Hypernatraemia in preterm infants born at less than 27 weeks gestation

AIMS: To study the incidence of hypernatraemia (plasma sodium >145 mmol/L), identify predisposing factors to and associated complications of hypernatraemia in preterm infants born less than 27 weeks gestation in the first 5 days of life. METHODS: Preterm infants less than 27 week gestation over an 18-month period were studied by retrospective analysis of patient records. Data were collected on gestation, birthweight, sex, antenatal steroid use, phototherapy, incubator humidity, time of transfer to incubator, plasma sodium, urea and creatinine. Actual fluid and sodium intake was calculated for the first 5 days of life. Data were collected on chronic lung disease, patent ductus arteriosus, intraventricular haemorrhage, necrotising enterocolitis and death. RESULTS: In this study 46 (69.7%) of 66 infants studied developed hypernatraemia (>145 mmol/L), occurring most frequently between 24 and 48 h of age. The median gestation of hypernatraemic babies was significantly lower. There was no significant difference in median birthweight, or factors associated with increased insensible water loss between the hypernatraemic and the non-hypernatraemic groups. Fluid intake was significantly higher on days 2, 3 and 4 in the hypernatraemic group. There was no difference in sodium intake between the two groups. More hypernatraemic babies compared with controls developed chronic lung disease, patent ductus arteriosus, significant intraventricular haemorrhage, necrotising enterocolitis and died, but was not significant. CONCLUSION: Hypernatraemia occurs commonly in preterm infants less than 27 weeks gestation and was not associated with significant morbidity. The more immature infants developed hypernatraemia and all cases resolved after increasing fluid intake.     

Plasma aldosterone levels in the 1st week of life in infants of less than 30 weeks gestation

Plasma aldosterone levels were measured in 50 infants of less than 30 weeks gestation at 24 h (D1) and 7 days (D7). The relationship between the plasma aldosterone level and a number of clinical and biochemical variables was explored. Plasma aldosterone levels ranged from 1000 to 30000 pmol/l and were inversely correlated with the severity of illness (D1 or D7), serum sodium (D7) and 24 h sodium intake (D1). No correlation with the serum potassium level was noted. Conclusion:Plasma aldosterone levels in this extremely premature cohort were significantly greater than those reported in more mature infants. Important determinants were severity of illness and sodium homeostasis.     

Neonatal hypoglycaemia in infants of diabetic mothers

OBJECTIVE: To determine whether umbilical cord blood glucose correlates with subsequent hypoglycaemia after birth in infants of well-controlled diabetic mothers. METHODOLOGY: Thirty-eight term infants of well-controlled diabetic mothers were enrolled. Five mothers had pre-existing diabetes. Of the 33 gestational diabetic mothers, 16 were managed on insulin and 17 on diet. Maternal blood glucose was maintained between 4 and 8 mmol/L during labour and delivery. Infants' plasma glucose levels were measured from venous cord blood and serially, at less than 30 min, 1 h and 2 h of life by glucose hexokinase method. Blood glucose levels were further monitored by bedside Dextrostix for 24 h. RESULTS: Eighteen (47%) infants developed hypoglycaemia (blood glucose level less than 2 mmol/L) during the first 2 h of life. There was no difference in the cord blood glucose levels between infants with or without hypoglycaemia (3.7 +/- 1.1 vs 4.5 +/- 1.1 mmol/L, respectively). Infants of mothers with diabetes diagnosed prior to 28 weeks gestation were at a higher risk of developing hypoglycaemia (8 of 10 vs 10 of 28, OR 7.2, 95%CI 1.3-40.7). Hypoglycaemic infants were of significantly higher birthweight, and were more likely to be born to Caucasian mothers and by Caesarean section. Raised maternal fructosamine blood level, the need for insulin treatment or the infant's haematocrit were not different between infants with or without hypoglycaemia. CONCLUSIONS: In well-controlled diabetic mothers, the incidence of early hypoglycaemia in infants is still high, particularly in those mothers who had a longer duration of diabetes. Cord blood glucose level did not identify the infants with hypoglycaemia.     

Incidence of retinopathy of prematurity requiring treatment in infants born greater than 30 weeks' gestation and with a birthweight greater than 1250 g from 1998 to 2002: a regional study

AIM: To ascertain the prevalence of significant Retinopathy of Prematurity (ROP) and ROP requiring treatment in infants born greater than 30 weeks gestation and with a birthweight greater than 1250 g, utilising the Neonatal Intensive Care Units' (NICUS) data collection from 1998 to 2002. Second, to determine whether infants delivered at more than 30 weeks gestation or with a birthweight greater than 1250 g require ROP screening. METHODS: A review of the New South Wales and Australian Capital Territory NICUS data collection from 1998 to 2002 was performed. Infants of gestational age 31-33 weeks and with a birthweight greater than 1250 g were included. A review was performed of these infants to ascertain stage of ROP, threshold disease and treatment for ROP. RESULTS: 2292 infants were greater than 30 weeks and had a birthweight greater than 1250 g. Of these 1386 (60%) were not examined or died prior to eye examination. No ROP was noted in 888 of the 904 infants examined (98%), 13 infants had stage 1 (1.4%), five infants stage 2 (0.6%) and no infant had stage 3 ROP. No infant developed stage 3 ROP, required treatment for ROP or had threshold disease. CONCLUSION: In this regional study of infants greater than 30 weeks gestation and with a birthweight greater than 1250 g, the prevalence of any ROP was low (2.0%). This study supports evidence from other studies that screening for ROP could be restricted, at least within our referral network, to infants less than 30 completed weeks and a birthweight less than 1250 g.     

Insulin infusions in infants of birthweight less than 1250 g and with glucose intolerance

Fifteen preterm babies (mean gestation: 26.7 weeks; mean birthweight 860 g) with significant glucose intolerance were treated with insulin infusions. During the insulin infusions there was a significant increase in both the mean energy intake (60.8 +/- 25.1 cal/kg per day to 79.9 +/- 24.5 cal/kg per day; P less than 0.001) and the mean amount of intravenous dextrose tolerated (7.0 +/- 2.7 mg/kg per min to 9.2 +/- 2.6 mg/kg per min; P less than 0.01). The infusions were initiated at a mean postnatal age of 5.3 days (range: 2-12 days) and were continued for 1.5-17.5 days. Of the 998 blood glucose estimations performed during the insulin infusions, 28 (2.8%) were less than 2 mmol/l and 216 (21.6%) greater than 8 mmol/l. We conclude that continuous insulin infusion is a safe and effective way of managing glucose intolerance in very low birthweight infants, provided adequate means for continuous monitoring of blood glucose are available.     

Sodium glycerophosphate in the treatment of neonatal hypophosphataemia.

Nineteen very low birthweight (mean (SD) gestational age 28 (3) weeks) were parenterally fed nutrition solutions containing inorganic calcium and phosphorus salts. All infants had hypophosphataemia. Plasma concentrations were maintained between 1.5 mmol/l and 2.2 mmol/l. Plasma phosphorus concentrations reached 1.5 mmol/l or greater in three patients after 12 hours, in a further nine patients after 36 hours, and in all patients by 60 hours. Changes in plasma calcium concentrations were not significant.     

Survival Rate of Extremely Low Birthweight Infants and its Effect on the Amendment of the Eugenic Protection Act in Japan

Because of the increasing survival rate of extremely low birthweight infants in recent years, the viability limit in the Eugenic Protection Act in Japan was amended from 24 to 22 completed weeks of gestation. The Japan Pediatric Society's survey on the outcome of infants born in 1990 focused on infants born before 24 weeks gestation and less than 500 g. The survival rates of infants born in 23, 22 and before 22 weeks gestation overall at 511 hospitals throughout Japan were 43/118 (36%), 3/36 (8%) and 0/8 (0%), respectively. Of 16 infants, none weighing less than 400 g at birth survived but 16 (12%) of 50 infants between 400 and 499 g survived. Up-to-date statistical data is essential to the amendment of the concept of viability and subsequent ethical decision-making on extremely low birthweight infants.     

Plasma osmolality, sodium, and urea in healthy breast-fed and bottle-fed infants in Newcastle upon Tyne.

Dale, G., Goldfinch, M. E., Sibert, J. R., and Webb, J. K. G. (1975). Archives of Disease in childhood, 50, 731. Plasma osmolality, sodium, and urea in healthy breast-fed and bottle-fed infants in Newcastle upon Tyne. Plasma osmolality, sodium, and urea were measured on samples from 50 healthy infants, aged between 18 and 125 days, attending child health clinics in Newcastle upon Tyne. 3 infants had osmolalities greater than 300 mOsm/kg, a lower incidence of hyperosmolality than that previously reported. There was a difference (P less than 0-001) between the plasma urea levels of breast-fed and bottle-fed infants, but not between the osmolalities of these groups. The mean plasma urea of bottle-fed babies was 53 mg/100 ml (SD 12-47), 50-1 mg/100 ml (SD 10-9) if additional solids were being given, and 18-4 mg/100 ml (SD 7-81) for breast-fed babies. There was little difference between the plasma sodium levels of each group. The mean plasma sodium for all groups combined was 135-2 mmol/1 (SD 2-3); no plasma sodium exceeded 140 mmol/1.     

Intraventricular haemorrhage and the renin-angiotensin-aldosterone system in very low birthweight infants

Blood volume, plasma renin activity (PRA) and urine aldosterone excretion (UAE) were measured in ten very low birthweight infants who had a Grade 3 or 4 intraventricular haemorrhage (IVH) during the first 2 days after birth. Mean (range) birthweight was 950 (630-1500) g and gestational age was 27 (23-31) weeks. Nine infants were receiving assisted ventilation and one was breathing spontaneously. Eight IVH occurred on the first postnatal day and two on the second; seven were symptomatic and three asymptomatic. PRA was significantly higher than control values on Day 1 only; median 244 (range 91-654) ng/ml per h vs. 64 (4-259) ng/ml per h (P less than 0.01). Infants with symptomatic IVH in the preceding 8 h (n = 6) all had PRA greater than 300 ng/ml per h; none of these infants had received transfusions or volume expansion between IVH and PRA measurement. PRA was less than 100 ng/ml per h in the three infants with asymptomatic IVH and one infant with greater than 24 h interval between IVH and PRA measurement; three of these four had received transfusions prior to PRA measurement. UAE was not significantly different from control values on either Day 1 or Day 2. Blood volume at 22 +/- 3 h postnatal age ranged from 75 to 107 ml/kg. There was an inverse logarithmic correlation between PRA and blood volume (r = 0.883; P less than 0.005), with PRA values exceeding 300 ng/ml per h when blood volume was less than 90 ml/kg. UAE did not correlate with either PRA or blood volume.(ABSTRACT TRUNCATED AT 250 WORDS)     

Metabolism of potassium in preterm infants]

During the first days of life, hyperkalemia can affect 30 to 60% of very low birth weight infants free of acute renal insufficiency (i.e. nonoliguric hyperkalemia). The place of the kidney in the regulation of the potassium homeostasis of VLBW remains badly specified. OBJECTIVE: To evaluate the rate and the mechanisms of hyperkalemia in infants born at less than 32 weeks' gestation. METHODS: A prospective study was conducted in 33 preterm infants (BW=1289+/-382 g; GA=28.8+/-1.7 weeks). Fifteen consecutive 8-hour urine collections were performed for each infant from the 8th hour of life (495 periods). A plasma sample was obtained at the end of each urine collection. Sodium, potassium and creatinine were measured in urine and blood samples as often as possible. RESULTS: Plasma potassium concentrations varied significantly over the 15 successive periods with an initial value (P1) of 4.55+/-0.80 mmol/l, a peak on P3 (4.94+/-0.81 mmol/l) and the lowest value on P13 (3.88+/-0.42 mmol/l). Hyperkalemia (plasma potassium>6.0 mmol/l) was observed in 4 infants (12%) and in 1.2% of the periods. The cumulative potassium balance (output-input) was negative over the first 7 periods (-1.97 mmol/kg), and afterwards became positive (from P8 to P15:+1.57 mmol/kg). Over the first 3 days, plasma potassium concentrations were positively correlated (p<0.01) with urinary excretion of potassium, clearance of potassium, fractional excretion of potassium, and negatively with endogenous creatinine clearance. CONCLUSION: In the first days of life, very low birth weight infants present an increase in kalemia associated with a negative potassium balance indicating a intracellular to extracellular potassium shift rather than a lower renal potassium excretion.     

Sodium homeostasis in term and preterm neonates. III. Effect of salt supplementation.

Clinical and biochemical effects of supplementing dietary sodium intake to 4 to 5 mmol(mEq)/kg/day from days 4 to 14 of life were studied in 22 infants of gestational age 27 to 34 weeks. These infants were compared with a group of 24 unsupplemented babies. Supplemented infants lost less weight postnatally and regained birthweight more quickly: their improved weight gain continued after supplementation was stopped. Sodium balance was positive at age 5 to 11 days in supplemented babies but slightly negative in controls. Potassium balance was more strongly positive in the supplemented group. Plasma sodium concentration was higher in supplemented infants during weeks 3 and 4. Hyponatraemia was significantly more common in unsupplemented (37.5%) than supplemented (13.6%) infants. No infant became oedematous, hypernatraemic, or showed evidence of circulatory overload. The incidence of patent ductus arteriosus and necrotising enterocolitis was not increased; no intracranial haemorrhages occurred. Urinary potassium:sodium ratio was lower in supplemented babies than controls suggesting responsiveness of the distal tubule to mineralocorticoids. Providing 4 to 5 mmol(mEq)/kg/day of sodium to infants born before 34 weeks'' gestation for the first two postnatal weeks improves growth and biochemical status and causes no undesirable side effects.     

Distribution of plasma vitamin E levels in supplemented very low birthweight infants

The distribution of plasma Vitamin E (VE) was determined in 25 very low birthweight (VLBW) infants who were supplemented with 100 mg/kg per day of alpha-tocopherol acetate, given intragastrically. Their mean birthweight was 917 g and mean gestational age was 28 weeks. Mean plasma VE levels after 1 and 6 weeks' supplementation were 2.7 mg/dL (s.e.m. = 1.0) and 6.4 mg/dL (s.e.m. = 1.4), respectively (the difference was not significant). There was wide variability in plasma VE levels in these infants despite being on an identical dose of tocopherol. Plasma VE was less than 0.5 mg/dL in 12% of samples, 0.5-3.0 mg/dL in 32%, 3.1-5.0 mg/dL in 18%, and 5.1-20 mg/dL in 38%. Fifteen of the 25 infants had at least one level in the range which has been associated with an increased incidence of septicaemia and necrotizing enterocolitis (greater than 5.0 mg/dL). These data suggest that if a policy of VE supplementation for VLBW infants is chosen, monitoring of plasma VE levels appears necessary so that the dosage can be adjusted in order to maintain plasma VE within the optimal range. This study's dosage regimen of supplementing infants with 100 mg/kg per day of VE was associated with a high incidence of elevated plasma VE levels and it is concluded that it is not advisable to use such large doses of VE in the premature newborn.     

The use of Dexamethasone in full-term infants with severe respiratory failure and pulmonary barotrauma

Eight full-term infants (mean gestation 39.9 weeks [range 37-42] and mean birthweight 3642 g [range 3060-4200]) with severe respiratory failure (median oxygenation index 28 [range 16-65] and median arterial/alveolar PO2 ratio (a/APO2) 0.094 [range 0.038-0.165]) and pulmonary barotrauma were treated with Dexamethasone, 0.5 mg/kg per day, from the median age of 5 days (range 3-22). Six of the eight (75%) infants survived. They were weaned from mechanical ventilation and extubated a median of 2.5 days after commencing treatment with Dexamethasone. Two infants died and one of them suffered recurrent pneumothoraces. There was a significant improvement in oxygenation in the seven infants who survived the 72 h period of observation. Their median oxygenation index was 24 when Dexamethasone was commenced compared with 8 after 12 h (P less than 0.05) and 10 after 36 h (P less than 0.025). Their a/APO2 ratio was 0.095 when Dexamethasone was commenced compared with 0.289 after 12 h (P less than 0.05) and 0.207 after 36 h (P less than 0.025). There was a significant increase in the infants' arterial mean blood pressure associated with Dexamethasone therapy and one infant developed Staphylococcus aureus septicaemia. In this uncontrolled study of eight full-term infants with severe respiratory failure and pulmonary barotrauma, the use of Dexamethasone was associated with significant improvement in oxygenation and rapid weaning from mechanical ventilation.     

Chronic lung disease in very low birthweight infants: A prospective population-based study

A prospective population-based study of chronic lung disease among all very low birthweight infants (birthweight 500-1499 g) born in New Zealand in 1986 is reported. Of 413 of these infants admitted to neonatal units, 355 (86%) survived to 28 days. An additional 50 infants were recorded as liveborn but died in the labour ward or other place of birth. Both observed survival and survival adjusted for birthweight, gestation and gender were significantly (P less than 0.05) better in larger centres. Oxygen requirement was assessed at 28 days of age, 36 weeks equivalent gestation and 84 days of age, when 38.6, 23.1 and 13.8% of infants, respectively, were being treated with oxygen. To examine the joint effects of predictor variables on oxygen requirement at each age, the data were analysed using multiple logistic regression methods. At 28 days, lower birthweight, shorter gestation, respiratory distress syndrome (all P less than 0.0001), and gender and hospital principally caring for the infant (both P less than 0.05) were significantly associated with treatment with oxygen. In comparison with other studies, New Zealand appears to have a relatively high rate of chronic lung disease. We speculate that a contributing factor may be the small size of some regional neonatal units.     

Neurosensory outcome and growth at three years in extremely low birthweight infants: follow-up results from the Swedish national prospective study

A prospective national investigation comprising 633 extremely low birthweight (ELBW) infants born alive in the 2-y period 1990-1992 with a birthweight of ≤1000 g and gestational age of ≥23 completed weeks was conducted regarding neurosensory outcome and growth. Three-hundred and sixty-two (98%) surviving ELBW infants were assessed at a median age of 36 months, using a specially designed protocol. At follow-up, mean height, weight and head circumference in both boys and girls were significantly lower than the reference values. The incidence of cerebral palsy was 7% among all children and 14%, 10% and 3% in children born at 23-24, 25-26 and ≥27 gestational weeks, respectively. At least one obvious handicap was present in 14%, 9% and 3% of these three groups of children, respectively. After adjustment for gestational age, a significantly increased risk of handicap was found in children with intraventricular haemorrhage grade ≥3 and/or periventricular leucomalacia and in children with retinopathy of prematurity stage ≥3. The results show that more than 90% of ELBW children born at ≥25 completed gestational weeks were without neurosensory handicap at 36 months of corrected age. In infants born at 23-24 weeks of gestation, both survival and long-term outcome were less favourable.     

New birthweight and head circumference centiles for gestational ages 24 to 42 weeks

Based on 20,713 singleton livebirths at the John Radcliffe Hospital, Oxford, in 1978-1984, we calculated new birthweight and head circumference values for males and females between 24 and 42 weeks of gestation. Among the 803 babies born at or before 34 weeks of gestation, 28% were delivered electively for fetal problems; they were considerably lighter and had smaller heads than infants born after spontaneous preterm labour. As we and others have recommended elsewhere, the electively delivered preterm infants were excluded from the calculation of the new birthweight and head circumference centiles. In our series males were heavier and had larger head circumferences than females at most gestational ages. There were consistent and statistically significant differences in birthweight at all gestational ages from 37 weeks and in head circumference at all gestational ages from 35 weeks.     

Respiratory syncytial virus and premature infants born at 32 weeks' gestation or earlier: hospitalization and economic implications of prophylaxis

OBJECTIVES: To assess the risk of hospitalization associated with respiratory syncytial virus (RSV) and to estimate the economic impact of RSV prophylaxis with either RSV immune globulin (RSV-Ig) or RSV monoclonal antibody (palivizumab) on a cohort of preterm infants born at 32 weeks' gestation or earlier. DESIGN: Historical cohort study. SETTING: A 12-county neonatal network served by the regional center in Rochester, NY. PARTICIPANTS: One thousand twenty-nine infants born at 32 weeks' gestation or earlier followed up until 1 year of corrected age. MAIN OUTCOME MEASURES: Rate of hospitalization with an RSV-associated illness; cost per hospitalization prevented resulting from either form of RSV prophylaxis. RESULTS: The probability of hospitalization with an RSV-associated illness for infants born at 32 weeks' gestation or earlier was estimated at 11.2%. The incidence of RSV hospitalization increased with decreasing gestational age (13.9% vs 4.4% for infants born at < or =26 weeks' gestation vs those born at 30-32 weeks' gestation). Infants requiring respiratory support at 36 weeks of postconceptual age (PCA) or older had a higher hospitalization rate (16.8% vs 6.2%), longer hospital stays, and higher hospital charges than infants requiring respiratory support at less than 36 weeks of PCA. For infants requiring respiratory support at less than 36 weeks of PCA, the incidence of RSV hospitalization still increased with decreasing gestational age (10.2% vs 4.3% for infants < or =26 weeks' gestation vs those 30-32 weeks' gestation). Analysis indicated that both forms of RSV prophylaxis would increase the net cost of care for all groups. Palivizumab was more cost-effective than RSV-Ig for preventing RSV hospitalization among infants who required respiratory support at less than 36 weeks of PCA, especially those born at 26 weeks' gestation or earlier. Overall, RSV-Ig was more cost-effective than palivizumab for infants requiring respiratory support at 36 weeks of PCA or older. CONCLUSIONS: This analysis suggests that available forms of RSV prophylaxis would increase the net cost of care not only for the entire cohort but for each of the subgroups studied. However, the RSV hospitalization rate and the cost-effectiveness of prophylaxis varied markedly by subgroup.     

Necrotizing enterocolitis in a perinatal centre

Thirty-five neonates developed radiologically proven necrotizing enterocolitis (NEC) over a 40 month period. They were 28 +/- 2 weeks gestation, and weighted 1094 +/- 411 g at birth. Eighteen infants (51%) required surgery and three (8.5%) died. The incidence was 6.7% in the very low birthweight (VLBW) infants. A large proportion of NEC (60%) presented beyond 10 days of life. An inverse relationship between gestation and age of onset was observed. The age of presentation was 22 +/- 13 days (range 10-53 days) for the 18 infants less than or equal to 28 weeks compared with 7 +/- 5 days for those over 28 weeks (P less than 0.01). Five NEC infants had bacteraemia which occurred 2-7 days prior to gastrointestinal symptoms of NEC, and four were staphylococcal. Compared with infants controlled for gestation, there was no significant differences observed in perinatal events or feeding history. We concluded that an immature gastrointestinal system is vulnerable to NEC even beyond the early neonatal period.     

Relationship of serum bilirubin levels to ototoxicity and deafness in high-risk low-birth-weight infants

During a 4-year period, 12 premature infants, all less than 34 weeks of gestation and all with a bilirubin level above 240 mumol/L (14 mg/dL) were determined to have bilateral sensorineural deafness. In order to to investigate how far the hyperbilirubinemia or any a associated factor might have been a causative factor, all infants of 34 weeks of gestation or less who had a serum bilirubin level above 240 mumol/L were investigated. For a period of 4 years, 99 infants meeting these criteria were classified as high risk or low risk on the basis of perinatal risk factors. Eight of the 22 high-risk infants with birth weight less than 1,500 g, but only two of 43 high-risk infants with birth weight greater than 1,500 g were deaf (P less than .05). The deaf infants were also matched with infants of normal hearing who had similar bilirubin levels and the same number of adverse perinatal factors. The mean duration of hyperbilirubinemia was significantly longer in the deaf infants (P less than .02), and they appeared to have a greater number of acidotic episodes while they were hyperbilirubinemic. These findings suggest that in healthy preterm infants with birth weight greater than 1,500 g, high bilirubin levels carry little risk, whereas a serum bilirubin level greater than 240 mumol/L in high-risk preterm infants with birth weight of 1,500 g or less is associated with a high risk of deafness.     

Plasma 1.25-dihydroxyvitamin D concentrations in preterm infants

1.25-Dihydroxyvitamin D concentrations were measured in 10 preterm infants (mean gestational age 29 weeks, range 26-32; mean birthweight 1226 g, range 980-1700). Total parenteral nutrition was begun after birth and partial enteral feeding was started at 1 week of age. Total enteral feeding was achieved at a mean age of 26 days (range 16-47). The daily vitamin D3 intake was about 400 I. U. No clinical, chemical or radiological signs of rickets were observed. The mean 1.25-dihydroxyvitamin D concentration +/- SEM was 103.2 +/- 24.0 pmol/l at 1 week (range 9.6-252.0), 141.6 +/- 26.4 at 3 weeks (range 31.2-324.0), 153.6 +/- 21.6 at 6 weeks (range 67.2- 256.8), 165.6 +/- 24.0 at 9 weeks (range 74.4-307.2) and 153.6 +/- 21.6 at 12 weeks (range 76.8-268.8) postnatal age. The mean values at 6, 9 and 12 weeks were significantly higher (p resp. less than 0.01, less than 0.002 and less than 0.005) than in adults (88.8 +/- 7.2; n = 27). 1.25-Dihydroxyvitamin D concentrations were highly variable and did not correlate with 25-hydroxyvitamin D concentrations, plasma calcium and phosphorus concentrations and plasma alkaline phosphatase levels, nor with illness nor postnatal age. The data demonstrate that preterm infants are capable of producing high plasma levels of 1.25-dihydroxyvitamin D.