Serum netilmicin levels in premature AGA infants

Safe use of aminoglycosides requires close monitoring of serum concentrations. Limited information coupled with marked changes in fluid compartments and renal function during the first week of life in premature neonates makes interpretation of peak and trough levels very difficult. This study was designed to measure serum netilmicin levels following a 2.5 mg/kg IV push infusion. Blood samples were taken on the 5th day of therapy 1 hour before and 1, 6, and 11 hours after a dose. Fifteen premature infants weighing 1000-1500 gm at birth and 20 others whose weight ranged from 1501-2750 gm comprised the study population. All premature infants were appropriate for gestational age (AGA) and of them, only two were severely asphyxiated. At the time of the study, 10 neonates were still on respirators. Serum and urine sodium and creatinine, BUN, and urinalysis were obtained in 28 of these infants. No evidence of renal dysfunction was found. All infants received 100 mg/kg IV ampicillin every 12 hours, but none were being treated with diuretics. Serum netilmicin levels were measured by an enzymatic immunoassay, peak and trough were calculated by extrapolating the first order decay curve. Peak levels ranged from 3.4 to 14 micrograms/ml (means 6.1 +/- 2.5 micrograms/ml SD) and 90% of them were above 4 micrograms/ml. Half of the small premature infants (1000-1500 gm birthweight) presented trough values above 3 micrograms/ml. Pharmacokinetic analysis of our data predicts that a 2.5 mg/kg loading dose followed by 2 mg/kg given every 12 hours will decrease by one-half the number of small prematures exceeding the considered "safe" trough level (greater than 3 micrograms/ml).     

Gentamicin dosage recommendations for neonates based on half-life predictions from birthweight

The appropriate dosing of gentamicin in the newborn was evaluated. Gentamicin was administered intramuscularly to 151 neonates ranging in birthweight from 0.66 to 4.7 kg (gestational age, 26-42 weeks) during a 7-month period. A dosage of 2.5 mg/kg of birthweight every 12 hours was initiated at birth until gentamicin serum levels could be determined. These infants were divided into three groups based on birthweight: 1) less than or equal to 1000 gm; 2) 1001-2000 gm; 3) greater than 2000 gm. From gentamicin serum level data, these three groups had significantly different (P less than 0.05) gentamicin half-lives. Based on the desirability of maintaining a trough gentamicin serum level less than 2, 100, 95.5, and 39% of infants in groups 1, 2, and 3, respectively, required initial dosing interval adjustments. A second group of 74 infants whose birthweight ranged from 0.82 to 3.9 kg (gestational age, 26-42 weeks) required aminoglycoside therapy and were prospectively placed on gentamicin 2.5 mg/kg of birthweight on the following schedule: 1) less than or equal to 1000 gm every 24 hours; 2) 1001-2000 gm every 18 hours; 3) greater than 2000 gm every 12 hours. Using this method, only 15, 58, and 33% of infants in groups 1, 2, and 3, respectively, required dosing interval changes. We conclude that a marked reduction in undesirably high trough gentamicin serum levels can be affected by a simple change in dosing interval based on birthweight, although gentamicin serum levels are still required due to a significant number of infants with high trough levels.     

Developmental aspects of phenobarbital dosage requirements in newborn infants with seizures

Although phenobarbital is the most widely used drug to control seizures, dosage guidelines are not available for infants of varying gestational ages. The primary objective of this study was to develop age specific dosage guidelines for phenobarbital in newborn infants with seizures. Fifty-one patients (27 premature infants, gestational ages 27 to 38 weeks; 24 term infants) receiving phenobarbital, 3 to 6 mg/kg/d were studied during the first month of life. Multiple serum concentrations were determined in each patient during extended therapy. Trough serum concentration of phenobarbital ranged from 12.5 to 50.2 mcg/mL. Phenobarbital serum concentrations were within therapeutic range (15 to 40 mcg/mL) in 99 of 114 measurements at a maintenance dose of 3.5 to 4.5 mg/kg/d. The remaining 15 measurements were made in infants, greater than 35 weeks' gestation and required phenobarbital doses of 4.0 to 5.0 mg/kg/d to achieve therapeutic serum concentration. These data suggest that the initial maintenance dose of phenobarbital during the first month of life should be 3.5 to 4.5 mg/kg/d in infants less than or equal to 35 weeks and 4.0 to 5.0 mg/kg/d in those greater than 35 weeks' gestation. Term infants with asphyxia had higher trough serum concentration than those without asphyxia (P less than 0.005). In nine infants, trough serum concentration normalized for dose decreased substantially during a 3-weeks period (P less than 0.0005). This suggests that phenobarbital serum concentration should be monitored frequently during the first month of life.     

Maternal zinc and cord blood zinc, insulin-like growth factor-1, and insulin-like growth factor binding protein-3 levels in small-for-gestational-age newborns

PURPOSE: To determine the relationship between maternal serum zinc (Zn) levels and birth weight of the offspring and their correlation with cord blood Zn, insulin-like growth factor (IGF-1) and insulin-like growth factor binding protein-3 (IGFBP-3) levels. METHOD: 22 term small-for-gestational-age (SGA) and 34 term appropriate-for-gestational-age (AGA) infants and their mothers were included. Maternal and cord blood Zn levels and cord blood IGF-1 and IGFBP-3 levels were measured. RESULTS: Eighteen percent of mothers had Zn deficiency (< 75 mcg/dl). No significant difference between IGF-1 and IGFBP-3 levels and birth weight of infants of the mothers with and without Zn deficiency was found. Maternal and neonatal Zn levels correlated (r = 0.38, p < 0.01). Mean IGF-1 and IGFBP-3 levels were significantly lower in the SGA group compared to the AGA group (42.3 +/- 16.8 ng/ml, 1.2 +/- 0.2 mcg/ml, and 62.4 +/- 22.7 ng/ml, 1.5 +/- 0.4 mcg/ml, p < 0.001). A correlation was found between birth weight, IGF-1 and IGFBP-3 levels, and weight gain of the mother during pregnancy (p < 0.01). CONCLUSIONS: Zn deficiency was not observed to be a risk factor for low birth weight. The significant difference between the SGA and AGA babies' IGF-1 and IGFBP-3 levels emphasizes function of the IGF system in intrauterine growth.     

The effects of syphilis on endocrine function of the fetoplacental unit

Several pregnancy complications that are thought to cause chronic intrauterine stress have been found to lead to inappropriate fetal development and reductions in estrogen production. In the current study we sought to evaluate the fetoplacental unit in pregnancies complicated by maternal syphilis (n = 37), with and without fetal infection. Maternal 17 beta-estradiol and estriol levels were reduced during the third trimester in women with syphilis when compared with those in women with uncomplicated pregnancies. Serum progesterone levels were within normal limits or else were increased in women with syphilis. When compared with data in age- and weight-matched control infants of women having no pregnancy complications, umbilical cord serum levels of dehydroepiandrosterone sulfate, the major fetal adrenal precursor of placental estrogens, were subnormal (897 +/- 597 ng/ml, mean +/- SD) in 12 newborn infants with congenital syphilis (33.9 +/- 4.2 weeks' gestation, birth weight 2020 +/- 719 gm); such infants also had excessive serum levels of cholesterol (103 +/- 37 mg/dl). Dehydroepiandrosterone sulfate (1883 +/- 907 ng/ml) and cholesterol (58.1 +/- 13.9 mg/dl) levels were within normal limits in 19 uninfected infants of women with syphilis (38.6 +/- 2.4 weeks' gestation, birth weight 2861 +/- 660 gm). Cortisol levels were increased and estriol levels were decreased in both groups of neonates of women with syphilis compared with those in control neonates. These findings are suggestive that estrogen production often is reduced in pregnancies complicated by syphilis; the reduction in estriol appears to be largely due to reduced fetal adrenal dehydroepiandrosterone sulfate production. The reduction in 17 beta-estradiol levels may be due to alterations in maternal precursor synthesis. Although placental progesterone formation appears to be normal in women with syphilis, a deficiency in placental aromatase activity also is possible.     

Serum ferritin levels in preterm infants after multiple blood transfusions

We have examined the effect on iron stores of blood transfusions given to premature neonates during hospitalization in the neonatal intensive care unit as reflected by serum ferritin levels measured for 6 months after discharge. Premature infants who were transfused with more than 100 ml packed cells (group D; n = 11) had higher ferritin levels for a longer period than premature infants who were transfused with smaller volumes (group c; n = 9) or premature and mature infants who were not transfused at all (group B; n = 24 and group A; n = 21, respectively). At 4-5 months the serum ferritin levels in group D (489.8 +/- 132.1 micrograms/L; mean +/- SEM) were significantly higher (P less than 0.001) than those of the other groups. The level of group A term infants (77.5 +/- 12.5 micrograms/L) was higher than those of group B premature infants who did not receive a blood transfusion (33.0 +/- 7.1 micrograms/L) or group C who received less than 100 ml (36.5 +/- 8.8 micrograms/L packed red blood cells. However, these differences were not statistically significant. Our data demonstrate that very-low-birthweight infants who receive a large volume of packed cells during hospitalization may accumulate iron stores sufficient for red cell production during the first 6 months of life. Administration of large amounts of supplemental iron, in such cases, may be curtailed.     

A blinded, randomized, multicenter study of an intravenous Staphylococcus aureus immune globulin.

OBJECTIVES: Very low birth weight (VLBW) infants are vulnerable to nosocomial infections and subsequent morbidity; including infections caused by Staphylococcus aureus: 85% of nosocomial S. aureus infections are caused by capsular polysaccharide (CPS) types 5 and 8. Altastaph is a polyclonal investigational human immunoglobulin G (IgG) with high levels of opsonizing S. aureus CPS types 5 and 8 IgG. METHODS: A Phase 2 clinical trial to assess the safety and kinetics of Altastaph in VLBW infants. Neonates in this multicenter study were randomized to receive two identical 20 ml/kg i.v. infusions of either 0.45% NaCl placebo or 1000 mg Altastaph/kg. Each infant was followed for 28 days after the second infusion or until discharge. Serum S. aureus CPS types 5 and 8 IgG levels were measured preinfusion and at various times after each infusion. RESULTS: Of 206 neonates, 158 received both infusions. Adverse events were similar in the two treatment groups. Six subjects (3% in each group) discontinued owing to an adverse event. Geometric mean anti-type 5 IgG levels were 402 and 642 mcg/ml 1 day following infusion of the first (day 0) and Second (day 14) doses, respectively, in neonates < or =1000 g and slightly higher in neonates 1001 to 1500 g. Trough levels before second infusion were 188 mcg/ml. Type 8 IgG levels were similar. Geometric mean IgG levels among placebo recipients were consistently <2 and <5 mcg/ml for types 5 and 8 in both weight groups. Three episodes of S. aureus bacteremia occurred in each arm. CONCLUSIONS: Infusion of Altastaph in VLBW neonates resulted in high levels of specific S. aureus types 5 and 8 CPS IgG. The administration of this anti-staphylococcal hyperimmune globulin was well tolerated in this population.     

Tobramycin dosing in the puerperal patient

Serum levels of tobramycin were determined with an enzyme immunoassay technique in 20 puerperal women with postcesarean endometritis who were being treated with metronidazole-tobramycin. Ideal dosing was then calculated to attempt to provide peak serum levels between 5 and 8 micrograms/mL and trough serum levels less than 2 micrograms/mL. In eight patients, therapeutic serum levels could not be attained even at doses greater than the package-insert recommendation of 3 mg/kg/d. Therapeutic levels were achieved in five patients with doses between 3 and 5 mg/kg/d and in seven patients only at doses above the maximum recommended daily dose of 5 mg/kg. The puerperal patient appears to usually require much higher dosages of tobramycin than usual, and serum levels must be monitored for therapeutic reasons rather than for toxicity.     

Daptomycin use in infants: report of two cases with peak and trough drug concentrations.

We report two infants treated with daptomycin for methicillin-resistant Staphylococcus aureus infection and describe peak and trough blood concentrations measured during therapy. The peak concentrations were 41.7 and 36.7 mcg ml(-1), and the 12-hour trough concentrations were 12.7 and 16.3 mcg ml(-1), respectively. Even though the infants received higher doses than adults, their drug concentrations were comparable to those observed in adults treated with regular dosing of daptomycin.     

Reliability of salivary theophylline in monitoring the treatment for apnoea of prematurity.

OBJECTIVE: To evaluate the reliability of salivary levels of theophylline in monitoring therapy of apnoea of prematurity. STUDY DESIGN: Aminophylline was administered intravenously in 13 infants with apnoea, in a loading dose of 5 mg/kg and maintenance dose of 3 mg/kg, every 8 h. The patients were divided into two groups according to their postconceptional age (PCA): group A, of infants with small PCA (32.8+/-2.0 weeks; n=6 cases), and group B, infants with higher PCA (37.1+/-0.8 weeks; n=7 cases). RESULTS: A total of 57 paired samples of serum and saliva were obtained in all 13 infants. The mean serum level of theophylline was 7.8+/-5.8 microg/ml and the ratio between serum and salivary concentration of theophylline was 1.53+/-0.28. A strong correlation between the serum and salivary concentration of theophylline (r=0.973) was found. Infants with small PCA had significant higher serum concentration of theophylline than those with higher PCA (10.6 vs 5.3 microg/ml; P=0.0002). The difference between the mean ratios of serum/salivary theophylline levels in the two groups was low (1.44 vs 1.62; P=0.0155). CONCLUSION: The strong correlation of theophylline in serum and in saliva recommends the salivary levels as a reliable method for monitoring the treatment of apnoea of prematurity.     

Hypoxic-ischemic encephalopathy: cerebrovascular carbon dioxide reactivity in neonates

Using noninvasive measurement of cranial blood flow, we previously demonstrated that full-term asphyxiated neonates have decreased cerebral perfusion that can persist up to 5 days of age. In an attempt to test their postischemic cerebrovascular CO2 reactivity, we measured cranial blood flow in ten asphyxiated term (39 +/- 0.8 weeks and 3078 K 400 gm) infants with and without inhaled carbon dioxide (3 percent). The end tidal CO2 (PaCO2) increased significantly, from 28.8 +/- 1.0 mm Hg to 32.3 +/- 2.0 mm Hg after CO2 inhalation (p less than 0.01), whereas the cranial blood flow showed no significant change (38.5 +/- 5.0 ml/min/100 gm brain weight to 37.6 +/- 6.0 ml/min/100 gm brain weight). We conclude that term infants with hypoxic-ischemic encephalopathy have low cranial blood flow at 3 days of age. Their cerebrovascular response to inhaled CO2 is variable and suggests some impairment.     

The effects of exercise on body weight and circulating leptin in premature infants.

OBJECTIVE: To assess the effect of daily movements on weight gain, serum leptin, and insulin-like growth factor I (IGF-I) in premature infants. STUDY DESIGN: Twenty very-low-birth-weight premature infants were matched and randomized to a daily movement (n = 10) and control groups (n = 10). Daily movement consisted of passive range of motion with gentle compression of both the upper and lower extremities 5 days per week for 4 weeks. RESULTS: Daily movements led to a significant increase in weight gain (784 +/- 51 vs 608 +/- 26 g in movements and controls, respectively, p < 0.02), and to a significant increase in leptin (0.60 +/- 0.19 vs 0.13 +/- 0.06 ng/ml in movements and controls, respectively 18.8 +/- 4.1 vs 9.2 +/- 4.1 ng/ml in movements and controls, respectively); however, this increase was not statistically significant. CONCLUSION: A relatively brief range of motion daily movement intervention was associated with greater weight gain and increased leptin levels in very-low-birth-weight premature infants. This may suggest that at least part of the daily movements associated with increase in body weight resulted from an increase in adipose tissue.     

Randomized trial of human versus animal species insulin in diabetic pregnant women: improved glycemic control, not fewer antibodies to insulin, influences birth weight.

OBJECTIVE: Macrosomia occurs in infants of diabetic mothers in spite of "nearly normal maternal blood glucose levels" with insulin treatment. Insulin antibodies may carry bound insulin into the fetal blood and thus may be associated with fetal hyperinsulinemia and macrosomia in these infants. Our objective was to test the hypothesis that human insulin is associated with lower insulin antibody levels and less macrosomia than is animal species insulin. STUDY DESIGN: Forty-three insulin-requiring pregnant (< 20 weeks' gestation) women, previously treated with animal insulin, were randomized to human and animal insulins and studied at weeks 10 through 20, 24, 28, 32, 36, and 38, at delivery, and at 3 months post partum. Infant blood was drawn at delivery (cord) and at 1 day and 3 months post partum 1 hour after a glucose-amino acid challenge. RESULTS: Women receiving human insulin required significantly less insulin per kilogram of body weight and showed significant dampening of glucose excursions (p < 0.05 for each comparison). Infants born to mothers receiving human insulin weighed 2880 +/- 877 gm compared with 3340 +/- 598 gm for infants of women treated with animal insulin (p < 0.05). There was no difference in insulin antibody levels between groups for either mothers or infants. Infants born to mothers receiving human insulin had a 1 hour C-peptide level after the glucose-amino acid challenge at 3 months of age of 0.21 +/- 0.13 pmol/ml compared with 0.32 +/- 0.13 pmol/ml (p = 0.01). CONCLUSION: Administration of human insulin to pregnant diabetic women has a therapeutic advantage over animal insulin, with less maternal hyperglycemia or hypoglycemia, fewer larger-for-gestational-age infants, and less neonatal hyperinsulinemia. Our data do not support the hypothesis that maternal antibodies to insulin influence infant birth weight.     

Cumulative increase in serum furosemide concentration following repeated doses in the newborn

In order to test whether repeat doses of the diuretic furosemide result in plasma accumulation of this drug, eight newborns (mean birthweight, 1252 gm; mean gestational age, 27.5 weeks; mean postnatal age, 44.7 days; and normal renal function) were each given a 1-mg/kg iv bolus every 12 hr for four doses and maintained normally hydrated throughout the study period. Serum furosemide peak concentrations (1 hr after administration) were measured in eight newborns, and trough levels in four newborns, by HPLC. The mean 1-hr serum furosemide level increased with repeated doses of the drug, from 3.18 +/- 0.52 to 7.95 +/- 2.36 mg/liter (mean +/- SE) (p less than .05). In contrast, the mean serum trough concentration of furosemide remained at a plateau following the first dose (1.8 +/- 0.82 to 1.98 +/- 1.81 mg/liter), suggesting attainment of a steady state. This accumulation of furosemide following repeated doses of this diuretic, therefore, reflects the decreased plasma clearance of the drug, possibly due to contraction of its volume of distribution.     

Clinical usefulness of estimation of serum fructosamine concentration as screening test for gestational diabetes

Serum fructosamine levels and fructosamine/protein ratios were measured in 100 pregnant women who underwent glucose tolerance tests because of clinical risk. Compared with normal pregnant women, the 13 study participants with gestational diabetes had higher fructosamine/protein levels (39 +/- 3.9 mumol/gm versus 37 +/- 3.2 mumol/gm, p less than 0.05), fasting serum glucose levels (107 +/- 13.7 mg/dl versus 82 +/- 8.6 mg/dl, p less than 0.001), and area under curve of glucose tolerance test (36 +/- 5 gm x min x dl-1 versus 22 +/- 3.6 gm x min x dl-1, p less than 0.001). The serum fructosamine levels were not significantly different between the two groups of participants (2.3 +/- 0.26 mmol/L versus 2.2 +/- 0.17 mmol/L); 10 of the 13 women with diabetes had a fructosamine/protein ratio within 2 SD of the mean of the groups of normal pregnant women. Spontaneous caloric intakes (r = 0.72, p less than 0.005) and the hospital mean daily capillary glucose levels during diabetic diet (r = 0.72, p less than 0.005) correlated better with the fructosamine/protein ratio than with fasting serum glucose levels (r = 0.58, p less than 0.05) and area under curve (r = 0.57, p less than 0.05). Consequently, serum fructosamine and fructosamine/protein ratio levels should be considered insensitive as a screening test in pregnant patients with clinical risk of gestational diabetes.     

The relationship between trough drug concentrations and ductal closure in preterm infants treated with three-dose-oral ibuprofen

Abstract

The aim of the present study was to characterize the pharmacokinetic profile of oral ibuprofen on consecutive 3?d by trough serum levels, and if possible to define a cut-off level for ductal closure in preterm infants. The study enrolled 20 preterm infants with gestational age ≤30 weeks, birth weight <1250?g and hemodynamically significant patent ductus arteriosus (hsPDA). Patients received oral ibuprofen at an initial dose of 10?mg/kg, followed by 5?mg/kg at 24 and 48?h. Patients were compared for serum ibuprofen levels in addition to their demographic and clinical data in case of their response to the treatment. hsPDA closed in 16 (80%) of the patients. Although mean ibuprofen levels on consecutive 3?d showed a plateau in general, ibuprofen serum levels on the first treatment day were statistically low in patients with unclosed hsPDA (p?=?0.003). The optimal cut-off value for serum ibuprofen level on the first treatment day was measured as 5.5?mg/l with 100% sensitivity and 93% specificity. Serum ibuprofen level on the first treatment day seems to be an important factor for a successful ductal closure. Target concentration approach by the evaluation of trough level may be applicable to real-time dosing strategy.     

Maternal serum cytokine levels in pregnancies complicated by PROM

OBJECTIVE: The aim of the study was to evaluate the maternal serum cytokines levels in pregnancies complicated by premature rupture of membranes (PROM). MATERIALS AND METHODS: Maternal serum of IL-1 beta, IL-4, IL-6, IL-8 and TNF-alfa levels were assessed in patients with PROM between 24-34 weeks of pregnancy (n = 45). Control group consisted of healthy pregnant women (n = 41) at 24-34 weeks of gestation. Serum cytokines concentrations were measured by commercial available enzyme-linked immunosorbent assays. C-reactive protein level and WBC were estimated in both groups. RESULTS: Compared to healthy pregnant, the group of patients with PROM had significantly higher serum levels of IL-1 beta (0.76 pg/ml vs 0.41 pg/ml, p = 0.022), TNF-alfa (1332.46 pg/ml vs 58.01 pg/ml, p < 0.00001) and IL-8 (15.79 pg/ml vs 0 pg/ml, p < 0.00001). CRP concentration and WBC were also significantly higher in serum of pregnant women with PROM then in healthy ones (CRP: 10 mg/l vs 0 mg/l, p = 0.043; WBC: 13,188 +/- 3625/mm3 vs 9132 +/- 1913/mm3, p < 0.00001). No significant differences in IL-6 and IL-4 levels were found between groups. CONCLUSION: Differences in serum maternal levels of cytokines between patients with premature ruptures of membranes and healthy pregnant women suggest that reasons and/or consequences of PROM results in changes in immunological system.     

The startle reaction of the newborn infant

Startle characterized by a spontaneous or reflecting motoric symptom like brisk, shortlasting and generalized contraction of limb and trunk muscles influence considerably the cardio-respirogram of neonates. The dependence of startles on behaviour, gestational age and postnatal age as well as on levels of blood glucose, calcium and magnesium in serum has been studied in 12 premature infants and in 24 full term neonates by means of polygraphic conditions. The average of 3.6 +/- 3.0 complete startles in premature infants and of 10.6 +/- 8.7 startles in full term neonates per hour non rapid eye movement-sleep, observed on second day after birth, was significantly higher than the frequency of startles in rapid eye movement-sleep measured as 0.6 +/- 0.9 and 1.9 +/- 2.1 complete startles respectively. In an age of 4 weeks there were no complete startles demonstrable in full term neonates and only 0.2 complete startles/h in non rapid eye movement sleep could be observed in premature infants. There was no correlation between frequency of startles and investigated chemical parameters in serum.     

Characteristics associated with successful weaning in ventilator-dependent preterm infants.

Eighteen ventilator-dependent preterm infants with hyaline membrane disease were studied for 24 hours before and after an attempt at extubation. All were treated with theophylline prior to weaning and achieved average levels of 8.9 +/- 1.7 micrograms/ml (49 +/- 9 mumol/liter) in 13 successfully weaned infants and 8.4 +/- 1.1 micrograms/ml (47 +/- 6 mumol/liter) in 5 infants not extubated, p > 0.05. Infants successfully weaned were significantly (p < 0.01) older, more mature (29 +/- 1 versus 26 +/- 2 weeks' gestational age) and heavier (1107 +/- 236 versus 1016 +/- 256 gm) than infants not successfully extubated. Infants successfully weaned differed only in developing a greater maximal inspiratory force (33.8 +/- 12.3 versus 23.3 +/- 15.0 cm H2O) and higher compliance (1.1 +/- 0.3 versus 0.7 +/- 0.3) during the preweaning treatment period. These results indicate that maturity and size play a significant role in the ability to wean a preterm infant from the ventilator successfully, that maximal inspiratory force and compliance are higher in preterm infants who can be successfully extubated, and that methylxanthines do not uniformly improve pulmonary function in all potentially extubatable preterm infants.     

THE AUSTRALIAN & NEW ZEALAND JOURNAL OF OBSTETRICS & GYNAECOLOGY

In order to assess the possible influence of fetal polypeptide hormones on birth size, somatomedin-like receptor activity (SmLRA) (n = 281), prolactin (n = 158), growth hormone (n = 133) and insulin (n = 108) concentrations were measured in the cord blood of 281 singleton infants born after different complications of pregnancy. Infant sex did not significantly affect the concentration of any hormone. SmLRA concentrations appeared to rise from 25 to 38 weeks of gestation, but thereafter fell. Concentrations of prolactin, growth hormone and insulin correlated negatively with gestational age. Insulin emerged as the hormone most clearly related to fetal growth, since concentrations were high (mean +/- SD = 20.6 +/- 11.5 uU/ml) in serum from infants of diabetic mothers (IDM) and other large-for-dates infants (10.1 +/- 4.8 uU/ml), but low (5.3 +/- 0.5 uU/ml) in infants who were small-for-dates (SFD). In contrast, SmLRA concentrations were high in serum from SFD infants (0.63 +/- 0.29 U/ml) and low in IDM (0.43 +/- 0.16 U/ml). Prolactin concentrations were higher in serum from SFD infants (212 +/- 101 ng/ml) and from IDM (237 +/- 182 ng/ml) than from normal infants born at term (139 +/- 68 ng/ml). Administration of intramuscular betamethasone to pregnant women in premature labour resulted in significant elevations in the concentrations of prolactin and insulin in cord blood.