma insulin concentration to the increase in blood glucose concentration at 30 min. There was a small insulin response to glucose on day 1 in the premature infants and this increased slowly over the remainder of the study period regardless of the route of administration of glucose or of the mode of nutrition. The full-term infants were more responsive over the seven postnatal weeks in which they were studied. It is concluded that early premature infants can take up to eighteen weeks to develop an ability to respond fully to hyperglycaemia with insulin secretion even though full oral nutrition had been established over the last twelve weeks.     

Early postnatal changes in intracranial arterial blood flow velocities in term infants

A range-gated Doppler technique was used to assess intracranial arterial blood flow velocity changes in 20 healthy term infants during the first 3 days after birth. Systolic, diastolic, and mean flow velocity decreased during the first 30 min after birth whereas arterial pressure and heart rate did not change. Mean flow velocity did not change from 30 min to 72 h of life, although systolic and diastolic flow velocity changed in opposite directions. Systolic flow velocity increased to 2 h of age and thereafter decreased. Diastolic flow velocity decreased to a minimum value at 2 h and thereafter increased to 24 h of age. These flow velocity changes suggest an initial decrease in cerebral perfusion, followed by a constant cerebral blood flow during normal circulatory transition after birth.     

Serum adiponectin concentrations in newborn infants in early postnatal life

Serum adiponectin levels were investigated in 28 small-for-gestational-age (SGA) and 34 appropriate-for-gestational-age (AGA) term neonates to examine how fetal growth correlates with adiponectin levels. A blood sample for determination of adiponectin was obtained during the first 24 h of life. The levels of serum adiponectin were significantly higher in all newborn infants than in healthy children (28.7 +/- 17.0 versus 9.3 +/- 6.1 microg/mL; p < 0.01). There was a significant difference in adiponectin levels between SGA and AGA infants (23.2 +/- 14.8 versus 33.2 +/- 17.5 microg/mL; p=0.02). For all of the newborn groups, serum adiponectin levels correlated positively with birth weight (r=0.27, p <0.05) and head circumference (r=0.30, p <0.05). There was no relationship between serum adiponectin levels and gestational age, birth length, blood glucose levels, or blood sampling time after birth. There was no gender difference in adiponectin levels in the entire newborn group (30.0 +/- 19.7 versus 28.0 +/- 15.5 microg/mL, in male and female infants). Our results suggest that hyperadiponectinemia and a positive relationship between the serum levels of adiponectin and birth weight in newborns cannot be explained by the low percentage of body fat alone. Lower adiponectin levels in SGA infants than in AGA infants are unlikely to suggest insulin resistance in intrauterine growth-retarded infants in early postnatal life but may be a predisposing factor in the future development of insulin resistance or type 2 diabetes.     

Water, energy and early postnatal growth in preterm infants

Non-invasive methods, including stable isotope techniques, indirect calorimetry, nutritional balance and skinfold thickness, have given a new insight into early postnatal growth in neonates. Neonates and premature infants in particular, create an unusual opportunity to study the fluid and metabolic adaptation to extrauterine life because their physical environment can be controlled, fluid and energy balance can be measured and the link between metabolism and the energetics of their postnatal growth can be assessed accurately. Thus the postnatal time course of total body water, heat production, energy cost of growth and composition of weight gain have been quantified in a series of "healthy" low-birth-weight premature infants. These results show that total body water is remarkably stable between postnatal days 3-21. Energy expenditure and heat production rates increase postnatally from mean values of 40 kcal/kg/day during the first week to 60 kcal/kg/day in the third week. An apparent energy balance deficit of 180 kcal/kg can be ascribed to premature delivery. The cost of protein metabolism is the highest energy demanding process related to growth. The fact that nitrogen balance becomes positive within 72 h after birth places the newborn in a transitional situation of dissociated balance between energy and protein metabolism during early postnatal growth: skinfold thickness, dry body mass and fat decrease, while there is a gain in protein and increase in supine length. This particular situation ends during the second postnatal week and soon thereafter the rate of weight gain matches statural growth. The goals of the following review are to summarize data on total body water and energy metabolism in premature infants and to discuss how they correlate with physiological aspects of early postnatal growth     

The postnatal hypotransferrinemia of early preterm newborn infants.

Preterm newborns were found to be markedly hypotransferrinemic when compared with normal term infants. At birth the concentration of transferrin in sera from preterm infants of gestational age equal to or less than 32 weeks is 45% of that found in normal term infant sera. The preterm infant transferrin levels slowly rise so that 7-8 weeks after birth they are 78% of the level found in the sera of normal term infants. We also found that the serum transferrin concentrations at birth correlate with gestational age. Therefore, the transferrin levels postnatally in early preterm infants reflect postconceptional rather than postnatal age.     

Adrenal function in very preterm infants in the early postnatal period]

In very premature infants of less than 30 weeks gestational age there is no correlation between the severity of illness and plasma cortisol concentrations. Low plasma cortisol levels were measured during critical illness with severe arterial hypotension requiring catecholamine treatment in the first two weeks of life. Thus, a relative adrenal insufficiency is suspected. The pituitary responds to CRH and the adrenal cortex to ACTH. But it is still questionable, wether the response is sufficient. Preterm infants with an impaired adrenal function in the first weeks of life seem to be at a higher risk for developing bronchopulmonary dysplasia. Steroids are effective in the treatment of arterial hypotension and bronchopulmonary dysplasia. Because of the broad spectrum of severe and long-term adverse effects, the treatment with glucocorticoids is recommended only after carefully balancing its benefits and risks.     

Early postnatal skin colour changes in term newborns with subclinical histological chorioamnionitis

Chorioamnionitis, a known risk factor for fetal and neonatal morbidity both in preterm and term newborns, is often subclinical. Earlier observations have linked skin colourimetry to neonatal illness severity and adverse neonatal outcome. Here, we tested the hypothesis that subclinical histological chorioamnionitis is associated with early postnatal skin colour changes in term newborns. Skin colourimetry on ten body sites (forehead, cheek, forearm, palm, upper chest, abdomen, back, buttock, leg, and sole) was examined in 45 term infants with subclinical histological chorioamnionitis and 45 sex- and gestational age-matched controls, using a tristimulus portable colourimeter at 1, 5 and 10 min after birth. Infants with subclinical histological chorioamnionitis showed statistically significant early postnatal skin colourimetric differences, in nine and seven out of the ten body sites examined as compared to control newborns at 1 min (P0.0092), 5 min (P0.0081) and 10 min (P0.0056) from birth, respectively. Skin colourimetry changes were associated with lower 1 min Apgar scores (P<0.0001), cord blood pH (P<0.0001), PaO₂ (P<0.0001), and base excess (P<0.0001) values, together with higher cord blood PaCO₂ (P=0.0001), NICU admissions (P=0.00076), endotracheal intubation in the delivery room (P=0.012), Neonatal Acute Physiology-Perinatal Extension (P<0.0001) and Neonatal Therapeutic Intervention Scoring System (P<0.0001) scores than the chorioamnionitis-negative infants. Conclusion:these findings, compatible with early peripheral microcirculatory changes, indicate skin vasoconstriction as an early neonatal manifestation of subclinical chorioamnionitis.Abbreviations CA chorioamnionitis - NTISS Neonatal Therapeutic Intervention Scoring System - s-HCA subclinical histological chorioamnionitis - SNAP-PE Score for Neonatal Acute Physiology-Perinatal Extension     

Determinants of adiposity during preweaning postnatal growth in appropriately grown and growth-restricted term infants

The distribution and quantity of adipose tissue are markers of morbidity risk in children and adults. Poor intrauterine growth and accelerated postnatal growth are believed to add to these risks. The aim of this study was to assess adipose tissue content and distribution at birth and 6 wk in relation to intrauterine growth restriction, postnatal growth, and infant diet. We measured weight, length, and head circumference and adipose content and distribution using magnetic resonance imaging at 6 wk of age in appropriately grown for gestational age (AGA) and growth-restricted (GR) infants and compared this with birth data. By 6 wk, GR infants showed complete catch-up in comparison to AGA infants in relation to head growth and adiposity. Catch-up in length and weight was not complete. Accelerated linear growth, but not accelerated weight gain, was associated with a highly significant increase in adiposity (r = 0.57, p = 0.001) regardless of AGA/GR status. The highest adiposity at 6 wk, allowing for baseline variables and linear growth, was seen in exclusively breast-fed GR infants (mean, 95% confidence interval: 33.5%, 29.51-37.5). Adipose tissue distribution remained constant and was unrelated to growth and diet. Reduced birth adiposity (B = -0.185, p = 0.003), but not low birth head size (B = 0.32, p = 0.093), was a significant predictor of accelerated postnatal head growth (R(2) = 0.29, adjusted R(2) = 0.23, p = 0.012). Increasing adiposity appears to be an inevitable accompaniment of accelerated linear growth. Low total adipose tissue quantity at birth appears to direct nutrition toward head growth. Adipose tissue may be involved in the signaling of catch-up growth.     

Early postnatal changes in the perfusion index in term newborns with subclinical chorioamnionitis

BACKGROUND: Chorioamnionitis (HCA) in term newborns is often subclinical and associated with neonatal morbidity and mortality. OBJECTIVE: To assess the value of the pulse oximetry perfusion index (PI) in the early prediction of subclinical HCA in term newborns. METHODS: PI cut-off values were first identified in 51 term newborns with HCA and 115 matched controls, retrospectively categorised on the basis of placental histology (study phase 1). The PI thresholds obtained were subsequently tested on an unselected case series of 329 prospectively recruited, term newborns (study phase 2). PI was evaluated during the first five minutes after delivery. Initial illness severity and short term clinical outcomes were determined. RESULTS: In study phase 1, newborns with HCA had lower PI one and five minutes (p<0.0001) after delivery, lower one minute Apgar score (p = 0.017), lower cord blood base excess (p = 0.0001), together with higher rates of admission to neonatal intensive care unit (p = 0.0001) and endotracheal intubation (p = 0.017), and higher SNAP-PE (p<0.0001) and NTISS (p<0.0001) scores than those without HCA. In the prospective validation phase of the study, the PI cut-off values generated (one minute < or =1.74, five minutes < or =2.18) showed 100% sensitivity, 99.4% specificity, 93.7% positive predictive value, and 100% negative predictive value in identifying subclinical HCA. Early identification of HCA was associated with a decreased rate of admission to intensive care (p = 0.012), as well as lower initial illness severity (p< or =0.0001) and therapeutic intensity (p = 0.0006) than the newborns with HCA in phase 1. CONCLUSION: These findings suggest that early PI monitoring is helpful in identifying HCA in term newborns.     

Contrasts in brainstem function between normal and high-risk infants in early postnatal life

Brainstem auditory evoked potentials (BAEPs) were recorded from healthy and high-risk infants at selected ages throughout their first year of life. Amplitude and latency measurements of peaks I, III and V were treated in a series of multivariate analyses of variance. Significant main effects for age (newborn, 3 wk, 6 wk, 3 mth, 6 mth and 1 yr), group (healthy, risk) and peaks (amplitude and latency of BAEP waves I, III and V) were observed. In addition, the interaction between these factors proved statistically significant. As expected, the pattern of response amplitude and latency for the various peaks differed as a function of age. Moreover, healthy and risk infants revealed different maturational trends. These results indicate that infants born ‘at risk’ but free of severe auditory deficits and major neurological difficulties can be distinguished from healthy (age-matched) controls in terms of the BAEP throughout the first postnatal year.     

Adrenocortical steroids in small-for-gestational-age term infants during the early neonatal period

We evaluated adrenocortical steroid concentrations at birth and during postnatal adaptation (2 h until 7 days) in 10 vaginally delivered term small-for-gestational-age (SGA) infants and 12 term appropriate-for-gestational age infants. Plasma aldosterone, 11-deoxycorticosterone, corticosterone, progesterone, 17-hydroxyprogesterone, 11-deoxycortisol, cortisol, and cortisone were longitudinally measured by specific RIA after Sephadex LH-20 chromatography. Mean aldosterone was significantly higher in SGA than in appropriate-for-gestational-age infants (2 h to 7 days; p less than 0.001). In SGA infants, cortisone and cortisol levels were significantly lower in umbilical artery (p less than 0.05), and all glucocorticoid levels were significantly lower 12 h after birth (p less than 0.05). Thereafter (24 h to 7 days), only 11-deoxycortisol levels remained significantly lower in SGA; corticosterone and cortisol levels were even higher (p less than 0.05) in SGA 24 h after birth. The data suggest that SGA infants maintain high aldosterone levels throughout the 1st wk of life. Low cortisol and cortisone levels in umbilical artery as well as low glucocorticoid levels at 2 h and/or 12 h compared to term appropriate-for-gestational-age infants may reflect either a less stressful postnatal adaptation or, more likely, a reduced adrenocortical synthesis in term SGA infants.     

State of the antioxidant system in premature newborn infants during early postnatal period

The main parameters of the antioxidant system--AOS (glutathione peroxidase, glutathione reductase, superoxide dismutase, ceruloplasmin, estriol, estradiol) were studied in 58 normal full-term infants and in 178 premature infants in the course of the early neonatal period. In the control group, the functioning of the AOS appeared more perfect and was characterized by phasic changes in the course of the first week of life. The premature infants demonstrated functional disorganization of both enzymatic (glutathione in particular) and hormonal components of the system of antiperoxide defence. This circumstance played a substantial part in the development of polysaturated fatty acids deficiency, which determined in turn the modification of the membrane lipid content and selective loss of cell sensitivity to neuro-humoral actions and unbalance in the system of cyclic nucleotides.     

Influence of early postnatal dexamethasone therapy on ventilator dependency in surfactant-substituted preterm infants

We examined 26 preterm infants with respiratory distress syndrome in a randomized controlled prospective study to determine whether early postnatal dexamethasone therapy (<2h; 0.5 mg/kg per day) over 5 days in addition to substitution of surfactant (100 mg/kg) facilitates extubation and the course of RDS. Control ( n = 12) and treated ( n = 14) groups were comparable in birthweight (mean ± SD: 1219 ± 292 versus 1446 ± 442g), gestational age (29.3 ± 2.2 versus 30.6 ± 2.7 weeks), prenatal characteristics and initial respiratory and blood gas parameters. In both groups one infant died. Infants in the dexamethasone group responded better to surfactant (12/14 versus 3/12; p < 0.01), were extubated earlier (6.6 versus 14.2 days; p < 0.02) and required less time on supplemental oxygen (4.2 versus 12.5 days; p < 0.02). Pulmonary complications tended to be lower in the dexamethasone group (1/14 versus 4/12), as was the frequency of retinopathy (2/14 versus 6/12; p < 0.05). We conclude that early postnatal dexamethasone therapy improves response to surfactant therapy resulting in better weaning and earlier extubation in premature infants.     

Kernicterus in term infants

Kernicterus is a frequent occurrence in Chinese term infants. In a previous study, the mean level of serum bilirubin of 152 kernicteric infants was 35.4 mg/dl (605.3 μmol/l) and the range was 22.3-50 mg/dl. More recently, three further term infants developed kernicterus and one exhibited bilirubin level of only 23.3 mg/dl. Features of haemolysis were lacking in 56.8% of these infants. Evidence of brain damage occurred in 26.5% in a former series and in 5.5% of the more recent study of those infants who developed bilirubinaemia exceeding 20 mg/dl. Such a high risk favours the present practice of exchange transfusion for rising bilirubin beyond 20 mg/dl (342 μmol/l) in Chinese term infants.