Live-born infants of 24 to 28 weeks' gestation: survival and sequelae at two years of age

The survival rate of infants born alive between 24 and 28 weeks of gestation has increased significantly in this tertiary care centre, from about 9% in the first cohort studied (1966-1970), to 19.5% in the second cohort (1971-1974) and 50.3% in the third cohort (1977-1982); the borderline of practical viability decreased from 27 to 24 weeks over the years of the study. The number of mothers with a history of prior termination of pregnancy increased about sixfold from the second to the third cohorts but the rate of premature births increased by only 50%. The augmented survival rate was accompanied by an increase in the prevalence and total number of children with cerebral palsy, but bilateral blindness due to retinopathy of prematurity and severe sensorineural deafness were reduced. When 96% of children in the third cohort were assessed at two years of age. 13% had severe handicaps, 59% were considered normal and in 24% some handicap was suspected. The serious handicap rate was 28% for children born at 24-26 weeks compared with 8.5% for those born at 27-28 weeks of gestation.

Cognition, school performance, and behavior in very low birth weight and normal birth weight children at 8 years of age: a longitudinal study

Cognition, school performance, and behavior were assessed at 8 years of age in 132 very low birth weight (VLBW) children free of major sensorineural impairments, and the results were contrasted with a randomly selected control group of normal birth weight (NBW) children. Considering their fragile beginnings, the majority of VLBW children were developing normally and were reading and performing in most academic and social areas as well as the NBW children. However, VLBW children were significantly inferior to NBW children on tests of cognition, including tests of intelligence and visual memory, and on teacher's reports of motor skills and initiative. In addition, proportionally more VLBW children (20.5%) than NBW children (5.9%) were reported by their parents to be not coping at school.

The cost of improving the outcome for infants of birthweight 500-999 g in Victoria. The Victorian Infant Collaborative Study Group

The aim of this study was to conduct an economic evaluation of neonatal intensive care for extremely low birthweight (ELBW) infants born in the state of Victoria. Two distinct eras (1979-80 and 1985-87) were compared. Follow-up data at 2 years of age were available for all 89 survivors from the 351 live births in 1979-80, and for 211 of 212 survivors from the 560 live births in 1985-87. The overall cost-effectiveness for ELBW infants during 1985-87 compared with 1979-80 was $104,990 ($A 1987) per additional survivor, or $5390 ($A 1987) per additional life year gained. Cost-effectiveness improved with increasing birthweight. If the quality of life of the survivors was considered, the economic outlook was more favourable. The cost per quality-adjusted life year gained was $5090 ($A 1987), approximately one-tenth of that obtained from the only previous full economic evaluation of neonatal intensive care. Although neonatal intensive care is expensive, it compares favourably with some other health care programmes, particularly as the outcome for ELBW infants continues to improve.

Audiologic assessment of extremely low birth weight infants: a preliminary report

The aim of this study was to assess all relevant aspects of auditory function, including acuity and perception, of a cohort of extremely low birth weight (< 1000 g) children who survived to 8 years of age; 42 of the 59 consecutive survivors born over a 4-year period from January 1, 1977, had a full auditory assessment. Of the 42 children, 4 (9.5%) had a sensorineural hearing impairment, 5 (11.9%) had a conductive hearing impairment, 24 (57.1%) had figure/ground differentiation problems, and 20 (47.6%) had a short-term auditory memory problem. The 4 children with sensorineural hearing impairments had had significantly higher maximum concentrations of bilirubin in the newborn period (median 167 mumol/L vs 138 mumol/L and had required more intensive care; at 8 years of age they were significantly disadvantaged in verbal ability. The 5 children with conductive hearing impairments were not significantly different on any perinatal or other 8-year outcome variables. The proportion with figure/ground differentiation problems (57.1%) was significantly higher than in a normative population (11.7%, chi 2 = 24.2). Extremely low birth weight children with figure/ground differentiation problems were more likely to be restless in the classroom (45.0% [9/20]) than those without these problems (16.7% [2/12]), but the difference was not statistically significant (chi 2 = 2.7). Children with short-term auditory memory problems had significantly higher maximum bilirubin concentrations in the newborn period (median 152 mumol/L vs 137.5 mumol/L). At 8 years of age they had significantly reduced intelligence and reading ability.(ABSTRACT TRUNCATED AT 250 WORDS)

Improvement in outcome for very low birthweight children: apparent or real?

OBJECTIVE

To determine whether improvement in the survival rate of infants with a birthweight of less than 1501 g was accompanied by an increase in the rate of neurological impairment or disability among the survivors.

DESIGN, SETTING AND PATIENTS

Two cohorts of consecutive very low birthweight infants (birthweight less than 1501 g) in one tertiary perinatal centre were followed prospectively to eight years of age; for both cohorts, comparison groups of children of birthweight more than 1501 g were randomly selected from hospital births.

INTERVENTIONS

The first cohort was born before the introduction of assisted ventilation (1966-1970), the second after assisted ventilation was well established (1980-1982).

MAIN OUTCOME MEASURES

Comparisons between cohorts, at eight years of age, of the survival rates and the rates of severe sensorineural impairments and disabilities.

RESULTS

The survival rate for very low birthweight infants to eight years of age almost doubled between these cohorts, from 37.1% to 67.8% (odds ratio [OR], 3.4; 95% confidence interval [CI], 2.5-4.7; chi 2 = 57.6; P much less than 0.0001). The biggest gain was the increase in non-disabled survivors at eight years of age, from 52.6% in the first cohort to 80.8% in the second cohort (OR, 3.5; 95% CI, 2.2-5.7; chi 2 = 26.7; P less than 0.0001). Furthermore, the rate of severe disabilities in survivors fell substantially, from 13.6% to 4.1% (OR, 0.31; 95% CI, 0.14-0.69; chi 2 = 8.3; P less than 0.01). Of specific impairments, the rate of severe sensorineural deafness fell substantially (3.2% to 0%: OR, 0.14, 95% CI, 0.02-0.81; chi 2 = 4.8; P less than 0.05), as did the rate of severe intellectual impairment (13.0% to 2.7%: OR, 0.25; 95% CI, 0.11-0.57; chi 2 = 10.7; P less than 0.002). Only the rate of cerebral palsy increased, but not significantly (2.6% to 6.8%; OR, 2.6; 95% CI, 0.89-7.6; chi 2 = 3.0).

CONCLUSIONS

It has been possible to improve the survival rate of very low birthweight infants over time without increasing the number of severely disabled survivors. Whether the long-term outcome for these infants is continuing to improve with more recent advances in perinatal care remains to be determined.

Is there a lower limit for birth-weight/gestational age and antenatal steroid therapy?

The aim of this study was to determine if there is a lower limit for birth-weight/gestational age below which antenatal steroid therapy may not improve fetal survival. The association between antenatal steroid therapy and survival to 2 years of age was assessed in 2 cohorts of children of birth-weight below 800 g or of gestational ages below 27 weeks. Antenatal steroid therapy was associated with significantly higher survival rates in infants of birth-weight 500-599 g and 700-799 g, and at gestational ages of 25 and 26 weeks. There were few survivors before 25 weeks and none below 500 g birth-weight. After adjustment for extraneous prognostic variables, antenatal steroid therapy was associated overall with approximately a doubling of the survival rates of infants of birth-weight 500-799 g, and of gestational ages 24-26 weeks. In the absence of maternal contraindications, if the goal is to deliver a surviving infant, this study suggests that the obstetrician may assist the survival chances of the tiniest and most immature infants by treating the mother with steroids before birth, with no apparent lower limit of birth-weight or gestational age.

Respiratory health and lung function in 8-year-old children of very low birth weight: a cohort study

In comparison with a cohort of normal birth weight children, those of very low birth weight (less than 1501 g birth weight) had more wheezing illnesses and hospital readmissions for respiratory problems in the first 2 years of life; from 2 years to 8 years of age respiratory health was unrelated to birth weight. Lung function measurements at 8 years of age in very low birth weight children were similar to expected values; few children had severely abnormal lung function. On univariate analyses, forced vital capacity (FVC) and forced expired volume in 1 second (FEV1), but not flow rates, were lower in children who had survived bronchopulmonary dysplasia. However, the univariate analyses were misleading, because bronchopulmonary dysplasia occurred more frequently with lower birth weight, and lower birth weight in turn was strongly related to reduced FVC and FEV1. After adjusting for birth weight and other potential confounding variables, FVC and FEV1 were unrelated to bronchopulmonary dysplasia, and to neonatal ventilation. Flow rates were largely uninfluenced by perinatal events, but were reduced in children with asthma or recurrent bronchitis at 8 years of age. Passive smoking was unrelated to lung function at 8 years of age. However, the effects of passive or active smoking, or perinatal events, on respiratory function or health beyond 8 years of age in very low birth weight survivors remain to be determined.

Changing obstetric practice and 2-year outcome of the fetus of birth weight under 1000 g

The aim of this study was to assess the outcome up to 2 years of age for the fetus of birth weight 500-999 g, over time and in association with changes in obstetric care. Two consecutive cohorts of infants of birth weight 500-999 g were compared from two eras, 1977-1982 and 1985-1987, and their outcome up to 2 years of age was determined with particular emphasis on the effect of various obstetric interventions at the time of birth, such as cesarean delivery, electronic fetal monitoring, antenatal steroid therapy, and tocolytic therapy. The outcome to 2 years was analyzed by logistic function regression to adjust for imbalances in confounding perinatal variables. In the latter era, the survival rate to 2 years increased significantly by almost 50%, and only 7% of the survivors were severely disabled. The rates of delivery by cesarean and of electronic fetal monitoring both increased significantly in the latter era, but neither was associated with the improved outcome. The only variable associated with an improved outcome that was amenable to obstetric intervention at the time of birth was antenatal steroid therapy, which was used equally in both eras. The obstetrician may aid the fetus of birth weight 500-999 g by giving the mother steroids to accelerate fetal lung maturity, but cesarean cannot be recommended as the routine mode of delivery unless there are recognized maternal or fetal indications.

Very low birth weight and growth to age 8 years. I: Weight and height

We determined the heights and weights at ages 2, 5, and 8 years for the following three cohorts of children: group 1 with birth weights between 500 and 999 g; group 2 with birth weights between 1000 and 1499 g; and group 3 with birth weights more than 2500 g. By age 8 years, group 3 children were significantly heavier and taller than all children in groups 1 and 2 combined; group 1 children were significantly shorter than those in group 2, but their weights were similar. From ages 2 to 5 years, annual increments in weight and height were similar in all three groups; however, between ages 5 and 8 years, children in group 3 grew faster than those in groups 1 and 2 combined, and children in group 1 had smaller height increments than those in group 2. Of children with birth weights less than 1500 g, with a weight or height under the 10th percentile at age 2 years, only approximately one half were still below the 10th percentile for the corresponding measurement at age 8 years. Health variables determined before birth, such as maternal height or birth weight ratio, were more important than health after birth in predicting a height or weight below the 10th percentile at age 8 years in children with birth weights less than 1500 g.

Very low birth weight and growth to age 8 years. II: Head dimensions and intelligence

The occipitofrontal circumference was measured in all available children in the following cohorts at ages 2, 5, and 8 years: group 1, consisting of 79 children with birth weight between 500 and 999 g; group 2, with 111 children with birth weight between 1000 and 1499 g; and group 3 with 56 children with birth weight greater than 2500 g; all were white with no signs of moderate or severe cerebral palsy. National Center for Health Statistics reference values indicated substantially more children with an occipitofrontal circumference lower than the 10th percentile, particularly at age 2 years, compared with Nellhaus reference data. Occipitofrontal circumference was the head measurement best correlated with the Full Scale IQ on the Wechsler Intelligence Scale for Children-Revised. Dolichocephaly, often seen in very-low-birth-weight children was unrelated to IQ, and correction of occipitofrontal circumference for dolichocephaly was rarely of clinical importance.

Survivors of extreme prematurity--outcome at 8 years of age

Of 149 infants liveborn in a large maternity hospital in 1980 to 1982 and delivered between 24 and 29 completed weeks of gestation inclusive, 91 (61%) survived; 88 (97%) survivors were assessed at 8 years' corrected age; 77% of children were not disabled; disability was mild in 13%, moderate in 2% and severe in 4% of children. Although survival decreased with decreasing gestation, disability in survivors did not increase. An earlier assessment of the same children at approximately 2 years of age had been unduly pessimistic particularly for those born less than or equal to 26 weeks' gestation. The only other reports in the literature on outcome by gestation have all assessed the children in early childhood, and estimates of severe disability rates from these studies will probably also be too pessimistic. Since the rate of severe disabilities in infants of borderline viability is not much higher than in more mature infants the obstetrician should mainly consider survival chances for the fetus, and not be overly concerned with long-term neurological outcome, when making clinical decisions.

Inguinal hernia in very low birthweight children: a continuing risk to age 8 years

The prevalence of inguinal hernia repair up to 8 years of age was determined in 205 inborn children of birthweight less than 1500 g who had survived to the age of 8 years; 37 (18.0%) of the children required surgery for inguinal hernia, significantly more frequently for boys than girls (32.0% and 3.9% respectively). The cumulative percentage of inguinal hernia operations in boys was 8.7% during primary hospitalization, 20.4% by 2 years, 30.1% by 5 years and 32.0% by 8 years; 36.4% (12 of 33) hernias in boys occurred beyond 2 years of age. The risk of hernia in boys was only marginally higher in those who required assisted ventilation and in those of birthweight less than 1000 g. Very low birthweight infants, particularly boys, are at risk of developing an inguinal hernia not only in infancy but also to at least 8 years of age.

Changing two-year outcome of infants weighing 500 to 999 grams at birth: a hospital study

Survival and neurodevelopmental outcome to 2 years were determined for two cohorts of infants weighing 500 to 999 gm at birth, born in a tertiary maternity hospital. Live births increased over time from an annual average of 48.7 in the first era (January 1977 to March 1982) to 64.6 in the second era (January 1985 to December 1987), largely from referrals of additional mothers with pregnancy complications. In the first era, 33.6% (86/256) of infants survived to 2 years; the survival rate improved significantly to 45.9% (89/194) in era 2. After adjustment for birth weight, the odds ratio for survival in era 2 versus era 1 was 1.39 (95% confidence interval = 1.12, 1.73; p less than 0.01). One known survivor in each era was not seen at 2 years of age. In the first era, 59.3% (51/86) of 2-year-old children were free of disability compared with 68.5% (61/89) in era 2 (NS), but the Mental Development Index of the Bayley Scales improved significantly, from 90.0 in era 1 to 98.0 in era 2. For infants weighing less than 800 gm at birth, not only did the 2-year survival rate improve, adjusted for birth weight (odds ratio = 1.53; 95% confidence interval = 1.06, 2.20; p less than 0.05), but there was also a significant reduction in neurologic disabilities in survivors (p = 0.03). For infants weighing 800 to 999 gm at birth, there was a significant improvement in the survival rate, adjusted for birth weight (odds ratio = 1.37; 95% confidence interval = 1.04, 1.79; p less than 0.05), but the rate of neurologic disabilities was unchanged. Increased survival in our tertiary maternity center was achieved without increasing the annual number of severely disabled 2-year-old survivors.

Outcome to 8 years of infants less than 1000 g birthweight: relationship with neonatal ventilator and oxygen therapy

The study involved a cohort of 59 consecutive survivors with birthweights less than 1000 g, born between 1977 and 1980, to 8 years of age. The aim of the report was to determine if those survivors who had received more oxygen and ventilator therapy differed in their outcome compared with those who had received less oxygen and ventilation. Children were graded into four groups, characterized by decreasing durations of oxygen and ventilation. Children who had received less oxygen and ventilation were more likely to be below the third percentile for weight at 2, 5 and 8 years but the trends were significant only at 2 and 5 years (P = 0.006, P = 0.013 and P = 0.19 respectively). The rate of cerebral palsy was 8% at 8 years; the only children with severe or moderate disabilities from their cerebral palsy were in the lowest oxygen and ventilation group (n = 4, P less than 0.02). The frequency of hospital re-admission and the duration of re-hospitalization did not vary significantly between the four groups at any age. The rates of recurrent wheezing episodes or asthma did not vary significantly between the groups. Although the cohort as a whole had some impairment of lung function compared with healthy full-term controls, there was no significant difference between the four groups. Contrary to expectations, our findings suggest lower rates of poor growth and adverse neurological outcomes with increasing durations of oxygen and ventilation in the newborn period.

Changing diagnosis of cerebral palsy in very low birthweight children

The stability of the diagnosis of cerebral palsy from 2 to 5 years of age was examined in 83 children of birthweight under 1000 gm, and 112 of birthweight 1000 to 1500 gm. In 20 2-year-old children with cerebral palsy, the diagnosis persisted in 11 (55%, 95% confidence intervals 35.1 to 76.9%); 2 of 175 children (1.1%) free of cerebral palsy at 2 years of age subsequently developed the condition. Severe or moderate cerebral palsy at 2 years persisted in all eight children (100%). In 9 of 12 children in whom cerebral palsy at 2 years had disappeared by 5 years, minor neurologic abnormalities and left-hand preference occurred frequently but mean psychologic tests scores were similar to children always free of cerebral palsy. In this cohort, cerebral palsy at 2 years was not a static condition, but overestimated later prevalence.

Methods of delivery and resuscitation of very-low-birthweight infants in Victoria: 1982-1985

This article describes the patterns of delivery and resuscitation for very-low-birthweight infants who were born in Victoria from 1982 to 1985. Caesarean delivery rates increased from 15% to 30% for infants of birthweights of 500-999 g, and from 39% to 52% for infants of birthweights of 1000-1499 g. In level-III hospitals, the proportion of live-born infants who did not receive active resuscitation fell from 32% to 18% for those who weighed 500-999 g, and from 28% to 15% for those who weighed 1000-1499 g. Time trends over the four years showed the management of very-low-birthweight infants to be in a state of rapid transition in all birth settings. At the same time there was a fall in the still-birth rate of infants of birthweights of 500-999 g. Still-births rates for infants of birthweights of 1000-1499 g remained unchanged, as did neonatal mortality rates in both weight groups.

Health and hospital readmissions of very-low-birth-weight and normal-birth-weight children

Rehospitalizations and ongoing health problems at 5 years of age were contrasted between 197 very-low-birth-weight (VLBW) children and 47 normal-birth-weight children. At 5 years of age, the VLBW children had a mean of 1.7 hospital admissions and 8.5 days in a hospital; these means were significantly more than the 0.5 admissions and 1.7 days, respectively, for the normal-birth-weight children. Overall, respiratory tract problems and ear, nose, and throat surgery were the most common reasons for readmissions. Malformations and intensive care sequelae infrequently caused readmissions. No combination of sociodemographic or perinatal variables identified the VLBW children who were destined for hospital readmissions. At 5 years of age, the VLBW children, compared with the normal-birth-weight children, had significantly more ongoing sensorineural problems (29.9% and 10.6%, respectively), ongoing respiratory problems (39.6% and 19.1%, respectively), and other morbidities (31.0% and 17.0%, respectively). The VLBW children, compared with the normal-birth-weight children, had more hospital admissions during the first 5 years of life and more ongoing problems at 5 years of age.

Five-year outcome of infants of birthweight 500 to 1500 grams: relationship with neonatal ultrasound data

Of 154 consecutive survivors of birthweight 500 to 1500 gm, 139 (90.3%) were seen at 5 years of age, corrected for prematurity, and 137 (89%) were able to be fully assessed by both the psychologist and pediatrician. All but two children had had serial cranial ultrasonography with a linear array real-time scanner in the neonatal period. At 5 years, of 39 children with cerebral ultrasound abnormalities detected during their primary hospitalization, seven (17.9%) had cerebral palsy, but 32 (82.1%) did not. A further three children with cerebral palsy at 5 years had had no cerebral abnormalities on ultrasound. Of the cerebral abnormalities diagnosed by ultrasound, ventricular dilation, with or without cerebroventricular hemorrhage, had the highest positive predictive value (40%) for cerebral palsy at 5 years. In the 127 children free from cerebral palsy at 5 years, two (1.6%) had severe intellectual impairment, both of whom had had normal cerebral ultrasonography. Although neonatal cranial ultrasonography with a linear array was somewhat predictive of cerebral palsy at 5 years, the majority of infants with abnormal scans had no severe sensorineural impairments at 5 years.

Selective improvement in cognitive test scores of extremely low birthweight infants aged between 2 and 5 years

The cognitive development at 2 and 5 years of a cohort of extremely low birthweight (ELBW) children (birthweight 500-999 g) was compared with that of cohorts of larger very low birthweight (VLBW) children (birthweight 1000-1500 g) and normal birthweight (NBW) children (birthweight greater than 2500 g) to determine whether the improvements in cognitive function of ELBW infants between 2 and 5 years are apparent or real. At 2 years of age, ELBW children had a mean Mental Developmental Index (MDI) on the Bayley Scales of 90.4, significantly lower than the means of 100.3 for the larger VLBW children (P = 0.006), and 107.8 for the NBW children (P = 0.0002). However by 5 years the mean scores on the Wechsler Preschool and Primary Scales of Intelligence (WPPSI) full-scale for the ELBW and larger VLBW children were virtually identical (105.9 and 106.0 respectively)--but still lower than the mean WPPSI full-scale of 114.6 for the NBW children. After standardizing the MDI and WPPSI scores relative to the NBW children, the ELBW children improved between 2 and 5 years (paired t-test, t = 3.2, P = 0.004) whereas the larger VLBW infants did not. We postulate that ELBW children require more time than larger VLBW children after birth to compensate for perinatal and other stresses, and that developmental delay at 2 years may not always persist to 5 years.

Correction of developmental and intelligence test scores for premature birth

When using tests of infant development and intelligence in children born prematurely, the subject's age is commonly corrected for the degree of prematurity. However, there is disagreement: first, on whether this correction should ever be applied, and second, at what age to discontinue the adjustment. In a theoretical model, the difference between corrected and uncorrected scores in early infancy was massive and the difference remained clinically important until the age of 8.5 years in children who were born extremely prematurely. The clinical implications of using corrected or uncorrected scores were then evaluated in 174 very low birthweight children without severe sensorineural disabilities and with paired Bayley Mental Development Index (MDI) and Wechsler Preschool and Primary Scales of Intelligence (WPPSI) full scale scores. Failure to correct for prematurity reduced the mean MDI by 12.1 points but reduced the mean WPPSI by only 4.1 points. The disparity between individual MDI and WPPSI scores increased significantly with decreasing gestational age if uncorrected scores were used (P = 0.015) but not if scores were corrected. Using corrected scores, the MDI correctly predicted the WPPSI category in 86.1% of children (P less than 0.001) but in only 54.6% using uncorrected scores (the difference was not significant). It is suggested that a practical solution to the dilemma is to correct test scores for prematurity in the age range 2-8.5 years recognizing that only in extremely immature infants will uncorrected scores be substantially lower than corrected ones at a later age.

Increasing the survival of extremely-immature (24- to 28-weeks' gestation) infants--at what cost?

In one tertiary perinatal centre, the advent of positive-pressure assisted ventilation in the 1970s improved the survival of neonates of 24 to 28 completed weeks of gestation. However, the rate of increase in the resources for assisted ventilation and the improvements in survival rates were stepwise and not smooth. Consequently, it has been possible to calculate the cost-effectiveness of neonatal intensive care up to the time of hospital discharge over two separate eras of stable consumption of resources for assisted ventilation. During 1977-1983, to produce one survivor at 24-weeks' gestation compared with one at 28-weeks' gestation consumed 14.4-times the number of patient-days of assisted ventilation, and 4.9-times more of the total nursery resources; the cost-effectiveness of intensive care during this period decreased with decreasing maturity. The over-all cost-effectiveness up to the time of hospital discharge for infants of 24- to 28-weeks' gestation during 1977-1983, compared with 1971-1974, when assisted ventilation was rare, was $62,268 per additional survivor. After 1983, the consumption of resources for assisted ventilation more than doubled in infants of 24- to 28-weeks' gestation. However, there was a diminishing return with respect to the gains in survival during 1984-1986 and the costs per additional survivor averaged $99,574, which was 60% more than were those for 1977-1983. We speculate that to improve survival further in the most-immature infants by increasing resources for assisted ventilation only can be more difficult and more expensive, and even less cost-effective.

Antenatal steroid therapy and 5-year outcome of extremely low birth weight infants

Over a 63-month period beginning January 1, 1977, 258 infants with birth weights of 500-999 g were born alive at one tertiary perinatal center; 170 were offered full intensive care. The mothers of 67 (39.4%) of these 170 infants had been given betamethasone antenatally to accelerate fetal lung maturation. Of the 67 infants exposed to steroids antenatally, 46 (68.7%) survived their primary hospitalization, compared with 43 (41.7%) of the 103 infants who had not been exposed to steroids. This difference is highly significant (chi 2 = 10.7; P less than .005) but is biased because infants in the steroid group had a better prognosis. After adjustment for discrepancies in birth weight and gestational age and other confounding obstetric variables, survival in the steroid group remained substantially higher (relative odds of survival 1.85, 95% confidence intervals 1.16-2.86; P = .006). The improvements in survival were not at the expense of increased rates of chronic ill health or impairments of growth neurodevelopment up to at least 5 years of age. For extremely immature and extremely low birth weight infants, steroids are rarely contraindicated on fetal grounds.

Retinopathy of prematurity in infants of 24-30 weeks' gestational age

Over the 10-year period from January 1, 1977 to December 31, 1986, 1114 infants with gestational ages of 24 to 30 completed weeks were cared for on a long-term basis in our nursery; 757 (68%) infants survived. As expected, both the mortality rate and the prevalence of stage-3 or stage-4 retinopathy of prematurity among survivors fell with increasing maturity at birth (P less than 0.0001). Adjusting for gestational age, and excluding infants with lethal malformations, the mortality rate decreased significantly (P = 0.018) over time by an estimated 11.5%; also the survival rate of infants with at least stage-3 retinopathy of prematurity increased significantly (P = 0.005) by an estimated 6.8%. In other words, for every 10 additional survivors over the decade, six survivors would have been expected to show at least stage-3 retinopathy of prematurity in either eye. Although the prevalence of advanced stages of retinopathy of prematurity increased in immature survivors, it was not in epidemic proportions; however, it was more likely to be related to the survival of the increasing numbers of at-risk immature infants who, in earlier times, would have died.

Growth and very low birth weight

Information on the likelihood of catch up growth in poorly grown very low birthweight children is sparse. The centiles for weight, height, and head circumference were recorded at both 2 and 5 years of age for 135 very low birthweight children and 42 normal birthweight children. At both ages significantly more children of very low birth weight were under the 10th centile for weight and height. Children of birth weight under 1000 g were more often under the 10th centile for weight at 5 years compared with those of birth weight 1000-1500 g. Mean incremental weight gain between 2 and 5 years was significantly less for very low birthweight children. Mean increment in weight from 2 to 5 years was less for very low birthweight children who had been under the 10th centile for weight at 2 years; children who had been under the 10th centile for height also had lower mean height increments. The growth centiles achieved by 2 years of age were useful predictors of poor growth at 5 years, with perinatal data of marginal importance. Only six of 43 (14%) children with a weight at 5 years of age under the 10th centile were small for gestational age at birth. Very low birthweight children who had a weight or height under the 10th centile at 2 years of age usually remained in this category at 5 years with no evidence of catch up growth.

Mortality with increasing assisted ventilation of very-low-birth-weight infants

From Jan 1, 1977, to Jan 1, 1987, very-low-birth-weight (VLBW) infants consumed almost 90% of total patient-days of assisted ventilation of all infants born in one tertiary perinatal center. In the latter five years compared with the first five years, increasing resources allowed proportionately more VLBW infants to be offered assisted ventilation, and the patient-days of assisted ventilation consumed per live birth rose by almost 60%. All VLBW infants did not benefit equally from the increased assisted ventilation. Mortality in infants with birth weights below 1200 g decreased; unexpectedly, mortality in larger VLBW infants (birth weights, 1200 g to 1499 g) rose (relative odds, 3.11; 95% confidence intervals, 1.21 to 7.99). Despite the increased consumption of ventilator resources, there was no substantial impact on overall mortality in VLBW infants.

Increased mortality of preterm infants transferred between tertiary perinatal centres

Over 18 months almost one quarter of infants born before 30 weeks' gestation in a tertiary perinatal centre who required intensive care had to be transferred to other tertiary centres because intensive care facilities were fully occupied. When infants with lethal congenital malformations were excluded half of the 34 infants who were transferred died; this was twice the mortality (24%) in the 111 infants remaining. The difference between the groups was significant (relative odds = 3.1) and remained so after adjustment for any discrepancies in gestational age (relative odds = 4.0). After adjustment for potential confounding variables by logistic function regression the risk of dying for those transferred remained significantly higher than that for infants who remained (relative odds = 4.6, 95% confidence interval 1.8 to 12.1). As the requirement for neonatal intensive care is episodic and unpredictable more flexibility has to be built into the perinatal health care system to enable preterm infants delivered in tertiary perinatal centres to be cared for where they are born.

Muscular strength at 5 years of children with a birthweight under 1500 g

The hand-grip strength was measured as part of the 5-year neurodevelopmental assessment of 24 very low birthweight (VLBW) and 18 normal birthweight (NBW) children. Hand-grip strength was significantly lower in the VLBW children for left and right hands tested individually and for both hands used concurrently. Increasing hand-grip strength was significantly related to 5-year weight percentiles and to being in the NBW group. More of the VLBW children weighed less than the 10th percentile. After adjusting for the 5-year weight percentile, the hand-grip strength of VLBW children was still significantly lower than that for NBW children. This is another aspect of development in which VLBW children are disadvantaged.

The survival of extremely-low-birthweight infants in Victoria: 1982-1985

A population-based survey of mortality in extremely-low-birthweight (500- to 999-g) infants was carried out in Victoria for the years 1982 to 1985. No increase in the number of extremely-preterm births occurred during that time. The still-birth rate fell from 498 still births per 1000 births in 1982-1983 to 403 still births per 1000 births in 1984-1985. The neonatal mortality in 1982-1985 was 638 deaths per 1000 live births, with no significant decline from that of the 1978-1981 cohort. The small increase in neonatal survivors was not associated with any change in the postneonatal death rate. Delivery in a level-3 unit was associated with a significantly better outcome. Multiple births made a major contribution to the extremely-low-birthweight group of infants.

Longitudinal study of very low birthweight infants: intelligence and aspects of school progress at 14 years of age

Consecutive surviving children weighing less than 1501 g when born in 1966-70 were followed prospectively: 87% (146/168) attended normal secondary schools, 4% (7/168) attended schools for those with special needs and 9% (15/168) were untraced. The psychologist assessed 140 children at a mean age of 14.5 years. The mean WISC-R Verbal Score of 89.7 was almost identical to that achieved by the children at 8 years of age (89.2). Thirty three children (24%) had delay in Reading Accuracy on the Neale Analysis of Reading Ability, whilst 66 children (48%) were delayed on the Comprehension Scale. Social class and duration of maternal education were significant predictors of the WISC-R Verbal Scores and Reading Comprehension at 14.5 years but the total variance explained was small. The Bayley Development Index (MDI) available for half of the children at 2 years often underestimated their potential as defined by the WISC-R Verbal Score at 14.5 years. The 8 year intelligence (WISC-R) and reading measures (Neale) were significantly and highly associated with the corresponding measures at 14.5 years. It was concluded that 8 years was an appropriate age to evaluate the outcome of the children and to identify many of those needing educational intervention. The spasmodic nature and sometimes short duration of the help received by many of the children underlines the need for more appropriate intervention for children with learning difficulties.

Mode of delivery of preterm twins

At one high-risk perinatal centre over a 9-year period, 83.1% (103/124) sets of liveborn twins with gestational ages less than 33 weeks were delivered vaginally. Mortality in vaginal births was 26.7% (55/206), almost double that of Caesarean births of 14.3% (6/42), a non-significant difference. When gestational age discrepancies were corrected, however, the trend favouring survival of Caesarean births disappeared. Furthermore, there were no significant associations between mode of delivery and the condition of the infants at birth, or the presence of respiratory distress in the nursery. Because Caesarean section carries substantial risks for the mother our practice of predominantly vaginal deliveries for preterm twins should continue.

Longitudinal study of very low birthweight infants: impairments, health and distance growth to 14 years of age

Of 456 consecutive infants born in a tertiary maternity centre in 1966-70 and of birthweight under 1501 g, 171 (37.5%) survived their primary hospitalization. Subsequently three children died and the outcome of 142 (90.5%) of the remaining children presumably still alive were reviewed at a mean age of 14.5 years. Four children had cerebral palsy although only one child was legally blind, 31.6% (48/152) had an existing or corrected visual impairment; visual impairments occurred significantly more frequently in those of birthweight under 1251 g or those born before 29 weeks gestation. Six children required hearing aids and three others were still epileptic. Four children were chronic asthmatics and one had rheumatoid arthritis. None had disabling malformations and there was no delay in pubertal changes. The distributions of weight, height and head circumference percentiles were not significantly different from a standard Australian population. For children in the cohort, weights and heights were under the 10th percentile in 13.4% and 14.1%, respectively. Of the 30 children with birthweights under the 10th percentile and who were reviewed as teenagers, only eight (26.7%) were still in this weight category.

Extremely-low-birthweight infants: neurological, psychological, growth and health status beyond five years of age

Of 60 consecutive survivors of birth weight 500-999 g, who were born in one tertiary perinatal centre from 1977 to 1980, 59 infants were assessed by a multidisciplinary team at two years of age (corrected for prematurity) and 58 children were evaluated when aged at least five years. At the latter examination, 9% of the 58 children who were assessed were severely disabled; 17% had a mild or moderate disability; and 74% had no important disability. For the 53 children who were tested, the means for the three scales of the Wechsler Preschool and Primary Scales of Intelligence were just above the test mean. The psychologist noted behavioural problems during her assessment in 50% of children, and 29% of mothers reported behavioural problems which could interfere with schooling. At the age of five years and over, five (9%) children had cerebral palsy and one child was deaf. Twenty-two (38%) children had a visual impairment, although only one child was blind; the detection of retinopathy of prematurity in the nursery was an important risk factor. Health problems with readmissions to hospital and suboptimal growth were present in many children at two years of age and frequently these problems persisted to five years of age. Although only four (7%) children were too disabled to attend a normal school, apprehension exists that many of the other children may later encounter educational difficulties. At the two-years' assessment, ascertainment of cerebral palsy had not been complete or entirely accurate and the Mental Developmental Index of the Bayley Scale tended to underestimate the later psychological performance.

Escalating consumption of nursery resources by extremely immature infants

Over a 9-year period at one tertiary perinatal centre there were 59,650 livebirths; although only 1,123 (1.9%) were born at or before 30 weeks' gestation, this small minority of infants consumed 71.7% of total patient-days in the neonatal intensive care unit (NICU) and an inordinate 87.9% of total patient-days of assisted ventilation. Infants born at 24 weeks required 39 times the patient-days of assisted ventilation and 19 times the patient-days in the NICU per survivor compared with those born at 30 weeks' gestation. In infants born before 28 weeks, for each week of decrease in gestation, survivors averaged an extra 13.0 days of assisted ventilation, stayed in the NICU 13.8 days more, and in hospital 14.9 days longer. Any therapy before 28 weeks which can keep infants safely in the uterus could save approximately 2 weeks of nursery resources for each extra intrauterine week and would be beneficial economically, even if it meant hospitalization of the mother over that time.

Children of birth weight less than 1000 g: changing outcome between ages 2 and 5 years

Of 55 consecutive long-term survivors of birth weight 500 to 999 g, complete psychologic and pediatric data were available for 54 children at 2 years corrected age and for 50 at age at least 5 1/2 years. At the latter age, 60% (30 of 50) were not impaired, 10% (five of 50) had severe sensorineural or intellectual impairments, 10% (five of 50) had mild to moderately impairment, and 20% (10 of 50) had minor neurobehavioural abnormalities. Sensorineural deafness in one child and bilateral blindness in one remained stable over time, but of six children with spastic cerebral palsy at 2 years, only three retained this diagnosis at 5 1/2 years. The mean Mental Developmental Index (MDI) on the Bayley Scales at 2 years was 91.1, significantly below the test mean; by 5 1/2 years the mean full scale of the Wechsler Preschool and Primary Scales of Intelligence (WPPSI) was 101.8. The MDI correlated highly with the full-scale WPPSI (r = 0.7), but for individual children it was not always an accurate predictor of 5-year ability. Between 2 and 5 1/2 years there was a substantial reordering within four categories of impairment: findings in 27 children were improved, four were judged to become more severely impaired over time, and 19 did not change. We conclude that our 2-year assessment often underrated the potential of the children as expressed at 5 1/2 years, and that 2 years is too early for reliable classification of children of birth weight 500 to 999 g.

Care of very low birthweight infants with limited neonatal intensive care resources

The advanced technology that is available to treat the tiniest infants has raised the legal and moral dilemma of where and how to distribute limited intensive care resources. In one neonatal intensive care unit it was determined that approximately 80% of its resources over a two-year period were utilized by very low birthweight infants, in spite of the fact that these infants comprised less than 50% of the total admissions to the unit. It was not possible to offer all very low birthweight infants full intensive care; to make this possible, it was calculated that resources would have to increase by 26%. In the present economic climate, and with limited numbers of nurses who are skilled in neonatal intensive care, the prospects for extra resources are poor. What action can or should be taken, legally and morally, when no facilities exist to treat a live-born infant who may possibly benefit from intensive care?

Cerebral palsy in very low birthweight infants surviving to 2 years with modern perinatal intensive care

The rate of cerebral palsy and factors associated with its occurrence were determined in surviving 2-year-old very low birthweight (VLBW) infants born during an era of modern perinatal intensive care. Of the survivors, 12.5% (52/416) of those traced had spastic cerebral palsy. Motor handicaps were mild in 42%, moderate in 25%, and severe in 33% of children with cerebral palsy. The prevalence of cerebral palsy was similar in all birthweight groups up to the upper limit of 1500 gm, and was considerably higher than in survivors born in the same hospital a decade earlier. Although several perinatal variables were associated with the occurrence of cerebral palsy, either singly or in combination, little statistical or clinical confidence would be placed in these associations. Moreover, although 77% of children with cerebral palsy had one or more commonly recognized perinatal risk factors, almost identical rates of risk factors were present in normal children. The advent of cranial ultrasonography during the time of the study was associated with an increase in mortality but no effect on the prevalence of cerebral palsy. Cerebroventricular hemorrhage correlated poorly with the presence of cerebral palsy. The prevalence of cerebral palsy in surviving VLBW infants is unacceptably high; however, no obvious preventable factors in its etiology could be identified.

Improved outcome to two years of very low-birthweight infants: fact or artifact?

In 1966-70, the survival rate for very low-birthweight (VLBW) children born in a tertiary perinatal centre was 37.1 per cent but by 1980-82 it had increased to 68.3 per cent. The latter cohort had a significantly reduced prevalence of strabismus, myopia and a head circumference under the 10th percentile, but a significantly increased prevalence of cerebral palsy compared with the 1966-70 VLBW children. Survivors born in 1980-82 had a significantly increased mean Mental Development Index (MDI) on the Bayley Scales compared with the sub-group of survivors born in 1968-70 but there was also a significant improvement in mean MDI over time for a group of normal-birthweight children. No improvement of MDI scores of VLBW survivors in the 1980-82 cohort could be attributed solely to perinatal care. The two-year-old VLBW children in the 1980-82 cohort had similar rates of sensorineural impairments, disabilities and mean MDI to those who would have survived with the care available in 1966-70. It is concluded that survival of VLBW infants has improved in recent times but that neurodevelopmental outcome still lags behind that of normal-birthweight peers.

Very low birthweight and normal birthweight infants. A comparison of continuing morbidity

One hundred and forty-eight (95.5%) of 155 consecutive two-year survivors of 227 very low birthweight (VLBW, less than 1501 g) infants and 50 (83.3%) of 60 infants of normal birthweight who were selected at random, all of whom were born at the Royal Women's Hospital, Melbourne from October 1980 to March 1982, were seen at the age of two years. Social, psychological and health data were compared between the groups. The mean Bayley Mental Developmental Index scores of VLBW children were significantly lower; the prevalence of major handicaps and poor growth (height and weight below the 10th percentile), and the number of hospital readmissions, wheezing episodes, major and minor congenital anomalies and postnatally-acquired malformations (for example, abnormally shaped skull) were significantly greater in VLBW children. There was a trend for a greater number of episodes of otitis media, lower respiratory tract infections and surgical procedures per child in VLBW children. Extremely low birthweight children (birthweight less than 1000 g) contributed significantly to this morbidity. Parents of VLBW children perceived significantly more problems with infant vomiting and behavioural disturbances at two years of age. The children of mothers of limited education, or immigrant status and non-fee paying or lower socioeconomic families had lower mean Bayley Mental Developmental Index scores but similar handicap rates and health status in both weight cohorts.

Relationship of growth and psychoneurologic status of 2-year-old children of birthweight 500-999 g

There were 257 liveborn infants of birthweight 500-999 g born in one tertiary centre in the 5 1/4 years commencing January 1977; 86 (33.5%) survived to 2 years of age, corrected for prematurity and 83/86 (96.5%) were fully assessed. The prevalence of cerebral palsy was 10/83 (12%) and 17/83 (20%) had a major impairment. The distribution of weights and heights for 2-year-old boys and girls was significantly lower than for the standard population, as was the head circumference distribution for boys; the distribution of the Mental Developmental Index (Bayley Scales) was not related to the head circumference or body weight at two years or to head-circumference/bodyweight or height ratios. At birth measurements of weight, length and head circumference were under the 3rd percentile for 13/86 (15%), 9/86 (10.5%) and 9/86 (10.5%) respectively. By 2 years of age, weight, length and head circumference were under the 3rd percentile in 23/83 (27.7%), 26/83 (31.3%) and 4/83 (4.8%) respectively. 12 children who were SGA at birth were fully assessed at 2 years; the group of 6, who continued with poor postnatal weight gains (under the 3rd percentile) had the highest rate of major impairment but included were the only extremely SGA twins and the only two major malformations in the study. We found no association of other health problems or unfavourable social factors with poor postnatal growth or impaired outcome.

Effects of antenatal steroid therapy on mortality and morbidity in very low birth weight infants

A cohort of 678 consecutive very low birth weight infants, liveborn in one tertiary institution during a 63-month period, was studied to investigate whether antenatal steroid therapy had any beneficial or harmful effects on mortality or morbidity over the first 2 years of life. Comparing the 244 babies who received treatment with the 434 controls, 195 (79.9%) and 265 (61.1%), respectively, were discharged home (P less than 0.001). Mortality in the treated group remained substantially lower and was almost halved after adjustment for birth weight, extreme immaturity, lethal malformations, and confounding obstetric variables (P = 0.001). Fatal cases of respiratory distress syndrome were less common in the treated group (P = 0.044). Of in-hospital survivors, those in the treated group required less positive pressure respiratory support (P = 0.003) and fewer days in oxygen (P = 0.018), and the incidences of bronchopulmonary dysplasia (P = 0.003) and patent ductus arteriosus (P = 0.002) were lower. Two-year survivors who had received treatment were heavier (P = 0.016) and had larger head circumferences (P = 0.029). These beneficial associations in the treated group were not at the expense of increased rates of infection or adverse neurologic outcome. We did not detect any adverse effects of antenatal steroid therapy on any relevant aspect of mortality or morbidity in infancy under circumstances in which the chances of finding substantial differences were high.

Mortality and two year outcome of infants of birthweight 500-1500 g: relationship with neonatal cerebral ultrasound data

Cranial ultrasounds were performed on 218 (96%) of 227 liveborn infants of birthweight 500-1500 g delivered in the Royal Women's Hospital, Melbourne, Australia, in an 18-month period concluding in March 1982. Seventy-two (31.7%) of the children died; 28 children (38.9%) had cerebroventricular haemorrhage, 35 (48.6%) showed no bleeding and there were nine (12.5%) with no data. Paired necropsy and ultrasound data were congruent in 22 (88%) of 25 children. One hundred and forty-eight (95.5%) of 155 survivors were seen at 2 years of age. Forty-one (28%) had cerebroventricular haemorrhage; nine children (6%) had both ventricular dilatation and haemorrhage and two had ventricular dilatation alone. Apart from a marginal advance in gestation and higher number of immigrant and less educated mothers in children without cerebroventricular haemorrhage, all other perinatal, biographical and social variables between those with haemorrhage and those without were similar. The major handicap rate overall was 14.2% (21 patients). The children with cerebroventricular haemorrhage had a trend for greater prevalence of handicap and lower mean Bayley psychological scores. This was even more evident with ventricular dilatation being present. Of children with major handicap 57.1% (12/21) had normal serial ultrasound findings during their primary hospitalization. Major handicap occurred in 15% (3/20) of children with grade 1 haemorrhage, 23.5% (4/17) with grade 2 or 3 bleeds and 25% (1/4) of those with grade 4 haemorrhage. Laterality of cerebral palsy did not correlate with ultrasound findings. Ultrasound findings did not improve statistical prediction of deaths or major handicap.

Paediatric follow-up of pregnancies complicated by subnormal oestriol excretion

A cohort of 1238 consecutive women seen early in pregnancy for accurate assessment of gestation had urinary excretion of oestriol measured at 30, 35 and 40 weeks; 92 had a low urinary oestriol excretion confirmed in hospital on at least one occasion. The women in the low-oestriol group were matched for racial origin and maternal age with 90 women in the study population who had persistently normal urinary oestriol excretion values (control group) and their infants were compared. Three infants born in the low-oestriol group and two in the control group subsequently died; 85 of the 89 (95.5%) survivors in the low-oestriol group and 84 of 88 (95.5%) control children were assessed by a paediatrician and a psychologist at the age of 6 years. Anthropometric measurements of children in the low-oestriol group at 6 years of age did not differ significantly from controls and their performance on most psychological tests was not significantly different. The subgroup of 25 children born to women with persistently low oestriol excretion during pregnancy showed a significant reduction in weight and head circumference at 6 years compared with the values in the control group and in the other children in the low-oestriol group. The children born to women with low oestriol excretion during pregnancy showed no increased evidence of developmental, neurological or physical defects at 6 years of age.

Survival rates of infants with birth weights between 501 and 1,000 g. Improvement by excluding certain categories of cases

Reported survival rates of infants with birth weights under 1,001 g vary greatly; by implication, high survival rates may be used as a measure of the standard of perinatal care. To illustrate the importance of precisely defining the population sample, we determined the survival rate to 2 years of 238 infants with birth weights of 501 to 1,000 g, born between 1977 and 1980. The rate was 33.6%; however, by excluding certain categories of patients, the survival rate was augmented to 46.9%. There were 36 infants who died in the delivery room and an additional 34 who died before the age of 3 hours in the intensive care unit; together they contributed 29.4% to the total mortality of 66.4%. This group is especially liable to influence reported survival rates. Although exclusion of patients is legitimate, the criteria need to be precisely defined if data between centers are to be compared.