Effects of Shoal Margin Collapses on the Morphodynamics of a Sandy Estuary.

Shoal margin collapses of several million cubic meters have occurred in the Western Scheldt estuary, the Netherlands, on average five times a year over the last decades. While these collapses involve significant volumes of material, their effect on the channel-shoal morphology is unknown. We hypothesize that collapses dynamicize the channel-shoal interactions, which could impact the ecological functioning, flood safety, and navigation in the estuary. The objective is to investigate how locations, probability, type, and volume of shoal margin collapse affect the channel-shoal dynamics. We implemented an empirically validated parameterization for shoal margin collapses and tested its effect on simulated estuary morphological development in a Delft3D schematization of the Western Scheldt. Three sets of scenarios were analyzed for near-field and far-field effects on flow pattern and channel-shoal morphology: (1) an observed shoal margin collapse of 2014, (2) initial large collapses on 10 locations, and (3) continuous collapses predicted by our novel probabilistic model over a time span of decades. Results show that a single shoal margin collapse only affects the local dynamics in the longitudinal flow direction and dampen out within a year for typical volumes, whereas larger disturbances that reach the seaward or landward sill at tidal channel junctions grow. The direction of the strongest tidally averaged flow determined the redistribution of the collapsed sediment. We conclude that adding the process of shoal margin collapses increases the channel-shoal interactions and that in intensively dredged estuaries shoal margins oversteepen, amplifying the number of collapses, but because of dredging the natural morphological response is interrupted.

Effect of storage on breast milk antioxidant activity.

BACKGROUND: Human milk, which contains compounds beneficial to infants, is often expressed and stored before use. Changes in its antioxidant activity with storage have not been studied. OBJECTIVES: To measure antioxidant activity of fresh, refrigerated (4 degrees C), and frozen human milk (-20 degrees C), stored for two to seven days; to compare the antioxidant activity of milk from mothers delivering prematurely and at term; to compare the antioxidant activity of infant formulas and human milk. METHODS: Sixteen breast milk samples (term and preterm) were collected from mothers within 24 hours of delivery and divided into aliquots. Fresh samples were immediately tested for antioxidant activity, and the rest of the aliquots were stored at -20 degrees C or 4 degrees C to be analysed at 48 hours and seven days respectively. The assay used measures the ability of milk samples to inhibit the oxidation of 2,2'-azino-di-3-(ethylbenzthiazolinesulphonate) to its radical cation compared with Trolox. RESULTS: Antioxidant activity at both refrigeration and freezing temperatures was significantly decreased. Freezing resulted in a greater decrease than refrigeration, and storage for seven days resulted in lower antioxidant activity than storage for 48 hours. There was no difference in milk from mothers who delivered prematurely or at term. Significantly lower antioxidant activity was noted in formula milk than in fresh human milk. CONCLUSIONS: To preserve the antioxidant activity of human milk, storage time should be limited to 48 hours. Refrigeration is better than freezing and thawing.

Screening processed milk for volatile organic compounds using vacuum distillation/gas chromatography/mass spectrometry.

An adaptation is presented of method 8261--from the Office of Solid Waste and Emergency Response Test Methods for Evaluating Solid Waste Physical/Chemical Methods (SW-846)-to analyze milk for an expanded list of volatile organic compounds is presented. The milk matrix exhibits a strong affinity for organic compounds and the surrogate based matrix normalization described in method 8261 provided accurate results. This method had the sensitivity necessary to detect volatile organic analytes at or below maximum contaminant levels (MCLs) set by EPA for drinking water. In a survey of milk samples available in Las Vegas, Nevada, 32 of 88 targeted volatile organic compounds (VOCs) were detected. Many of the detected VOCs have not previously been reported and a rationale for their presence in milk is presented.

Urinary thiobarbituric acid-reacting substances as potential biomarkers of intrauterine hypoxia.

BACKGROUND: Currently available clinical tools cannot accurately identify the extent of perinatal hypoxic injuries. During hypoxia, reactive oxygen species cause lipid peroxidation of cell membranes, yielding oxidation products that constitute thiobarbituric acid-reacting substances (TBARS). OBJECTIVE: To see if the concentrations of TBARS excreted in urine would be elevated during the first day of life in term and preterm infants following chronic hypoxia or acute asphyxia. DESIGN: Thiobarbituric acid-reacting substances levels were measured by a spectrophotometric assay in urine samples collected from term and near-term (>/= 34 weeks gestation, n = 22), and preterm (<34 weeks gestation, n = 52) infants on the first day of life. PATIENTS: Infants were admitted to the St Peter's University Hospital (New Brunswick, NJ) neonatal intensive care unit from July 1997 to January 1999. Acute asphyxia was defined as umbilical cord blood pH values less than 7.05, or Apgar scores of less than 5 at 5 minutes. Chronic hypoxia was defined as intrauterine growth retardation or low birth weight (small for gestational age) associated with pregnancy-induced hypertension or reversal of umbilical arterial blood flow. RESULTS: Among term infants, urinary TBARS levels were significantly increased following acute asphyxia (P =.02). Levels of TBARS also tended to be elevated following chronic hypoxia. Urinary TBARS levels in term infants tended to be increased in those requiring mechanical ventilation (P =.05) or delivery room resuscitation (P =.15), as well as in those passing intrauterine meconium (P =.13) or having clinical evidence of hypoxic-ischemic encephalopathy (P =.24). CONCLUSIONS: The results show a correlation between elevated urinary TBARS levels in term and near-term infants, and perinatal hypoxia (as determined by low Apgar scores or umbilical cord blood acidosis). We speculate that TBARS concentrations may be useful as a biomarker for perinatal hypoxic injury in newborns. Further studies are needed to determine whether elevations in TBARS levels are better predictors of the extent of hypoxic injury than existing markers.

Effects of perinatal hypoxia on serum unbound free fatty acids and lung inflammatory mediators.

Cellular injury during tissue hypoxia is due, in part, to reactive intermediates released by activated leukocytes. We found that the inflammatory mediators tumor necrosis factor (TNF)-alpha, IL-6, and IL-1beta are elevated in situ in lung macrophages on day 14 following exposure of rats to intermittent or chronic hypoxia from birth. Because inflammatory mediators can increase lipolysis in adipocytes, we also measured serum unbound free fatty acids (FFAu)--the biologically active compartment of FFA--in rat pups exposed to intermittent or chronic hypoxia. FFAu values were markedly elevated during the first 2 days of life in all rats, displaying an approximately 3-fold decrease from day 2 to day 3. Exposure to chronic hypoxia significantly increased FFAu levels measured on day 13. Since elevated serum FFAu are known to suppress leukocyte activation, we speculate that increased FFAu levels represent a mechanism for attenuating inflammation and tissue injury following sublethal hypoxia in the perinatal period, either physiologically in the immediate newborn period, or as a late response to ongoing hypoxic insult.

Topographic mapping of brain potentials in the newborn infant: the establishment of normal values and utility in assessing infants with neurological injury.

AIM: To demonstrate that quantitative EEG (qEEG) can be used as a non-invasive measure of brain injury by establishing normative data in term infants and contrasting it with other modalities of brain imaging. DESIGN: qEEG during quiet sleep was performed on 13 healthy full-term infants comprising a normal group and on 10 infants with neurological abnormalities identified on brain imaging studies (abnormal group) at 36-47 wk postconceptional age. Quantitative analysis was performed and topographic maps were produced for each patient. The EEG data from the normal group, after spectral analysis, yielded power data in the delta, theta, alpha, and beta frequency bands and coherence information, which then formed the normative database. qEEG from the infants in the abnormal group was then compared to this normative data. RESULTS: The normal group's mean absolute power in the delta, theta, alpha, and beta bands for all EEG leads combined were 278.48+/-83.83, 31.71+/-10.12, 29.20+/-2.04, and 35.76+/-11.35 uv2, respectively. The median frequency was 1.49+/-0.07, 5.45+/-3.46, 9.74+/-5.11, and 18.01+/-3.38 Hz, respectively. The qEEG was abnormal in all 10 study infants, while abnormalities were noted in the clinical EEG in 4 of 10, in the neuroultrasound in 5 of 10, in the CT in one of 6, and in the MRI in 2 of 2 tested. CONCLUSIONS: qEEG appears to be a useful non-invasive method for measuring brain injury as it correlates well with other modalities of brain imaging and, if corroborated by further study, may, in fact, be more sensitive in determining abnormalities in brain function.

The length of time necessary to break even after converting to digital mammography.

The cost differences between film-based mammography (FBM) and digital mammography (DM) were estimated after discussions with hospital personnel and industry representatives. Human resource costs were not included. The fixed cost of FBM per machine was estimated to be $50,000 and the variable cost $4.60 per examination. The fixed cost of DM per machine was estimated to be $102,000 and the variable cost $0.10 per examination. The total number of examinations required to break even was therefore 11,556. At a rate of 15 examinations per machine per day and with 251 working days per year, it would take 3.1 years to break even. In the first year after the break-even point had been attained, $16,943 would be saved for every 3765 examinations performed. Extrapolating to the USA as a whole, in which 23 million mammographic examinations are performed each year, suggests that the annual savings from going filmless would be more than $103 million.

Spectral analysis of heart variability in the newborn infant.

We investigated the relationship between spectral power and both mean heart rate (HR) and heart rate variability (HRV). Spectral power was calculated using digital heart rate recordings from term infants. Regression analysis revealed a positive correlation between low-frequency (LF) sympathetic power and HR, and a negative correlation between high-frequency (HF) parasympathetic power and HR. HRV correlated positively in all regions of the power spectrum. In awake infants, the contribution of HF power to total power (HF/TP) was significantly decreased. LF power tended to be greater, however, this trend was not statistically significant. By following expected autonomic patterns, the findings of this study confirm that spectral analysis provides a noninvasive method for the assessment of autonomic activity influencing the newborn heart. The correlation between spectral power and HRV can serve as an additional tool in the study of autonomic dysfunction.

Antioxidant capacity and oxygen radical diseases in the preterm newborn.

BACKGROUND: Bronchopulmonary dysplasia, intraventricular hemorrhage, necrotizing enterocolitis, and retinopathy of prematurity may be different manifestations of oxygen radical diseases of prematurity (ORDP). OBJECTIVE: To test the hypothesis that the antioxidant capacity of cord blood serum will predict risk of ORDP. DESIGN: An inception cohort of premature neonates was followed up from birth until discharge or death to determine if outcome was related to cord blood serum antioxidant capacity, as determined by a manual assay measuring the relative inhibition of oxidation of 2,2'-azino-di-(3-ethylbenzthiazoline)-6 sulfonic acid (ABTS). Possible correlations between antioxidant capacity and various perinatal factors were also tested. SETTING: Level 3 newborn intensive care unit. PATIENTS: All inborn very low-birth-weight neonates from whom cord blood was available and for whom maternal consent was obtained were included. Newborns who died in the first week of life or who had major congenital malformations were excluded. A convenience sample of newborns weighing more than 1500 g was used to perfect assay and explore confounders. MAIN OUTCOME MEASURES: Significant ORDP was defined as the presence of intraventricular hemorrhage greater than grade 2, retinopathy of prematurity greater than stage 1, bronchopulmonary dysplasia at the postconceptional age of 36 weeks, or necrotizing enterocolitis with the hypothesis that neonates with ORDP will have lower antioxidant capacity in cord blood serum. RESULTS: Serum antioxidant capacity at birth correlated with gestational age for the entire sample of 41 neonates and for the 26 neonates born before 32 weeks' gestation. After correction for gestational age, cord serum antioxidant capacity did not correlate with maternal smoking, preeclampsia, chorioamnionitis, cord pH Apgar scores, or any of the ORDP studied. CONCLUSION: Cord serum antioxidant capacity correlates with gestational age but does not predict ORDP risk.

Spectral analysis of heart rate variability in premature infants with feeding bradycardia.

An elevated level of baseline parasympathetic activity was noted in a group of premature infants suffering from bradycardia during feeding. At approximately 34 wk post-conceptional age, the heart rates of 12 infants with feeding bradycardia (birth weight = 1539 +/- 279 g; gestational age = 31.0 +/- 1.6 wk) and 10 controls (birth weight = 1710 +/- 304 g; gestational age = 32.0 +/- 1.4 wk) were recorded 1 h before and 1 h after feeding. EKG data were digitized and 3.2-min segments of data were analyzed to determine the spectral power at very low (VLF = 0.003-0.03 Hz), low (LF = 0.03-0.39 Hz), and high (HF = 0.40-1.00 Hz) frequencies. In preterm infants with feeding bradycardia, an elevation in baseline parasympathetic activity was evident before feeding, as indicated by significantly higher HF power and a lower LF/HF ratio. This elevation in baseline parasympathetic activity may contribute to the observed bradycardia during feeding.

Umbilical vein interleukin 6 and tumor necrosis factor alpha plasma concentrations in the very preterm infant.

OBJECTIVE: To examine the relationship between umbilical vein plasma concentrations of interleukin 6 (IL-6) and tumor necrosis factor (TNF)-alpha and early neonatal sepsis in the very preterm infant, and the histopathologic findings of chorioamnionitis in the placentas from these pregnancies. METHODS: A prospective study was conducted in 43 very preterm, singleton infants delivered at or before 32 weeks of gestation. IL-6 and TNF-alpha were measured by enzyme-linked immunoassay. Placentas from these pregnancies were histologically examined for the presence of chorioamnionitis. Infants were prospectively classified as confirmed sepsis group, clinical sepsis group or control group. IL-6 and TNF-alpha plasma concentrations were not normally distributed, so they were transformed to their natural log values for statistical analysis. RESULTS: The enrolled infants had a mean gestational age of 27.2 +/- 2.7 weeks and a mean birth weight of 956 +/- 325 g. Three (7%) infants had confirmed sepsis, 18 (42%) were in the clinical sepsis group and 22 (51%) were in the control group. IL-6 concentrations but not TNF-alpha were significantly higher (P < 0.05) in the confirmed (8.9 +/- 1.7) and clinical sepsis (5.5 +/- 2.4) groups in comparison with the control group (2.1 +/- 1.6). We examined 42 placentas. Twenty-three (55%) had no evidence of chorioamnionitis, 1 (2%) had mild grade, 8 (19%) had a moderate grade and 10 (24%) had a severe grade of chorioamnionitis. IL-6 was significantly elevated in the moderate (5.9 +/- 1.6 vs. 1.9 +/- 1.6) and severe grade (7.2 +/- 2.3 vs. 1.9 +/- 1.6) of chorioamnionitis, in the presence of acute deciduitis (6.0 +/- 2.7 vs. 2.1 +/-1.8), chorionic vasculitis (6.8 +/- 2.1 vs. 2.2 +/- 1.9) and funisitis (7.3 +/- 1.9 vs. 2.7 +/- 2.3) (P < 0.05) TNF-alpha plasma concentrations were not significantly different. CONCLUSION: An elevated umbilical vein IL-6 concentration is a good indicator of sepsis syndrome in the very preterm infant and also correlates with histologic chorioamnionitis in these pregnancies.

Antecedents and neonatal consequences of low Apgar scores in preterm newborns: a population study.

BACKGROUND: To examine the antenatal and early neonatal correlates of low Apgar scores (<3 and <6 at 1 and 5 minutes) in preterm newborns (23-34 weeks' gestation). OBJECTIVE: The use of Apgar scoring for premature newborns remains widespread, despite controversy regarding its reliability as a measure of morbidity and mortality in the neonatal period. DESIGN: A cohort of 852 preterm newborns born during a 34-month period between 1984 and 1987 was studied. Newborns were stratified into 2 groups by gestational age (23-28 weeks and 29-34 weeks), and data were analyzed, controlling for gestational age in single weeks. SETTING: Two academic and 1 community hospital, which together accounted for 83% of all preterm births in a tri-county area of central New Jersey during the study period. PATIENTS: All premature newborns (birth weight <2000 g and gestational age <35 weeks) born in the participating hospitals during the study period were evaluated. MAIN OUTCOME MEASURES: Antecedents included maternal illness during pregnancy, maternal complications of labor and delivery, and fetal heart rate abnormalities during labor and delivery. Consequences included delivery room resuscitation, abnormal physical findings, diagnoses, and therapeutic interventions in the first 6 to 8 hours of life. RESULTS: Premature newborns with low Apgar scores received more cardiopulmonary resuscitation in the delivery room and in the first 6 to 8 hours of neonatal intensive care. Mortality was significantly increased among newborns with low Apgar scores (54% vs. 26% in the 23- to 28-week stratum, 30% vs 6% in the 29- to 34-week stratum). Newborns with low Apgar scores in the 29- to 34-week stratum more often required intubation, positive pressure ventilation, and umbilical vessel catheterization. Newborns with low Apgar scores had higher rates of bradycardia, pneumothoraces, acidosis, and increased oxygen requirement during the first 6 to 8 hours of life. Maternal illness, complications of labor and delivery;, and fetal heart rate decelerations did not correlate with subsequent Apgar scores of newborns. The presence of severe bradycardia (<90/min) and fetal heart rate accelerations correlated with low Apgar scores in the 29- to 34-week group. CONCLUSION: Low Apgar scores are associated with increased neonatal morbidity and mortality in preterm newborns. Antenatal maternal history, and pregnancy complications are not clearly associated with low Apgar scores. Therefore, the Apgar score is a useful tool in assessing neonatal short-term prognosis and the need for intensive care among preterm newborns.

The decision to salvage or amputate a severely injured limb.

The decision to salvage or amputate a severely injured limb is one of the most difficult an orthopaedic surgeon may face. The inclination to undertake heroic measures to save the limb should be tempered by the realization that doing so may lead to repeated hospitalizations, extensive complications, and a poor functional outcome. Several factors must be considered, including objective elements related to the patient's injury and physical condition and subjective considerations related to the patient's psychologic, social, and economic status. We present a framework, in the context of a case study, which may be used in deciding which patients can benefit from early amputation and review five predictive indices for limb salvage.

Maternal behavior toward premature twins: implications for development.

Assisted reproductive techniques and fertility enhancing therapies have increased multiple births and, therefore, the risk of prematurity and its developmental consequences. Parent intervention is an effective source of compensation for the cognitive effects of prematurity. We hypothesized that relative to parents of preterm singletons, parents of preterm twins are less able to provide such enhancing care, resulting in a developmental disadvantage for preterm twins. Maternal-infant interactions of premature singletons (n = 22; birth weight = 1668 +/- 350 g, gestational age = 32.3 +/- 2.1 weeks) and premature twins (n = 8; birth weight = 1618 +/- 249 g; gestational age = 32.0 +/- 2.6 weeks) with comparable demographic and medical status were observed at home at 1 and 8 months corrected age using a 30 min checklist of developmentally facilitative behavior. Mental (MDI) and psychomotor (PDI) indices of the Bayley Scales of Infant Development and Caldwell Home Observations for Measurement of the Environment (HOME) inventories were administered (18 months corrected age). Compared with mothers of premature singletons, mothers of premature twins exhibited fewer initiatives (P < 0.001) and responses (P < 0.01) and were less responsive to positive signals (P < 0.01) and crying (P < 0.01). Unprompted by the infant, twin mothers lifted or held (P < 0.05), touched (P < 0.01), patted (P < 0.05) or talked (P < 0.01) less. Singleton MDIs surpassed twins (119.4 +/- 7.7 vs 103.6 +/- 7.7; P < 0.01). Maternal verbal behavior and the acceptance of child factor (HOME), both favoring singletons, correlated with MDI (R-square = 0.46, P < 0.0002). Mothers of premature twins exhibited fewer initiatives and responses toward offspring than did mothers of premature singletons. Maternal behavior was predictive of cognitive development.

Maternal infection, fetal inflammatory response, and brain damage in very low birth weight infants. Developmental Epidemiology Network Investigators.

Echolucent images (EL) of cerebral white matter, seen on cranial ultrasonographic scans of very low birth weight newborns, predict motor and cognitive limitations. We tested the hypothesis that markers of maternal and feto-placental infection were associated with risks of both early (diagnosed at a median age of 7 d) and late (median age = 21 d) EL in a multi-center cohort of 1078 infants <1500 x g. Maternal infection was indicated by fever, leukocytosis, and receipt of antibiotic; fetoplacental inflammation was indicated by the presence of fetal vasculitis (i.e. of the placental chorionic plate or the umbilical cord). The effect of membrane inflammation was also assessed. All analyses were performed separately in infants born within 1 h of membrane rupture (n = 537), or after a longer interval (n = 541), to determine whether infection markers have different effects in infants who are unlikely to have experienced ascending amniotic sac infection as a consequence of membrane rupture. Placental membrane inflammation by itself was not associated with risk of EL at any time. The risks of both early and late EL were substantially increased in infants with fetal vasculitis, but the association with early EL was found only in infants born > or =1 after membrane rupture and who had membrane inflammation (adjusted OR not calculable), whereas the association of fetal vasculitis with late EL was seen only in infants born <1 h after membrane rupture (OR = 10.8; p = 0.05). Maternal receipt of antibiotic in the 24 h just before delivery was associated with late EL only if delivery occurred <1 h after membrane rupture (OR = 6.9; p = 0.01). Indicators of maternal infection and of a fetal inflammatory response are strongly and independently associated with EL, particularly late EL.

Thrombolytic therapy with streptokinase and tissue plasminogen activator in a patient with suspected acute myocardial infarction: A decision analysis.

Two commonly used thrombolytic agents are streptokinase (SK) and tissue plasminogen activator (t-PA), which have different impacts on the incidence of mortality and thrombolysis-related acute intracranial hemorrhage. A decision-analytic model was developed to compare the use of SK and t-PA in the treatment of a patient with suspected acute myocardial infarction (AMI). The outcome was health-related quality of life as quantified in a measure of utility from the patient's point of view. The model included three outcome states: death, nonfatal yet disabling stroke, and survival with no disabling stroke. The utility for disabling stroke was determined relative to the reference states of no disabling stroke (1.00) and death (0.00) by means of the time trade-off estimation technique. Probabilities were derived from the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Artery trial, which revealed that although administering t-PA results in a lower percentage of deaths compared to SK, it may lead to a higher percentage of strokes. A decision tree was constructed to model the options and outcomes. The tree was analyzed by standard decision analytic techniques using SMLTREE software, and the stability of the results was examined as values of parameters were varied systematically in a sensitivity analysis. In the baseline analysis, SK yielded 0.9235, whereas t-PA yielded 0.9329. The sensitivity analysis revealed that if the probability of a disabling stroke attributable to t-PA were greater than 2.08%, SK would yield the higher expected utility. This threshold value, however, was much greater than the probability established in major trials. The administration of t-PA leads to a slightly better outcome than does the administration of SK in a patient with suspected AMI.

Concurrent validity of the Millon Adolescent Clinical Inventory as a measure of depression in hospitalized adolescents.

This study examined the concurrent validity of the Millon Adolescent Clinical Inventory (MACI; Millon 1993) in the assessment of depression among 88 adolescent inpatients. Doleful Personality and Depressive Affect scales were moderately predictive of a clinical diagnosis of depression, but both scales were strongly associated with scores on the Children's Depression Inventory (Kovacs, 1992). The Suicidal Tendencies scale was weakly associated with placement on suicide precautions. Overall, these results provide moderate support for the use of the MACI in the assessment of hospitalized adolescents.

Heart rate and oxygen saturation correlates of infant apnea.

OBJECTIVE: To analyze the effects of apnea duration on changes in heart rate and oxygen saturation and to examine the temporal relationships among these variables. STUDY DESIGN: An event analysis sheet was designed to analyze numerous variables reflecting changes in heart rate and oxygen saturation associated with infant apnea. From July 1, 1991 through June 30, 1992 we identified 32 infants enrolled in The Infant Apnea Program at St. Peter's Medical Center, New Brunswick, NJ who had apnea > or = 15 seconds in duration on consecutive 12-hour multichannel recordings of heart rate, thoracic impedance, nasal thermistry, and oxygen saturation. The apnea epochs of these patients were subdivided into apnea of short (10 to 14 seconds), medium (15 to 19 seconds), and long (> or = 20 seconds) duration, and a total of 236 apnea epochs were analyzed. The significance of differences was assessed by analysis of variance and Newman-Keuls multiple comparisons. RESULTS: We found that the duration of apnea has significant effects on perturbations in both heart rate and oxygen saturation, however, the degree of oxygen desaturation can not be predicted by the perturbation in heart rate. Analysis of the temporal relationship of apnea, bradycardia, and oxygen desaturation reveals that, although apnea precedes both heart rate and oxygen saturation drops in most infants as the length of apneic interval increases, the interval between apnea onset and associated drops in heart rate and/or oxygen saturation also increases. CONCLUSION: Oxygen saturation monitoring may provide important physiologic data that can not be assessed by cardiorespiratory monitoring alone.

The apgar score and its components in the preterm infant.

OBJECTIVE: The Apgar score is well-characterized in full-term infants but not in premature infants. The objective of this study was to assess the Apgar score in preterm infants with respect to the relationships between the 1- and 5-minute scores, the correlation of the Apgar score with pH and with other variables, and the relationship among the individual Apgar components. METHODOLOGY: We recorded Apgar scores at 1 and 5 minutes in a population-based cohort of preterm infants (n = 1105) with birth weight <2000 g, from three intensive care nurseries in central New Jersey. Linear correlation analysis was used to examine the relationship between 1- and 5-minute Apgar scores and between the individual components of the Apgar score. Multiple regression analysis was used to explore the relationship between various perinatal characteristics and the Apgar score, and between pH and Apgar score. Stepwise logistic regression analysis was used to assess the determinants of mortality. RESULTS: The 1-minute Apgar score median (25%, 75%) was 6(4,8) and correlated with the 5-minute score of 8(7,9) at r = .78. Slight but significant differences were seen between male (n = 557) and female (n = 508) infants in the 1-minute (6[4,8] and 7[4,8]) Apgar scores. One- and 5-minute scores of white infants (7[4,8] and 8[7,9]; n = 713) were significantly higher than those of black infants (5[3,7] and 8[6,9]; n = 280). Birth weight and gestational age were both linearly related to both Apgar scores. Low Apgar score (<3 at 1 minute and <6 at 5 minutes) was significantly associated with birth weight, gestational age and mode of delivery. Low arterial blood pH (<7.01) at birth was significantly related to low Apgar score. One hundred fifty-nine infants died; these infants were significantly smaller (983 +/- 382 vs 1462 +/- 369 g), less mature (27 vs 31 weeks), had lower arterial blood pH (7.20 +/- 0.18 vs 7.31 +/- 0.11), had lower 1- (3[2,6] vs 7[4,8]) and 5-minute Apgar scores (6[4,8] vs 8[7,9]), and a greater incidence of low Apgar score (32% vs 6%) than did survivors. CONCLUSIONS: Among the components of the Apgar score, respiratory effort, muscle tone, and reflex activity correlated well with one another; heart rate correlated less well; and color the least. Our data confirms the limited use of the Apgar score in preterm infants and demonstrates the different responses of the Apgar score's components.