Nuclear 3,5,3'-triiodothyronine receptors in skeletal muscle of normal and small-for-gestational age newborn piglets

The number of nuclear T3 receptors in the longissimus dorsi muscle has been determined in normal and runt (intrauterine growth-retarded) newborn piglets. Values of maximal binding capacity (Bmax), as calculated by Scatchard analysis, were 48.2 +/- 4.3 and 39.7 +/- 4.7 mol X 10(-14).mg DNA-1 (mean values +/- SEM) for controls and runts respectively (p less than 0.01; n = 13 pairs of littermates). The lower Bmax in the runts may help to explain their reduced metabolic rate and lower respiratory enzyme activities in skeletal muscle, compared with controls of normal birth weight.     

Catch-up growth in appropriate- or small-for-gestational age preterm infants

The aim was to evaluate postnatal growth of preterm infants in childhood and to determine factors that have an effect on catch-up growth (CUG). Ninety-six (42F, 54M) preterm born children with a gestational age of 32.6+/-2.9 weeks and birth weight of 1815+/-668 g were evaluated at age 4.7+/-1.1 years. Preterm children with birth weight and/or length below 10th percentile were accepted as small-for-gestational age (SGA) and those above as appropriate-for-gestational age (AGA). Height SDS was similar (-0.5+/-1.0) in preterm AGA and SGA children. Both groups had low body mass index (BMI) SDS (-0.6+/-1.4 and -1.0+/-1.5, respectively). Of the preterm SGA children, 65.8% showed a CUG in height and 3.8% catch- down growth. These rates were 24.6% and 33.5% in preterm AGA children. CUG in height was best explained by birth length and mother's height and CUG in weight by birth weight and mother's weight. In conclusion, although most of the preterm SGA children show CUG, they reach a compromised height in childhood. A number of preterm AGA children show a catch-down growth.     

Fetal and neonatal mortality of small-for-gestational age infants

Fetal and neonatal mortality of small-for-gestational age (SGA) infants in 1968–1982 were studied in the region of the University Central Hospital of Turku, Finland. During the study period, there were 254 fetal and 127 neonatal deaths in SGA infants. The fetal mortality rate of SGA infants declined from 49.9/1000 to 14.0/1000. The neonatal mortality rate of SGA infants declined from 23.8/1000 to 8.3/1000. The severely SGA infants with a birth weight below the 2.5th percentile had three times higher neonatal mortality rates than SGA infants with a birth weight between the 2.5th and the 10th percentiles. The main causes of fetal deaths were maternal diseases, placental and cord complications and fetal malnutrition, even though there was a decline in all these groups. Malformations remained the main cause of neonatal death during the study period, while there was a decline in deaths due to asphyxia and respiratory distress syndrome (RDS). The high mortality rates of SGA infants emphasize the need for early diagnosis and special attention during pregnancy, delivery and the neonatal period.Abbreviations SGA small-for-gestational age - AGA appropriate-for-gestational age - UCHT University Central Hospital of Turku - RDS respiratory distress syndrome     

Lymphocyte subpopulations in peripheral blood of small-for-gestational age and appropriate-for-gestational age preterm neonates

The lymphocyte subpopulations were investigated in peripheral blood of small-for-gestational age (SGA) and appropriate-for-gestational age (AGA) preterm newborns. In SGA newborns the number and percentage of T lymphocytes were reduced. Among the T lymphocytes, the number and percentage of T helper cells were significantly decreased. The cytotoxic/suppressor T cells were also reduced, but to a lesser extent.     

Serum concentrations of thyroxine-binding globulin, prealbumin and albumin in healthy fullterm, small-for-gestational age and preterm newborn infants.

Simultaneous serum concentrations of thyroxine-binding globulin (TBG), prealbumin (TBPA) and albumin (Alb) were measured in 130 fullterm, 32 small-for-gestational age and 25 preterm infants during their first six days of life. In all infants serum concentrations of TBG were higher and serum TBPA and Alb were lower than in male adults. Even higher serum TBG levels were found in the mothers. There was no correlation between serum concentrations in paired maternal and cord sera. In infants with birth weights appropriate for gestation serum TBG, TBPA, and Alb concentrations increased progressively with gestational age. In small-for-gestational age infants born at term serum concentrations of TBG and Alb were lower than those in fullterm, but higher than those in premature newborns. Serum TBPA in small-for-gestational age babies was even lower than seen in prematures. A positive correlation was found between thyroid hormones and TBG concentrations, not between serum TBPA and thyroid hormones. The ratios between serum concentration of thyroid hormones and proteins might indicate that more thyroid hormonebinding sites are occupied in fullterm than in low birth-weight newborns. However, the main reason for the different serum levels of thyroid hormones in fullterm, small-for-gestational age and preterm babies is probably the various serum TBG concentrations demonstrated in these infants.     

Maternal age and other predictors of newborn blood pressure

OBJECTIVE: To investigate perinatal predictors of newborn blood pressure. STUDY DESIGN: Among 1059 mothers and their newborn infants participating in Project Viva, a US cohort study of pregnant women and their offspring, we obtained five systolic blood pressure readings on a single occasion in the first few days of life. Using multivariate linear regression models, we examined the extent to which maternal age and other pre- and perinatal factors predicted newborn blood pressure level. RESULTS: Mean (SD) maternal age was 32.0 (5.2) years, and mean (SD) newborn systolic blood pressure was 72.6 (9.0) mm Hg. A multivariate model showed that for each 5-year increase in maternal age, newborn systolic blood pressure was 0.8 mm Hg higher (95% CI, 0.2, 1.4). In addition to maternal age, independent predictors of newborn blood pressure included maternal third trimester blood pressure (0.9 mm Hg [95% CI, 0.2, 1.6] for each increment in maternal blood pressure); infant age at which we measured blood pressure (2.4 mm Hg [95% CI 1.7, 3.0] for each additional day of life); and birth weight (2.9 mm Hg [95% CI, 1.6, 4.2] per kg). CONCLUSIONS: Higher maternal age, maternal blood pressure, and birth weight were associated with higher newborn systolic blood pressure. Whereas blood pressure later in childhood predicts adult hypertension and its consequences, newborn blood pressure may represent different phenomena, such as pre- and perinatal influences on cardiac structure and function.     

Growth and development of term disproportionate small-for-gestational age infants at the age of 7 years

Twenty-four term infants with disproportionate intrauterine growth retardation (SGA group) and 24 normally grown term infants matched for age, sex, birth rank and social class were followed from birth until 7 years of age. Both groups were free from perinatal complications and chronic diseases. The children in the SGA group continued to be underweight-for-height with a low ponderal index and a relatively small head circumference at the age of 7 years. Only minor shifts occurred in the individual growth curves since the age of 3 years. In 12 SGA children and 1 control multiple 'soft' neurological signs were found. Their grammar school teachers observed problematic behavior (hyperactivity, poor concentration and clumsiness) in 9 and academic problems in 5 of the 12 SGA children with neurological dysfunction. These findings indicate that disproportionate intrauterine growth retardation at term can have long-term effects on growth and development.     

Serum IgG at birth in preterm appropriate- and small-for-gestational age newborns

Serum IgG at birth was estimated in 31 preterm and 33 full term newborns, grouped according to their weight-for-gestational age. Preterm small-for-gestational age neonates were found to have significantly reduced IgG levels as compared to preterm appropriate-for-gestational age and full term small-for-gestational age newborns. It is suggested that preterms with intra-uterine growth retardation are most suitable for exogenous IgG supplementation to reduce neonatal and postneonatal susceptibility to infections.     

Neurological development of small-for-gestational age babies during the first year of life

137 small-for-gestational age (SGA) infants were examined in the neonatal period and at 2, 6 and 12 months. At each age a structured assessment was used for which a score denoting neurological maturation could be given. The SGA infants were significantly retarded compared with average-for-gestational age (AGA) infants from 2 months onwards. Within the SGA group the mean scores for boys, those who were first-born, breast-fed and/or born to mothers who smoked during pregnancy were in each case significantly higher than the rest at 6 and 12 months. Maternal smoking influenced all aspects of development at 12 months; whereas sex and method of infant feeding mainly affected the motor items, and birth order only those that were socially oriented. Positive associations were found between changes in somatic measures and changes in neurological scores from birth through to 6 months. Infants who grew faster also matured faster during this period of time, and vice versa. Positive correlations were found between size and scores at 2 and 6 months, but not at 12 months.     

Blood pressure and tissue oxygenation in the newborn baby at risk of brain damage

A cardinal aim of neonatal intensive care is the maintenance of an adequate oxygen supply to the tissues, particularly the brain. This process depends on several factors. These include an adequate blood oxygen content, blood flow to the tissues and the ability of cells to extract and utilise oxygen. Oxygen carriage depends on ventilation and haemoglobin concentration and type. Blood flow depends on cardiac output (in turn dependent on cardiac contractility, heart rate, blood pressure and vascular resistance). Different tissues also have different oxygen demands depending on their oxygen consumption, which are likely to vary within the tissue itself and with the activity of the infant. This paper discusses evidence that suggests that even in preterm neonates, cerebral blood flow may be independent of blood pressure, and that even very low cerebral blood flow seems to be consistent with healthy survival. Evidence is considered that cardiac output rather than blood pressure may be more important in determining brain tissue oxygenation. We have found a negative correlation between cardiac output and cerebral oxygen extraction in preterm infants, but no relationship between mean arterial blood pressure and cerebral oxygen extraction.     

Pituitary-thyroid responsiveness to thyrotropin-releasing hormone in preterm and small-for-gestational age newborns.

A dose of 40 microgram TRH was injected intravenously in 12 preterm (PT) and 15 small-for-gestational age (SGA) babies (with advanced gestational ages) between 5 and 167 hours after birth. Serum-thyrotropin (TSH) was measured prior to and 30 and 180 min after TRH; serum-thyroxine (T4) and serum-triiodothyronine (T3) were measured prior to and 180 min after TRH. The percentage increase in serum-TSH in PT and SGA babies was comparable to that of fullterm newborns. The serum-TSH 30 min after TRH in SGA newborns was significantly correlated to basal TSH values, such a correlation could not be shown in the preterms. One SGA and four PT babies had a repeat TRH-test performed later in infancy: In all but one PT with a gestational age of 27 weeks the TSH rise was lower than in the neonatal period. The thyroid hormone responses after TRH were similar in the two groups of babies. The percentage increase above basal levels were: Median serum-T3 increase about 46% and median serum-T4 increase about 14%. It is concluded that in low-birth-weight newborn babies the pituitary TSH response to exogenous TRH was like that detected in fullterm newborns and more pronounced that later in infancy. The effect of endogenous TSH as measured by thyroid hormone increases was of the same magnitude as observed in fullterms and in adults.     

Blood transfusion in newborn

Premature infants are among the most frequently transfused groups of patients, usually receiving red cells. The immaturity of the immune system, its lesser ability to cope with a metabolic load and the presence of maternal antibodies, all complicate the picture. Conservation of blood to minimize losses and the need for replacement transfusion is an important strategy that has already been successful in reducing the need for transfusion on neonatal units. The advent of erythropoietin provides another strategy for reducing the need for transfusion. It is unfortunate that the sickest patients who require the most transfusion poorly respond to erythropoietin. Main concern is the long-term consequences of transfusion. Presently the aim is to minimize transfusion risks and give transfusions only when they are indicated.