Effects of extremely early enteral feeding on plasma glicentin levels in very-low-birthweight infants

AIM: Glicentin, an active component of enteroglucagon, is considered to have a significant trophic action on the intestinal mucosa. We examined the effects of extremely early enteral feedings on the postnatal and postprandial changes in plasma glicentin levels in very-low-birthweight (VLBW) infants. METHODS: We measured the plasma glicentin concentrations before and after feedings at 1 or 2 days, 5 or 6 days and 14 days after birth in 21 VLBW infants. The subjects were randomly divided into an extremely early feeding group, which was started on breast milk within 24 h after birth, and a control group, which was started on breast milk more than 24 h after birth. RESULTS: Plasma basal concentrations of glicentin at 5 or 6 days and at 14 days after birth were significantly higher than those at 1 or 2 days after birth in the early feeding group. The basal glicentin level at 14 days after birth was significantly higher than that at 1 or 2 days. The basal levels at 5 or 6 days and at 14 days after birth in the early feeding group were significantly higher than those in the control group. Plasma glicentin concentrations after feeding were significantly higher than those before feeding at 5 or 6 days and 14 days after birth in the early feeding group, but those levels were significantly higher only at 14 days after birth in the control group. CONCLUSION: Our results suggest that extremely early enteral feedings may play an important role in the development of glicentin secretion and intestinal mucosal growth in the early period of life in VLBW infants.     

Effects of intralipid infusion on blood viscosity and other haemorheological parameters in neonates and children

Aim: To study acute haemorheological effects of intralipid in preterm and full-term neonates and children. Circulatory complications of intralipid infusion, such as increases in pulmonary and peripheral flow resistance, have been associated with impaired blood rheology. Methods: During total parenteral nutrition, 10 preterm infants, 10 full-term neonates and 10 children received an initial dose of intralipid as continuous infusion (0.6 g/kg) over 4 h. Additionally, blood of 10 healthy preterm infants, 10 full-term neonates and 10 adults was incubated with intralipid. Whole blood and plasma viscosity (capillary viscometer), red blood cell (RBC) deformability (rheoscope) and RBC aggregation (Myrenne aggregometer) were measured before and after intralipid infusion and before and after in vitro incubation of blood with intralipid. Results: During intralipid infusion, plasma triglyceride levels increased from 0.13 ± 0.27 to 2.16 ± 0.68 g/l in the preterm infants, from 0.14 ± 0.21 to 1.64 ± 0.54 g/l in the full-term neonates and from 0.65 ± 0.31 to 2.26 ± 0.60 g/l in the children. Whole blood viscosity decreased by about 10% after intralipid in all three groups due to similar decreases in haematocrit. RBC aggregation decreased by about 20% after intralipid infusion. Plasma proteins, plasma viscosity and RBC deformation were not affected by intralipid. In vitro incubation of blood with intralipid resulted in a marked reduction of RBC aggregation that was related to the intralipid concentration. At intralipid concentrations of 4 and 8 mg/ml, no RBC aggregation was noted in preterm and full-term neonates. In adults, RBC aggregation decreased by 50%.

Conclusions: Previously described deleterious effects of intralipid on circulation can not be explained by changes in haemorheological properties.     

Mother-infant skin-to-skin contact after delivery results in early recognition of own mother's milk odour

Aim: To determine the effects of mother-infant skin-to-skin contact immediately after birth on infant recognition of their own mother's milk odour and breastfeeding duration until 1 y of age. Methods: Sixty healthy, full-term neonates were randomly assigned to group A with skin-to-skin contact and group B without. One and 4 d after birth, infant responses to the following odour stimuli were observed: own mother's milk, another mother's milk, formula, orange juice and distilled water. Infant facial action was videotaped and the frequency of mouthing movements was evaluated for each stimulus. Nutritional assessment, focused particularly on breastfeeding, was performed every 3 mo on participating infants. Statistical analysis comparing the frequency of mouthing movements with the aforementioned five different odour exposures was performed by ANOVA with Fisher's PLSD. Kaplan-Meier analysis with a log-rank test was used to compare breastfeeding rates between groups. Results: Infants in both groups responded differently to mother's milk odour (either their own or another mother's milk) compared to the other stimuli on days 1 and 4. However, infants in group A demonstrated a larger difference in mouthing movements between their own and another mother's milk odour at 4 d of age (2.6 ± 1.6) compared to infants in group B (0.9 ± 2.0, p = 0.01). Infants in group A were breastfed an average of 1.9 mo longer than the others.

Conclusion: Our study provides evidence that mother-infant skin-to-skin contact for more than 50 min immediately after birth results in enhanced infant recognition of their own mother's milk odour and longer breastfeeding duration.     

PCDDs, PCdfs and Co-PCBs in human breast milk samples collected in Tokyo, Japan

Aim: To observe the distribution of PCDD/Fs and Co-PCBs in samples of human breast milk collected in Japan. Methods: Using high-resolution gas chromatography, milk samples for polychlorinated dibenzo-p-dioxins (PCDDs; 14 congeners), polychlorinated dibenzofurans (PCDFs; 15 congeners) and coplanar polychlorinated biphenyls (Co-PCBs; 12 congeners) from 240 mothers residing in Tokyo were analysed. There were 120 donors each of primiparae and secundiparae, each group including 60 donors aged 25 to 29 y (“the younger group”) and 60 aged 30 to 34 y (“the older group”). Individual milk samples (about 50 ml) were obtained 30 d after delivery in 1999 and in 2000. Results: The mean toxic equivalent (TEQ) level of PCDD/Fs (the sum of PCDDs and PCDFs) was 14.9 pg TEQ/g fat, of Co-PCBs 10.6 pg TEQ/g fat, and the total sum of PCDD/Fs and Co-PCBs was 25.6 pg TEQ/g fat. The mean TEQ levels of PCDD/Fs, Co-PCBs, and total PCDD/Fs and Co-PCBs were higher in primiparae than in secundiparae. In each of these, the levels were higher in the subgroup of older mothers. In the secundiparae, the mean levels were lower in the group of mothers who had breastfed their first babies than in those who bottle-fed or partly bottle-fed their first born.

Conclusions: The concentrations of PCDD/Fs and Co-PCBs in the breast milk of Japanese women were slightly lower than those described in previous studies conducted in Japan and other countries; and the concentrations of PCDD/Fs and Co-PCBs in the breast milk were influenced mainly by the mother's age and nursing history.     

Effect of tilting on cerebral haemodynamics in preterm infants with periventricular leucencephalomalacia

Aim: Measurement of cerebral haemodynamics to detect impaired cerebral blood flow and impaired cerebral autoregulation might make prevention of brain lesions and especially periventricular leucencephalomalacia (PVL) achievable. Methods: Changes in cerebral blood volume (CBV) and the cerebral haemoglobin oxygenation index (cHbD) following tilting up and down in 10 preterm infants with PVL and 25 preterm infants without PVL, measured by near infrared spectroscopy (NIRS), were analysed. Tilting manoeuvres were recorded with a polysomnographic system in combination with NIRS. CBV and cHbD of the baseline phase (1 min before tilting) were compared with data from the post-tilting phase (1 min after tilting). Results: Changes in CBV and cHbD after tilting were significantly pronounced in infants with PVL compared with infants without PVL. CBV decreased in infants with PVL, by -0.099 ± 0.081 ml 100 g ^-1 brain (mean ± SD) after tilting up, and increased by 0.106 ± 0.104 ml 100 g ^-1 brain after tilting down. CBV decreased in infants without PVL, by -0.041 ± 0.068 ml 100 g ^-1 brain after tilting up, and increased by 0.020 ± 0.096 ml 100 g ^-1 brain after tilting down. cHbD showed similar changes after tilting.

Conclusion: Changes in CBV and cHbD after tilting were pronounced in preterm infants with PVL and this may indicate reduced cerebral autoregulatory capacity.     

Concentration of Twelve Plasma Proteins at Birth in Very Low Birthweight and in Term Infants

ABSTRACT. Plasma samples obtained at birth from 70 very low birth weight (VLBW) infants (gestational age 24 to 34 weeks) and from 20 term infants were analysed for concentrations of 12 different proteins. The plasma concentrations of albumin, transthyretin (TTR), retinol-binding protein (RBP), vitamin D-binding protein, apolipoprotein A I, fibronectin, orosomucoid and α₁-antichymotrypsin were significantly lower in the VLBW infants than in the term infants, whereas the values of α-fetoprotein (AFP) were significantly higher in the VLBW infants. No differences were found between the two groups for apolipoprotein A II, apolipoprotein B and transferrin. Birth asphyxia and sex had no influence on the measured plasma protein concentrations. The plasma concentrations of apolipoprotein A I and A II were significantly lower in small-forgestational age (SGA), VLBW infants compared with appropriate-for-gestational age (AGA), VLBW infants. Possible acute inflammation (defined as raised concentrations of orosomucoid or α₁-antichymotrypsin) was associated with significantly higher values of vitamin D-binding protein in both VLBW and term infants, suggesting that this protein may act as an acute phase protein in newborn infants.     

Ghrelin and motilin concentration in colicky infants

Aim: To evaluate serum ghrelin and motilin concentration in infants with infantile colic. Methods: A case-control study was conducted on fasting blood venous samples obtained from 18 infants with infantile colic and 20 healthy infants to measure ghrelin (RIA test) and motilin (RIA test). Results: Colicky infants showed higher ghrelin serum levels (2534.2±600.0 pg/ml; ln 7.8±0.2) than controls (2126.1±281.3 pg/ml; ln 7.6±0.1) (p = 0.011). Serum motilin concentration was significantly higher in colicky infants (94.6±23.2 pmol/l) than in controls (64.1±30.1 pmol/l) (p=0.001). Motilin concentrations were higher in formula-fed colicky infants (104.5±20.4 pmol/l) than in breastfed ones (82.2±21.3 pmol/l) (p = 0.038).

Conclusion: Our finding shows that ghrelin and motilin concentrations are higher in infants with colic than in controls, supporting an organicistic aetiopathogenesis of this disorder. Furthermore, the role of ghrelin on gastrointestinal motility may open new doors to better understand the aetiology of infantile colic.     

Whole blood interleukin 8 and plasma interleukin 8 levels in newborn infants with suspected bacterial infection

Aim: To evaluate a new micro-method technique for measurement of interleukin 8 in detergent-lysed whole blood (whole blood IL-8) applicable to capillary blood sampling as a test for bacterial infections in neonates. Methods: Whole blood IL-8 was measured at the first suspicion of infection along with IL-8 determined in plasma (plasma IL-8), C-reactive protein and blood cultures in 154 consecutive newborn infants with clinical signs of bacterial infection. Only 20 μl of whole blood were required for the new assay. Results: Blood culture-proven infections were diagnosed in six infants and clinical infection (defined as a combination of clinical and laboratory signs) in 20 infants. 1000 pg/ml was determined as the suitable threshold for whole blood IL-8 by ROC-curve analysis. At that threshold, whole blood IL-8 detected blood culture-proven infections with a sensitivity of 83% and a specificity of 67%. The areas under the ROC curves were similar for whole blood IL-8 and plasma IL-8.

Conclusions: Compared with plasma IL-8, whole blood IL-8 offers the advantages that measurements of whole blood IL-8 require a smaller blood sample volume and are not altered by haemolysis. The diagnostic accuracy of whole blood IL-8 remains to be studied in more detail in the future.     

Does the choice of bottle nipple affect the oral feeding performance of very‐low‐birthweight (VLBW) infants?

Background: There is a continuous debate regarding the best bottle nipple to be used to enhance the bottle-feeding performance of a preterm infant. Aim: To verify that feeding performance can be improved by using the bottle nipple with the physical characteristics that enhance infants' sucking skills. Methods: Ten “healthy” VLBW infants (941±273 g) were recruited. Feeding performance was monitored at two time periods, when taking 1-2 and 6-8 oral feedings/d. At each time and within 24 h, performance was monitored using three different bottle nipples offered in a randomized order. Rate of milk transfer (ml/min) was the primary outcome measure. The sucking skills monitored comprised stage of sucking, suction amplitude, and duration of the generated negative intraoral suction pressure. Results: At both times, infants demonstrated a similar rate of milk transfer among all three nipples. However, the stage of sucking, suction amplitude, and duration of the generated suction were significantly different between nipples at 1-2, but not 6-8 oral feedings/d.

Conclusion: We did not identify a particular bottle nipple that enhanced bottle feeding in healthy VLBW infants. Based on the notion that afferent sensory feedback may allow infants to adapt to changing conditions, we speculate that infants can modify their sucking skills in order to maintain a rate of milk transfer that is appropriate with the level of suck-swallow-breathe coordination achieved at a particular time. Therefore, it is proposed that caretakers should be more concerned over monitoring the coordination of suck-swallow-breathe than over the selection of bottle nipples.     

Selective improvement in cognitive test scores of extremely low birthweight infants aged between 2 and 5 years

Abstract The cognitive development at 2 and 5 years of a cohort of extremely low birthweight (ELBW) children (birthweight 500-999 g) was compared with that of cohorts of larger very low birthweight (VLBW) children (birthweight 1000-1500 g) and normal birthweight (NBW) children (birthweight > 2500 g) to determine whether the improvements in cognitive function of ELBW infants between 2 and 5 years are apparent or real.
At 2 years of age, ELBW children had a mean Mental Developmental Index (MDI) on the Bayley Scales of 90.4, significantly lower than the means of 100.3 for the larger VLBW children ( P = 0.006), and 107.8 for the NBW children ( P = 0.0002). However by 5 years the mean scores on the Wechsler Preschool and Primary Scales of Intelligence (WPPSI) full-scale for the ELBW and larger VLBW children were virtually identical (105.9 and 106.0 respectively)—but still lower than the mean WPPSI full-scale of 114.6 for the NBW children. After standardizing the MDI and WPPSI scores relative to the NBW children, the ELBW children improved between 2 and 5 years (paired t -test, t = 3.2, P = 0.004) whereas the larger VLBW infants did not.
We postulate that ELBW children require more time than larger VLBW children after birth to compensate for perinatal and other stresses, and that developmental delay at 2 years may not always persist to 5 years.     

Effects of short-term dexamethasone treatment on collagen synthesis and degradation markers in preterm infants with developing lung disease

Aim: To assess the effects of dexamethasone treatment on collagen turnover in preterm infants. Methods: The serum concentrations of the amino-terminal propeptide of type I and III procollagens (PINP and PIIINP), which reflect rates of type I and III collagen synthesis, respectively, and the carboxy-terminal telopeptide of type I procollagen (ICTP), which reflects the rate of type I collagen degradation, were monitored in 13 preterm infants receiving dexamethasone and 13 matched control infants without glucocorticoid treatment for a total period of 12 mo. Dexamethasone was started at a median age of 12 d and continued at tapering doses for a median total duration of 10 d. Blood samples were taken immediately after birth, at 7, 14 and 28 d of age and at 2, 3, 6, 9 and 12 mo. The same markers were also measured just before the initiation of dexamethasone and on days 1, 3, and 7 of treatment. Results: A striking decrease in all of the markers was already observed in every case on day 1 of dexamethasone, the suppression being greatest on day 3 and still considerable on day 7. The percentages from the pretreatment levels recorded on days 1, 3 and 7 were: for PINP 51, 26 and 45%; for PIIINP 63, 44% and 52%; and for ICTP 64, 41 and 51%. A rebound rise in PINP levels was seen in dexamethasone-treated infants, the levels exceeding those of the controls at 3 and 6 mo of age. A similar phenomenon was noted concerning PIIINP at 3 mo. The levels settled down at 9 and 12 mo.

Conclusion: Dexamethasone causes an immediate, inevitable, deep suppression of type I and III collagen synthesis and also type I collagen degradation. This should be taken into consideration, e.g. when assessing for the indications for steroid treatment in sick preterm infants and its dosing and duration.     

Plasma nitrite/nitrate and endothelin-1 concentrations in neonatal sepsis

Aim: To determine the changes in plasma nitrite/nitrate (NOx) and endothelin-1 (ET-1) concentrations during neonatal sepsis. Methods: In a prospective study, 60 consecutive newborns meeting the criteria for sepsis and without receiving exogenous nitric oxide (25 haemoculture-positive [HC+] and 35 haemoculture-negative [HC-]) were compared with 68 healthy newborns (46 full-term and 22 preterm). NOx and ET-1 concentrations were measured in each newborn within 48 h of diagnosis of sepsis and then every third day up to three determinations. SNAP-II and SNAPPE-II severity scores were performed at the moment of highest clinical severity. Results: At the beginning of the sepsis period, controls and septicaemic newborns had similar NOx and ET-1 levels, with the exception of infants with severe HC+ sepsis. Throughout the sepsis period, NOx increased in moderate HC+ sepsis and decreased in HC- sepsis, reaching a significant difference at the end of the study period (59.9 ± 72.7 vs 33.9 ± 15.3 μmol/L; p = 0.036). Meanwhile, ET-1 in newborns with severe HC+ sepsis remained higher than that in the moderate HC+ sepsis group and HC- group, reaching significant differences in all the periods. The highest ET-1 value was positively correlated with SNAP-II and SNAPPE-II scores.

Conclusion: NOx concentrations increased throughout the neonatal HC+ sepsis period, reaching significant differences after 7-9 d. The highest ET-1 levels in neonatal HC+ sepsis emerged before the NOx peak, at 3-5 d, and later decreased. Only newborns with severe HC+ sepsis presented a significant increase in ET-1 concentrations from the beginning of the septicaemic process.     

Randomized study of nasal continuous positive airway pressure in the preterm infant with respiratory distress syndrome

Aim: To evaluate whether very preterm babies can be extubated successfully to nasal continuous positive airway pressure (nCPAP) within one hour of birth after receiving one dose of surfactant in the treatment of respiratory distress syndrome (RDS). Methods: Forty-two infants of 25 to 28[Formula: See Text] wk of gestation were intubated at birth and given one dose of surfactant. They were then randomized within one hour of birth to either continue with conventional ventilation or to be extubated to nCPAP. Results: Eight out of 21 (38%) babies randomized to nCPAP did not require subsequent reventilation. (Ventilation rates of 62% vs 100%, p = 0.0034). The smallest baby successfully extubated weighed 745 g. There were also significantly fewer infants intubated in the nCPAP group at 72 h of age (47% vs 81%, p = 0.025). There was no significant difference between the two groups in the number of babies that died, developed chronic lung disease or severe intraventricular haemorrhage.

Conclusion: A significant number of very preterm babies with RDS can be extubated to nCPAP after receiving one dose of surfactant. nCPAP is a potentially useful modality of respiratory support even in very premature infants.     

Selective improvement in cognitive test scores of extremely low birthweight infants aged between 2 and 5 years

The cognitive development at 2 and 5 years of a cohort of extremely low birthweight (ELBW) children (birthweight 500-999 g) was compared with that of cohorts of larger very low birthweight (VLBW) children (birthweight 1000-1500 g) and normal birthweight (NBW) children (birthweight greater than 2500 g) to determine whether the improvements in cognitive function of ELBW infants between 2 and 5 years are apparent or real. At 2 years of age, ELBW children had a mean Mental Developmental Index (MDI) on the Bayley Scales of 90.4, significantly lower than the means of 100.3 for the larger VLBW children (P = 0.006), and 107.8 for the NBW children (P = 0.0002). However by 5 years the mean scores on the Wechsler Preschool and Primary Scales of Intelligence (WPPSI) full-scale for the ELBW and larger VLBW children were virtually identical (105.9 and 106.0 respectively)--but still lower than the mean WPPSI full-scale of 114.6 for the NBW children. After standardizing the MDI and WPPSI scores relative to the NBW children, the ELBW children improved between 2 and 5 years (paired t-test, t = 3.2, P = 0.004) whereas the larger VLBW infants did not. We postulate that ELBW children require more time than larger VLBW children after birth to compensate for perinatal and other stresses, and that developmental delay at 2 years may not always persist to 5 years.     

Recovery of metabolic acidosis in term infants with postasphyxial hypoxic-ischemic encephalopathy

Aims: To describe the base deficit (BD) values and the rate of postnatal recovery of the BD of infants with hypoxic ischemic encephalopathy due to intrapartum asphyxia; and to explore the relationships between the rate of recovery of BD, severe adverse outcome and different time patterns (acute total vs prolonged partial) of asphyxia. Methods: Clinical and laboratory data were collected from the neonatal period (n = 244) and outcome data to a minimal age of 1 y (n = 218). Rates of recovery of BD were described in four 60 min blocks of time. The values of rate of recovery were compared between the outcome groups, ignoring correlation structure within subjects and with adjustment by the generalized estimating equations method. Results: The BD normalized within 4 h of birth in all but 9 of 244 infants. The rates of recovery of BD in infants with good and severe adverse outcome respectively were 0.11 [95% confidence interval (95% CI) 0.07, 0.14] and 0.09 (95% CI 0.07, 0.12) mmol l ^-1 min ^-1 over the first 4 h after birth. The rates of recovery were similar with or without buffer therapy, and after acute near-total and prolonged partial asphyxia.

Conclusion: The BD in the great majority of infants with severe intrapartum asphyxia normalizes within 4 h of birth. The BD recovery rate of infants with adverse outcomes was similar to those with relatively good outcome. The different time patterns of asphyxial episode were not associated with differential recovery profiles.     

Hypercontractile heart failure caused by catecholamine therapy in premature neonates

Catecholamine treatment for hypotension is common practice in neonatal intensive care units. In the presence of left ventricular hypertrophy, the positive inotropic action of catecholamines with mainly β-receptor specificity can lead to excessive hypercontractility and paradoxical hypotension. This reports presents two cases of hypercontractile heart failure during β-agonist treatment in very low birthweight (VLBW) infants. Both patients (27 wk, 5 d; and 26 wk, 6 d of gestation) underwent surgical arterial duct ligation and coarctation repair. After operation they developed arterial hypotension that failed to respond to epinephrine (adrenaline) or dobutamine treatment. Echocardiography demonstrated a complete systolic obliteration of the left ventricular cavity. Epinephrine and dobutamine were stopped, and norepinephrine (noradrenaline) was successfully used to control the hypotension.

Conclusion: Treatment of hypotension with β-agonists in VLBW infants with left ventricular hypertrophy can lead to hypercontractility and left ventricular obliteration with paradoxical hypotension. Careful echocardiographic monitoring is indicated in such cases.     

Very low birth weight and growth into adolescence

OBJECTIVE: To compare the growth and pubertal development of very low-birth-weight (VLBW) children (birth weight <1500 g) and normal-birth-weight (NBW) children (birth weight >2499 g) to adolescence to determine if, and at what age, VLBW children "catch up." DESIGN: Inception cohort study to age 14 years. SETTING: Royal Women's Hospital, Melbourne, Australia. PATIENTS: Eighty-six consecutive survivors with a birth weight less than 1000 g, 120 consecutive survivors with a birth weight of 1000 to 1499 g, and 60 randomly selected NBW controls. Children with cerebral palsy at age 14 years were excluded. MAIN OUTCOME MEASURES: Weight, height, and head circumference measurements at birth and ages 2, 5, 8, and 14 years converted to z (SD) scores. RESULTS: At age 14 years, pubertal development was similar in NBW and VLBW children. At ages 2, 5, 8, and 14 years, VLBW children were significantly shorter and lighter and had smaller head circumferences than NBW children. The differences in height and weight between VLBW and NBW children were less apparent as SD scores improved in VLBW children over time. Within the VLBW group, compared with children with a birth weight of 1000 to 1499 g, those with a birth weight less than 1000 g had significantly lower weight z scores earlier in childhood but not at age 14 years, significantly lower height z scores only at age 2 years, and significantly lower head circumference z scores throughout childhood. CONCLUSION: This group of VLBW children experienced late catch-up growth to age 14 years but remain smaller than their NBW peers. Arch Pediatr Adolesc Med. 2000;154:778-784     

Cognition, academic progress, behavior and self-concept at 14 years of very low birth weight children

The aim of this study was to compare cognition, academic progress, behavior, and self-concept children of very low birth weight (VLBW, birth weight < 1501 g) born in the period 1980 to 1982 with randomly selected children of normal birth weight (NBW, birth weight > 2,499 g). At 14 years of age, 130 (84.4%) of 154 VLBW and 42 (70.0%) of 60 NBW children were assessed. Ten VLBW children and one NBW child who had cerebral palsy were excluded. VLBW children scored at a significantly lower level on all three composite scales of the Wechsler Intelligence Scale for Children, 3rd Edition. VLBW children were also significantly disadvantaged on more specific cognitive processes, including tests of visual processing and visual memory and on subtests reflecting learning and problem solving. Only in arithmetic was a difference between the groups discerned on tests of achievement. Significantly more VLBW children were rated by teachers as socially rejected and by their parents as having learning problems at school. VLBW children had significantly reduced self-esteem. VLBW children had more cognitive, academic, and behavioral problems and lower self-esteem at 14 years of age than NBW control subjects.     

Difference in plasma bilirubin concentration between monozygotic and dizygotic newborn twins

Aim: To investigate whether inherited factors, other than those already known, influence the bilirubin concentration in neonates of northern European descent, by comparison of monozygotic and dizygotic twins with respect to differences in the plasma bilirubin concentrations between the twins. Methods: 77 healthy pairs of twins of the same gender with a gestational age ≥250 d and of northern European descent were included. Fourth postnatal day blood sampling was done. A multiple linear regression analysis was carried out with the difference in serum bilirubin concentration between the twins as the independent factor, and zygosity, gender, gestational age, postnatal age, maternal smoking, ABO blood-type incompatibility, and the differences between the twins in blood haemoglobin concentration, formula feeding and weight loss as dependent factors. Results: 27 pairs of twins were monozygotic and 50 pairs dizygotic. The analysis showed that the difference in serum bilirubin concentration between the twins was dependent on whether the twins were monozygotic or dizygotic, i.e. the estimated difference in serum bilirubin concentration between the monozygotic twins was 17.8 μmol l^-1 [SE 6.6 μmol l^-1, p = 0.02, 95% confidence interval (95% CI) 3.4, 32.3 μmol l^-1] less than the difference between the dizygotic twins, adjusted for the above-mentioned potential confounders. The difference in serum bilirubin concentration between the twins was positively correlated to the difference in weight loss (%) between the twins (adjusted estimate 5.2 μmol l^-1, SE 2.1 μmol l^-1, p = 0.01, 95% CI 1.2, 9.3 μmol l^-1).

Conclusion: In a population of northern European descent, other genetic factors than gender and ABO blood type were significant for the plasma bilirubin concentration in healthy infants.