Search PubMed⌕ Search

Biomedical subjects

J E Tyson

Publications and source records attributed to J E Tyson.

At least 37 records · Page 2Linked to original sources
PubMed1998

A multicenter trial of two dexamethasone regimens in ventilator-dependent premature infants.

BACKGROUND: Ventilator-dependent premature infants are often treated with dexamethasone. However, the optimal timing of therapy is unknown. METHODS: We compared the benefits and hazards of initiating dexamethasone therapy at two weeks of age and at four weeks of age in 371 ventilator-dependent very-low-birth-weight infants (501 to 1500 g) who had respiratory index scores (mean airway pressure x the fraction of inspired oxygen) of 52.4 at two weeks of age. One hundred eighty-two infants received dexamethasone for two weeks followed by placebo for two weeks, and 189 infants received placebo for two weeks followed by either dexamethasone (those with a respiratory-index score of > or =2.4 on treatment day 14) or additional placebo for two weeks. Dexamethasone was given at a dose of 0.25 mg per kilogram of body weight twice daily intravenously or orally for five days, and the dose was then tapered. RESULTS: The median time to ventilator independence was 36 days in the dexamethasone-placebo group and 37 days in the placebo-dexamethasone group. The incidences of chronic lung disease (defined as the need for oxygen supplementation at 36 weeks' postconceptional age) were 66 percent and 67 percent, respectively. Dexamethasone was associated with an increased incidence of nosocomial bacteremia (relative risk, 1.5; 95 percent confidence interval, 1.1 to 2.1) and hyperglycemia (relative risk, 1.9; 95 percent confidence interval, 1.2 to 3.0) in the dexamethasone-placebo group, elevated blood pressure (relative risk, 2.9; 95 percent confidence interval, 1.2 to 6.9) in the placebo-dexamethasone group, and diminished weight gain and head growth (P< 0.001) in both groups. CONCLUSIONS: Treatment of ventilator-dependent premature infants with dexamethasone at two weeks of age is more hazardous and no more beneficial than treatment at four weeks of ages.

Age Factors↗
PubMed1998

Very low birth weight outcomes of the National Institute of Child Health and Human Development Neonatal Research Network, January 1993 through December 1994.

OBJECTIVES: Our purpose was to determine the mortality and morbidity rates for infants weighing 501 to 1500 g according to gestational age, birth weight, and gender. STUDY DESIGN: Perinatal data were collected prospectively on an inborn cohort from January 1993 through December 1994 by 12 participating centers of the National Institute of Child Health and Human Development Neonatal Research Network and were compared with the corresponding data from previous reports. Sociodemographic factors, perinatal events, and the neonatal course to 120 days of life, discharge, or death were evaluated. RESULTS: Eighty-three percent of infants survived until discharge to home or to a long- term care facility (compared with 74% in 1988). Survival to discharge was 49% for infants weighing 501 to 750 g at birth, 85% for those 751 to 1000 g, 93% for those 1001 to 1250 g, and 96% for those 1251 to 1500 g. The majority of deaths occurred within the first 3 days of life. Mortality rates were greater for male than for female infants. Respiratory distress syndrome was the most frequent pulmonary disease (52%). Chronic lung disease (defined as an oxygen requirement at 36 weeks after conception) developed in 19%. Thirty-two percent of infants had evidence of intracranial hemorrhage. Periventricular leukomalacia was noted in 6% of infants who had ultrasonography after 2 weeks. The average duration of hospitalization for survivors was 68 days (122 days for surviving infants weighing 501 to 750 g, compared with an average of 43 days for surviving infants 1251 to 1500 g). Among infants who died, the average length of stay was 19 days. CONCLUSIONS: The mortality rate for infants weighing between 501 and 1500 g at birth continues to decline. This increase in survival is not accompanied by an increase in medical morbidity. There are interactions between birth weight, gestational age, sex, and survival rates.

Adolescent↗
PubMed1998

Outcomes of very low birth weight twins cared for in the National Institute of Child Health and Human Development Neonatal Research Network's intensive care units.

OBJECTIVE: The study's aim was to compare outcomes of very low birth weight twins with those of matched singletons. STUDY DESIGN: With data from the Neonatal Research Network registry (May 1991 to December 1994), univariable and multivariable comparisons of very low birth weight twin pairs and singletons were performed in 2 subgroups: (1) all paired twins and singletons with birth weights between 401 and 1500 g and (2) all paired twins and singletons born at <28 weeks' gestation. RESULTS: Twins constituted 19% of infants admitted with very low birth weight. Mothers of twins were more likely to receive prenatal care, have labor, have cesarean delivery, and receive antenatal glucocorticoids. Twins were more likely to have respiratory disease and to receive surfactant. Second-born twins had more early respiratory disease but similar longer-term outcomes. The risks of death, chronic lung disease, and grade III or IV intracranial hemorrhage were similar in twins and singletons. CONCLUSIONS: Although very low birth weight twins compose a sizable proportion of admissions, in National Institute of Child Health and Human Development Neonatal Research Network intensive care units, twins and singletons have similar outcomes.

Birth Weight↗
PubMed1998

Conventional consent with opting in versus simplified consent with opting out: an exploratory trial for studies that do not increase patient risk.

OBJECTIVE: The objective of this study was to assess a modified consent procedure allowed under federal regulations and developed for studies, particularly clinical trials, that are judged by the Institutional Review Board to reduce or have no effect on patient risk. STUDY DESIGN: This was a randomized trial of a conventional consent procedure that required parental signature to give consent (opting in) after a comprehensive disclosure of the rights of participants in research versus a modified consent procedure that required parental signature to refuse consent (opting out) after specific disclosures appropriate when risk is not increased. Consent was sought for a trial of primary follow-up care for disadvantaged infants at high risk, a trial judged by our Institutional Review Board to increase access to care for both groups. A blinded assessor interviewed mothers within 24 hours of the consent decision. RESULTS: Among the 44 mothers interviewed, the modified consent group scored higher than the conventional consent group in recall and understanding of study purpose and methods (47% vs 30%; p < 0.02). Other comparisons provided no evidence that the modified consent procedure was less desirable. Virtually all mothers reported satisfaction. CONCLUSIONS: The modified approach may improve communication and facilitate studies judged by the Institutional Review Board to be risk-neutral or risk-reducing. Further evaluation of a modified consent procedure for such studies is warranted.

Adult↗
PubMed1998

Incidence, presenting features, risk factors and significance of late onset septicemia in very low birth weight infants. The National Institute of Child Health and Human Development Neonatal Research Network.

BACKGROUND: Septicemia is a major antecedent of morbidity and mortality in very low birth weight (501- to 1500-g) infants. Our purpose was to determine prospectively the incidence, clinical presentation, laboratory features, risk factors, morbidity and mortality associated with late onset septicemia in infants 501 to 1500 g. METHODS: Clinical data were prospectively collected for 2416 infants enrolled in a multicenter trial to determine the efficacy of intravenous immunoglobulin in preventing nosocomial infections. Septicemia was confirmed by positive blood culture in 395 symptomatic infants. Multivariate analyses of factors associated with septicemia were performed. RESULTS: Sixteen percent of VLBW infants developed septicemia at a median age of 17 days. Factors associated with septicemia by logistic regression included male gender, lower gestational age and birth weight and decreased baseline serum IgG concentrations. Increasing apnea (55%), feeding intolerance, abdominal distension or guaiac-positive stools (43%), increased respiratory support (29%), lethargy and hypotonia (23%) were the dominant presenting features of septicemia. An abnormal white blood cell count (46%), unexplained metabolic acidosis (11%) and hyperglycemia (10%) were the most common laboratory indicators. Septicemic infants, compared with nonsepticemic infants, had significantly increased mortality (21% vs. 9%), longer hospital stay (98 vs. 58 days) and more serious morbidity, including severe intraventricular hemorrhage, bronchopulmonary dysplasia and increased ventilator days (P < 0.001). CONCLUSIONS: Late onset septicemia is common in very low birth weight infants, and the rate is inversely proportional to gestational age and birth weight. Septicemia is more common in males and those with low initial serum IgG values. A set of clinical signs (apnea, bradycardia, etc.) and laboratory values (leukocytosis, immature white blood cells and neutropenia) increase the probability of late onset sepsis, but they have poor positive predictive value.

Female↗
PubMed1997

Vitamin A to prevent bronchopulmonary dysplasia in very-low-birth-weight infants: has the dose been too low? The NICHD Neonatal Research Network.

OBJECTIVE: Inconsistent effects of vitamin A supplementation on prevention of bronchopulmonary dysplasia have been reported. Meta-analysis of these reports resulted in a relative risk of 0.69-1.02 for death or bronchopulmonary dysplasia associated with vitamin A supplementation. Effective dosage regimens or serum retinol concentrations have not been determined in previous reports. The purpose of this pilot study was to define a vitamin A regimen that produces serum retinol concentrations of 25-55 micrograms/dl. STUDY DESIGN: In this three-phase study, 91 infants (mean birth weight 799-864 g) were enrolled. Vitamin A was administered three times/week for 4 weeks at an average daily dose of 986-2143 IU/day. Physical examinations were performed and serum retinol specimens were collected weekly to assess clinical signs of toxicity. RESULTS: The majority of serum retinol concentrations remained < 25 micrograms/dl until an intramuscular vitamin A dose of 5000 IU/dose three times/week was used. No clinical signs of toxicity were associated with the higher dosage and higher serum concentrations of vitamin A. CONCLUSION: A large clinical trial of vitamin A supplementation with 5000 IU/dose three times/week (25-114% more than the dose used in the three published clinical trials) is needed to assess whether vitamin A supplementation safely reduces the risk of bronchopulmonary dysplasia in very-low-birth-weight infants.

Adrenal Cortex Hormones↗
PubMed1997

Emergency room visits despite the availability of primary care: a study of high risk inner city infants.

Very low birth weight preterm infants randomized to receive comprehensive primary care in an ongoing clinical trial were prospectively evaluated to determine the cause of frequent emergency room use despite the availability of a primary healthcare provider and specific social services. Mothers were interviewed to assess knowledge of available resources, when to seek medical attention, and the perception of problems that limit access to health care. The healthcare provider was not called before 49% of the emergency room visits and mothers often did not recall what infant signs needed medical attention. Seventy-nine percent of emergency room visits were delayed more than 10 hours; and 15 of 62 (24%) emergency room visits resulted in admittance to the hospital. We conclude that in high-risk populations, the mere availability of primary care does not assure that it will be used. New strategies to help parents know when and how to use services are needed to increase the delivery of primary care.

Emergency Medical Services↗
PubMed1997

Light reduction and the electroretinogram of preterm infants.

AIMS: To examine the effects of light on retinal development and function in preterm infants as measured by the electroretinogram (ERG). Secondary outcomes included visual acuity testing, the incidence of retinopathy of prematurity, and general wellbeing, reflected in feeding tolerance, rate of weight gain, and length of hospital stay. METHODS: Eligibility criteria for enrollment were birthweight < or = 1250 g and gestational age < or = 31 weeks. Sixty one infants were randomly allocated by 6 hours after birth to a control or treatment group which wore 97% light filtering goggles for a minimum of four weeks or until the infant reached 31 weeks postmenstrual age. RESULTS: There were no significant differences between the two groups in the numbers of electroretinograms performed at 36 weeks of postmenstrual age. Although the sample size was not large enough to exclude clinically important differences in secondary outcomes, no significant differences were observed between the groups in visual acuity testing at 4-6 months corrected age, incidence of retinopathy of prematurity, weight gain, or length of stay. CONCLUSION: These data support the safety and feasibility of this intervention. A much larger study will be needed to determine whether light reduction to the eyes of very low birthweight infants will reduce the incidence of retinopathy of prematurity or enhance general well-being.

Electroretinography↗
PubMed1997

Have Medicaid reimbursements been a credible measure of the cost of pediatric care?

OBJECTIVE: Despite uncertain validity as a measure of cost, Medicaid reimbursements may be used to compare the costs of different pediatric interventions. We explored the credibility of Medicaid reimbursements as a measure of the costs of inpatient care associated with two different approaches to follow-up care for high-risk indigent infants. DESIGN: Analysis of Medicaid reimbursements within a randomized trial of primary follow-up care. PATIENTS: Infants </=1500 g at birth in a large county hospital (Parkland Memorial Hospital). INTERVENTION: Conventional care after nursery discharge (with well-baby care and care for chronic illnesses provided in our follow-up clinic) or primary care (with care for acute illnesses also provided in the follow-up clinic). Measures to prevent a lapse in Medicaid coverage were included in all clinic visits. OUTCOME MEASURES: The completeness, comparability, and plausibility of Medicaid reimbursements for inpatient care of the two groups between nursery discharge and 1 year adjusted age. RESULTS: A high percentage (90% to 91%) of both groups were enrolled in Medicaid. However, with fewer clinic visits in the conventional care group, Medicaid coverage often lapsed in this group, particularly among the highest risk infants. As a result, the proportion of hospital days reimbursed by Medicaid was substantially lower for conventional care than primary care infants (53% [92/174] vs 96% [298/310]). An even larger disparity was observed for pediatric intensive care days (10% [6/61] vs 100% [33/33]). Implausible Medicaid reimbursements included a lower reimbursement rate per day in the pediatric intensive care unit than on the pediatric floor (1 infant), a lower reimbursement rate per day for hospital care than home care (1 infant), and a mean reimbursement rate per day for our private pediatric teaching hospital ($1244/day) that did not exceed that for the private nonteaching pediatric hospital ($1268/day). The reimbursement rate for our public teaching hospital was particularly low ($507/day) despite a high acuity of illness (21% of hospital days in the pediatric intensive care unit). CONCLUSIONS: Without proper validation, reimbursements from Medicaid (or any program that replaces it) should not be assumed to provide an unbiased or acceptably accurate measure of the relative or absolute cost of pediatric health care interventions.

Continuity of Patient Care↗
PubMed1996

Viability, morbidity, and resource use among newborns of 501- to 800-g birth weight. National Institute of Child Health and Human Development Neonatal Research Network.

OBJECTIVES: To assess risk factors affecting viability and analyze the effects of mechanical ventilation (MV) on neonatal outcome and resource use among extremely premature infants. DESIGN: Inception cohort study. SETTING: Neonatal intensive care units of the 12-center National Institute of Child Health and Human Development Neonatal Research Network. PARTICIPANTS: A total of 1126 infants with a birth weight of 501 to 800 g born in network centers between January 1, 1994, and December 31, 1995. MAIN OUTCOME MEASURES: Observed survival; maximum estimated survival (assuming the same survival among infants who died without MV as among infants in the same risk category who received MV); observed and maximum estimated survival without severe brain injury (either interventricular echodensity with ventricular dilation or parenchymal echodensity); hospital stay; resource investment. RESULTS: Overall mortality was 43%; mortality in infants without MV was 93%. A total of 15% of all the infants died without MV. Females, small-for-gestational-age infants, and infants whose mothers received antenatal steroids had an advantage in survival with MV equivalent to an increase in birth weight of 90 g, 57 g, and 67 g, respectively. The corresponding advantage of these infants in survival without severe brain injury was 107 g, 97 g, and 64 g, respectively. Females in the lowest birth-weight group were more likely to die without MV than were larger males with a similar estimated likelihood of survival with MV. Mean hospital stay was 115 days for the survivors, values much greater than the 17.9-day standard for 501- to 800-g survivors under the diagnosis related group system. Resource investment was considerable (127 hospital days per survivor and 148 days per survivor without severe brain injury), but, like outcome, varied markedly between risk categories. Had MV been used for all infants who died, we estimate a substantial increase in resource use and a maximum of 8 additional survivors (no more than 6 without severe brain injury per 100 infants with a birth weight of 501 to 800 g. CONCLUSIONS: Although recommendations to initiate or forgo MV for extremely premature infants have often focused on 1 factor (birth weight or gestational age), multiple factors should be considered. Other factors being equal, our analyses support use of MV for females at a minimum birth weight approximately 100 g lower than that for males. The current diagnosis related group reimbursement system can be expected to compromise resources for 501- to 800-g infants who would benefit from MV. Such care entails considerable resource use, although the cost per life-year gained is likely to be considerably less than that for many adults given intensive care. Our findings can be used to facilitate more appropriate treatment decisions, determine adequate resources, and better inform the debate about the benefits and burdens of intensive care for extremely premature newborns.

Brain Injuries↗
PubMed1996

Late-onset sepsis in very low birth weight neonates: a report from the National Institute of Child Health and Human Development Neonatal Research Network.

OBJECTIVE: Late-onset sepsis (occurring after 3 days of age) is an important problem in very low birth weight (VLBW) infants. To determine the current incidence of late-onset sepsis, risk factors for disease, and the impact of late-onset sepsis on subsequent hospital course, we evaluated a cohort of 7861 VLBW (401 to 1500 gm) neonates admitted to the 12 National Institute of Child Health and Human Development (NICHD) Neonatal Research Network centers during a 32-month period (1991 to 1993). METHODS: The NICHD Neonatal Research Network maintains a prospectively collected registry of all VLBW neonates cared for at participating centers. Data from this registry were analyzed retrospectively. RESULTS: Of 6911 infants who survived beyond 3 days, 1696 (25%) had one or more episodes of blood culture-proven sepsis. The vast majority of infection (73%) were caused by gram-positive organisms, with coagulase-negative staphylococci accounting for 55% of all infections. Rate of infection was inversely related to birth weight and gestational age. Complications of prematurity associated with an increased rate of infection included intubation, respiratory distress syndrome, prolonged ventilation, bronchopulmonary dysplasia, patent ductus arteriosus, severe intraventricular hemorrhage, and necrotizing enterocolitis. Among infants with bronchopulmonary dysplasia, those with late-onset sepsis had a significantly longer duration of mechanical ventilation (45 vs 33 days; p <0.01). Late-onset sepsis prolonged hospital stay: the mean number of days in the hospital for VLBW neonates with and without late-onset sepsis was 86 and 61 days, respectively (p <0.001). Even after adjustment for other complications of prematurity, including intraventricular hemorrhage, necrotizing enterocolitis, and bronchopulmonary dysplasia, infants with late-onset sepsis had a significantly longer hospitalization (p <0.001). Moreover, neonates in whom late-onset sepsis developed were significantly more likely to die than those who were uninfected (17% vs 7%; p <0.000 1), especially if they were infected with gram-negative organisms (40%) or fungi (28%). Deaths attributed to infection increased with increasing chronologic age. Whereas only 4% of deaths in the first 3 days of life were attributed to infection, 45% of deaths after 2 weeks were related to infection. CONCLUSIONS: Late-onset sepsis is a frequent and important problem among VLBW preterm infants. Successful strategies to decrease late-onset sepsis should decrease VLBW mortality rates, shorten hospital stay, and reduce costs.

Age of Onset↗
PubMed1996

Early-onset sepsis in very low birth weight neonates: a report from the National Institute of Child Health and Human Development Neonatal Research Network.

OBJECTIVE: Early-onset sepsis (occurring within 72 hours of birth) is included in the differential diagnosis of most very low birth weight (VLBW) neonates. To determine the current incidence of early-onset sepsis, risk factors for disease, and the impact of early-onset sepsis on subsequent hospital course, we studied a cohort of 7861 VLBW neonates (401 to 1500 gm) admitted to the 12 National Institute of Child Health and Human Development (NICHD) Neonatal Research Network centers during a 32-month period (1991-1993). METHODS: The NICHD Neonatal Research Network maintains a prospectively collected registry on all VLBW neonates born or cared for at participating centers. Data from this registry were analyzed retrospectively. RESULTS: Blood culture-proven early-onset sepsis was uncommon, occurring in only 1.9% of VLBW neonates. Group B streptococcus was the most frequent pathogen associated with early-onset sepsis (31%), followed by Escherichia coli (16%) and Haemophilus influenzae (12%). Decreasing gestational age was associated with increased rates of infection. Antibiotic therapy for suspected sepsis is frequently initiated at birth in VLBW neonates. Almost half of the infants in this cohort were considered to have clinical sepsis and continued to receive antibiotics for 5 or more days, despite a negative blood culture result in 98% of cases. These findings underscore the difficulty of ruling out sepsis in the symptomatic immature neonate and the special concern for culture-negative clinical sepsis in the face of maternal antibiotic use. Neonates with early-onset sepsis were significantly more likely to have subsequent comorbidities, including severe intraventricular hemorrhage, patent ductus arteriosus, and prolonged assisted ventilation. Although 26% of VLBW neonates with early-onset sepsis died, only 4% of the 950 deaths that occurred in the first 72 hours of life were attributed to infection. For those infants discharged alive, early-onset sepsis was associated with a significantly prolonged hospital stay (86 vs 69 days; p <0.02). CONCLUSIONS: Early-onset sepsis remains an important but uncommon problem among VLBW preterm infants. Improved diagnostic strategies are needed to enable the clinician to distinguish between the infected and the uninfected VLBW neonate with symptoms and to target continued antibiotic therapy to those who are truly infected.

Age of Onset↗
PubMed1996

Interlaboratory variability of bilirubin measurements.

During an 8-month study, 14 laboratories used automated analytical systems to measure total bilirubin concentrations in lyophilized bovine specimens containing 38, 169, and 253 micromol/L bilirubin (2.2, 9.9, and 14.8 mg/dL, respectively). The measured mean +/- SD (n, range) were: 39 +/- 7 micromol/L (n = 90, 31-53) [2.3 +/- 0.4 mg/dL (1.8-3.1)]; 176 +/- 29 micromol/L (n = 89, 146-222) [10.3 +/- 1.7 mg/dL (8.5-13.0)]; and 260 +/- 43 micromol/L (n = 103, 208-316) [15.2 +/- 2.5 mg/dL (12.1-18.5)]. In comparison with target values, measurements were consistently lower at 4, higher at 6, and within +/- 4% at 4 laboratories for each of the three concentrations. The measured values for each concentration remained fairly constant during the study at each laboratory. We conclude that bilirubin measurements differed significantly from the established target values at most of the participating laboratories.

Animals↗
PubMed1995

Very-low-birth-weight outcomes of the National Institute of Child Health and Human Development Neonatal Network, November 1989 to October 1990.

OBJECTIVE: Our purpose was to describe the neonatal outcomes of 1804 very-low-birth-weight (< or = 1500 gm) infants delivered between November 1989 and October 1990 in the participating centers of the National Institute of Child Health and Human Development Neonatal Research Network. STUDY DESIGN: In an observational study sociodemographic, pregnancy, and delivery data were collected soon after birth, and neonatal and outcome data at discharge, at 120 days, or at death. RESULTS: Maternal and birth weight characteristics included 64% black, 29% white; 71% single mothers; 18% no prenatal care; 17% antenatal steroids; and 12% multiple gestations. Birth weight distributions included 18% weighing 501 to 750 gm, 23% 751 to 1000 gm, 28% 1001 to 1250 gm, and 31% 1251 to 1500 gm. Survival was 39% at < 751 gm birth weight, 77% at 751 to 1000 gm, 90% at 1001 to 1250 gm, and 93% at 1251 to 1500 gm. Survival was 15% to 18% at < or = 23 weeks' gestation, 54% at 24 weeks, 59% at 25 weeks, and 71% at 26 weeks. Surfactant was administered to 45% of the 56% of infants with respiratory distress syndrome. Morbidity, including intraventricular hemorrhage (40%), septicemia (24%), symptomatic patent ductus arteriosus (22%), and necrotizing entercolitis (8%), increased with decreasing birth weight. Oxygen was administered for > or = 28 days to 82% of < 751 gm infants, 49% of 751 to 1000 gm infants, and 10% of > 1001 gm infants. Steroids were administered to 28% of infants who required oxygen for > or = 28 days. Mean hospital stay was 62 days for survivors and 18 days for infants who died. There were large intercenter variations in mortality and morbidity. CONCLUSION: Mortality and morbidity in very-low-birth-weight infants improved in 1989 to 1990 without an increase in morbidity or length of hospital stay. The threshold of the improved survival was > or = 24 weeks and 601 to 700 gm. Although such data are reassuring, the rate of major morbidity in < 1001 gm birth weight infants continues to be high.

Birth Weight↗
PubMed1995

Very-low-birth-weight outcomes of the National Institute of Child Health and Human Development Neonatal Research Network, May 1991 through December 1992.

OBJECTIVES: Our goals were to determine the mortality risk for infants weighing 501 to 1500 gm according to gestational age, birth weight, and gender and to document birth weight-related changes in mortality and morbidity over a 5-year time period. STUDY DESIGN: In this observational study perinatal data were prospectively collected by the 12 participating centers of the National Institute of Child Health and Human Development Neonatal Research Network from May 1991 through December 1992 and compared with the corresponding data from 1987 through 1990. Standard definitions were used to record sociodemographic factors, perinatal events, and the neonatal course to 120 days of life, discharge, or death. RESULTS: The 1991 and 1992 cohort included 4279 in-born infants. Among their mothers 10% were < 18 years old; 55% were black, 31% were white, and 11% were Hispanic; 14% had received no prenatal care; and 20% had received antenatal corticosteroids. Multiple gestations accounted for 20% of the births. Fifty percent of the infants were delivered by cesarean section. During 1991 and 1992 the overall survival for infants weighing 501 to 1500 gm at birth was 81%, compared with 74% in 1987 and 1988. Survival at birth weight 501 to 750 gm was 44%; it was 81% at 751 to 1000 gm, 92% at 1001 to 1250 gm, and 95% between 1251 and 1500 gm. Female infants had a significantly greater chance of surviving than male infants at similar birth weights and gestational ages. At any given gestational age, smaller infants were less likely to survive. Survival in all birth weight categories increased between 1987 and 1992, without accompanying increases in medical morbidity. Major morbidity increased with decreasing birth weight and included late-onset septicemia 22%, chronic lung disease (oxygen dependence at 36 weeks' corrected age) 18%, severe intraventricular hemorrhage (grades III and IV) 11%, and necrotizing enterocolitis 5%. Twelve percent of all infants were treated with corticosteroids for chronic lung disease, including 36% of infants who were oxygen dependent at age 28 days. The mean length of hospital stay was 69 days for survivors and 18 days for infants who died. CONCLUSIONS: Mortality for infants between 501 and 1500 gm at birth has declined over the past 5 years. There are interactions between birth weight, gestational age, gender, and survival rate. This increase in survival was not accompanied by an increase in medical morbidity.

Apgar Score↗