Extreme immaturity: outcome of 568 pregnancies of 23-26 weeks' gestation.

OBJECTIVE: To provide guidelines to the perinatologist regarding extremely premature infants based on the experience of the University of Toronto Newborn Service (two high-risk perinatal units and one outborn neonatal intensive care unit), with a catchment area of 60,000 deliveries annually. METHODS: The study included all births or admissions in the Newborn Service from January 1, 1982 to June 30, 1987 with gestational age determined by the best obstetric estimate of gestational age, ranging from 23-26 completed weeks. The obstetric records were reviewed and the surviving infants followed prospectively for a minimum of 2 years after delivery. RESULTS: Analysis of the neonatal and 2-year follow-up data on 568 infants born between 23-26 weeks' gestation revealed a 39% mortality rate, which increased with decreasing gestation. The highest mortality rates occurred following complicated pregnancies, including fetal growth restriction. Intact survival increased with increasing gestational age, from 11% at 23 weeks to 50% at 26 weeks. There was a marked improvement in both mortality and morbidity by 25 completed weeks. CONCLUSIONS: The results suggest that an aggressive approach before 24 completed weeks' gestation is not warranted. From a total of 60,000 live births per year, only one child born at 23 weeks' gestation and three at 24 weeks were free of major handicap at 2 years.

Long-term growth in small-for-date children.

The growth patterns of 158 infants with significant intrauterine growth retardation (IUGR) were studied for the first 2 years of life. Eighty-four infants were born after 36 completed weeks. All these full-term infants survived; complete follow-up data were obtained for 78. Acceleration of growth in weight began soon after birth and continued for an average of 6 months. Acceleration of linear growth began somewhat later, but was limited to the first 9 months. Twenty-three infants (29%) were still below the 5th centile for both weight and height by 2 years of age. There was a negative correlation between the neonatal ponderal index and length at 18 months for females only. Seventy-four infants were born prematurely, before 37 weeks' gestation. Mortality in this group was 18% and complete follow-up data were obtained for 49 of the 61 survivors. Birth weight was regained on average at 11 days; accelerated weight velocity began 4-6 weeks before the expected date of delivery (term date). The potential for catch-up growth lasted up to 9 months after the term date. By 18 months, however, 44% of these pre-term infants were still below the 5th centile for weight. Size at 18 months post-term was correlated with weight at the term date and length at 3 months post-term, but not with the degree of IUGR or with the ponderal index.

Is chronic lung disease in low birth weight infants preventable? A survey of eight centers.

Chronic lung disease in prematurely born infants, defined as the need for increased inspired oxygen at 28 days of age, was thought to be more common in some institutions than in others. To test this hypothesis, we surveyed the experience in the intensive care nurseries at Columbia and Vanderbilt Universities, the Universities of Texas at Dallas, Washington at Seattle, and California at San Francisco, the Brigham and Women's Hospital in Boston, Texas Children's Hospital in Houston, and Mt Sinai Hospital in Toronto. The survey included 1,625 infants with birth weights of 700 to 1,500 g. We confirmed the relationship of risk to low birth weight, white race, and male sex. Significant differences in the incidence of chronic lung disease were found between institutions even when birth weight, race, and sex were taken into consideration through a multivariate logistic regression analysis. Columbia had one of the best outcomes for low birth weight infants and the lowest incidence of chronic lung disease.

Issues in early identification of hearing loss.

In a general hospital, an early detection research program based on a high risk register and brain stem electric response audiometry (BERA) using click and frequency-specific stimuli identified 631 at-risk neonates from the well baby nursery and the neonatal intensive care nursery (ICN). BERA tests were done before discharge and four months later; comparison of outcomes revealed substantial discrepancies. From the follow-up test, 51 cases of mild to severe hearing loss were identified. Experience from the research program has raised some issues relevant for establishment of service programs. Evaluation of all babies (general nursery and ICN) is justified on the basis of yield but is resource consuming; strategies for minimizing work load are discussed. Risk factor criterion levels affect case loading and yield. Frequency-specific BERA identifies cases which would not be detected by click stimuli and which raise management questions. Deferral of testing to four months is feasible and desirable.

Effect of neonatal complications in premature infants on early parent-infant interactions.

A total of 184 infants in a neonatal intensive care unit with birthweights less than 1501 g were rated daily on a Morbidity Scale covering the 20 most common diseases and pathophysiological states in neonatology, the severity of each condition being rated on a scale of 0 to 3. To measure the impact of various degrees of complications on parental caretaking style, 20 infants with serious medical complications were paired with 20 infants who had a comparatively easy medical course. Both groups were observed during maternal visits to the hospital and again during a feeding three months after discharge home. Sick infants showed significantly less motor movements when ill but after recovery were similar to well infants of the same age. Parents visiting sick infants interacted far less with their infants than did parents of well babies, and this continued after recovery. It also persisted at home two months after the expected date of delivery. In addition, mothers whose infants had been seriously ill for less than 17 days interacted with them significantly more than mothers whose babies had been ill for over 35 days. While maternal background variables predicted the level of maternal activity with the comparatively well infants and those with short illnesses, they did not do so in the group of infants with long illnesses.

The prognostic value of computed tomography of the brain in asphyxiated premature infants.

Computed tomography brain scans were done during the first two weeks of life in 145 asphyxiated or apneic newborn infants with birth weights less than 1,500 gm. Sixty-two survived and were assessed neurodevelopmentally at 18 months from the term date. Follow-up CT scans were done at six months post term. There were major neurodevelopmental defects in 15 children, minor defects in 10, and no gross abnormalities in 37. The neonatal CT scans showed germinal layer hemorrhage in 45 (73%) of the survivors and was combined with ventricular bleeding in 29 cases (47%). Areas of hypodensity of brain tissue were present in all neonatal CT and were extensive in 84%. Ventricular dilatation occurred in 31%. There was a significant relationship between hydrocephalus and CT findings of IVH and dilated ventricles, but no relationship between outcome at 18 months and any other features of the neonatal CT. Only four of 56 CT scans done at six months post term were normal. Dilatation of the ventricles and subarachnoid spaces was common but was not related to subsequent neurodevelopmental status.

Is intensive care justified for infants weighing less than 801 gm at birth?

During 1974-1977, 158 infants of birth weights less than 801 gm were referred from outlying hospitals. The survival rate was 25% for the whole group and 35% for those weighing 700 to 800 gm. Many were in a poor condition on arrival. One hundred and nineteen died. The most common causes of death were intracranial hemorrhage (39), RDS (26), and infection (13). Thirty-seven of the 39 survivors were followed until 18 months postterm. Growth failure was common--57% were below the third percentile in weight, 37% in length, and 17% in head circumference. Three had retrolental fibroplasia. Five children (14%) had major neurologic sequelae. Eight were severely handicapped with a Bayley score of less than 70 and ten were moderately handicapped with a Bayley score between 70 and 84, resulting in a neurodevelopmental handicap rate of 49%. Significant factors correlating with survival and intact outcome were birth weight greater than or equal to 700 gm, gestation greater than or equal to 26 weeks, the absence of asphyxia, and good condition on arrival at the NICU. There was no intact survival below 700 gm birth weight. The handicap rate of survivors between 700 and 800 gm was only 39%. Although intensive care in a referral unit may not be justified for those less than 700 gm, every effort should be made in the care of those 700 to 800 gm.

The prognostic value of computed tomography as an adjunct to assessment of the term infant with postasphyxial encephalopathy.

Prospective follow-up studies were done on 62 term infants who were treated as neonates for clinical evidence of postasphyxial encephalopathy. Computed tomographic studies were done during the first two weeks of life and repeated at six months of age. All children were followed a minimum of 18 months, at which time they underwent a psychometric and a neurologic evaluation. Major neurodevelopmental sequelae consisted of: hydrocephalus; spastic quadriplegia, hemiplegia, or diplegia; or a mean Bayley score less than 70. Major sequelae were present in 29 (47%) of the children: all were severely handicapped. Five other children scored between 70 and 85 on the Bayley test. Computed tomographic scans were highly predictive of status at 18 months. Eleven of the 15 with intraventricular or parenchymal hemorrhage were severely handicapped. Eighteen of 20 with extensive areas of hypodensity of the white and gray matter (neonatal CT) were abnormal at 18 months. All but two were severely handicapped. The results suggest that CT studies are very useful in the care of the asphyxiated term infant who has clinical signs of encephalopathy.

Growth and development in children recovering from bronchopulmonary dysplasia.

Of 26 patients with bronchopulmonary dysplasia, 20 (77%) survived and were followed prospectively for two years post-term. Lower respiratory tract infections occurred in 17 of the 20 children (85%), and required hospitalization in ten (50%) during the first and in four (20%) during the second year. At two years post-term only two patients had significant respiratory symptoms at rest, but 78% had residual radiographic changes. The average weight and height at term were at or below the third percentile. Growth occurred at an accelerated rate with improvement of respiratory symptoms, with average weight reaching the third to tenth percentile for both sexes, and tenth to twenty-fifth percentile for height in the boys and the twenty-fifth percentile for the girls by two years post-term. Growth retardation was associated with severe and prolonged respiratory dysfunction. Fifteen (75%) were free of major developmental defects. Five had mean Bayley scores less than 85 at 18 months post-term; one also had hydrocephalus. Developmental outcome seems related to perinatal and neonatal events rather than to the presence or absence of BPD.

Correlation between computed tomography and autopsy in premature and full-term neonates that have suffered perinatal asphyxia.

The findings at autopsy were correlated with the computed tomographic (CT) diagnosis in 90 neonates that had suffered perinatal hypoxia and had CT within 10 days before autopsy. CT was accurate in the diagnosis of supratentorial hemorrhage whether it was subependymal, intraventricular, or intracerebral. Infratentorial hemorrhage was difficult to detect or localize with accuracy. Correlation between areas of hypodense brain tissue seen on CT and areas of ischemic brain damage other than hemorrhage at autopsy was poor. Diagnosis of generalized cerebral edema by CT, however, was very good.

Peripheral median nerve damage secondary to brachial arterial blood gas sampling.

Examination at 18 months post-term of 139 infants of birth weight less than or equal to 1,500 gm revealed 18 instances (13%) of persistent median nerve damage. All affected infants had received frequent percutaneous brachial artery punctures as neonates. Block sections of the cubital fossa done at autopsy on 12 randomly selected very low-birth-weight infants showed perineural hemorrhage, and Wallerian degeneration or traumatic neuroma of the median nerve in eight patients. It is recommended that brachial artery punctures be avoided whenever possible in the neonatal period.

The status at two years of low-birth-weight infants born in 1974 with birth weights of less than 1,001 gm.

A two-year follow-up study of 43 infants of birth weight less than or equal to 1,000 gm born during 1974 revealed the following: average height at two years was between the tenth and twenty-fifth percentiles; average weight between the third and tenth percentiles. Fifteen (35%) developed lower respiratory tract infections during the first two years. Seven (16%) had retrolental fibroplasia. Major neurologic defects occurred in four (9%); severe developmental delay (mean developmental quotient less than 80) was found in nine others (21%). Defects of the central nervous system were closely associated with a neonatal history of intracranial hemorrhage or seizures or both.

Present status of the infant of very low birth weight treated in a referral neonatal intensive care unit in 1974.

In 1974, 250 infants with birth weights of 1500 g or less were referred to the Intensive Care Unit at the Hospital for Sick Children, Toronto. Sixty-six per cent survived. Prospective follow-up studies of the survivors have been completed over a minimum of two years. Infants at highest risk for handicapping defects (about 85%) are those who survived intracranial haemorrhage during the neonatal period. Neurological defects encountered in these children were severe--hydrocephalus, spastic quadriplegia, hemiplegia or microcephalus--and were usually associated with low psychometric scoring. The second highest risk group were small for gestational age infants. Of these, 53% were significantly handicapped at two years of age, and 43% had developmental quotients of less than 80. These defects could not be related to postnatal events. The third category at high risk were infants with birth weights of 1000 g or less. Among these, 30% had a significant handicap by two years of age. The outcome in the remainder of the sample was generally good. These results suggest that the decreased mortality of the very premature infant is associated with an increased number of relatively normal survivors and that the infants at highest risk for subsequent defects can be identified at or shortly after birth.