Survival and 2-year outcome of extremely preterm infants

Outcome of very-low-birth-weight (< 1,500 grams) infants born to mothers with diabetes

Premature delivery is common in pregnancies complicated by maternal diabetes. However, the outcome of very-low-birth-weight infants (VLBWI) born to mothers with diabetes is not known. Employing a matched double-cohort design, we investigated the influence of maternal diabetes on the outcome of VLBWI born in Winnipeg from 1988 to 1994. We compared mortality rates and early and late morbidity rates in VLBWI born to mothers with diabetes mellitus (DM) (cases, n = 43, 23 with gestational DM and 20 with pregestational DM) and without DM (controls, n = 539). Controls were matched for gestational age (GA), sex, and the year of birth. All subjects were enrolled in the Newborn Follow-Up Program. Relative risks and 95% confidence limits were calculated for each variable and Chi 2 analysis, Student t-test, and Mann-Whitney test were used as appropriate for analysis. Diabetes mellitus control was assessed by conventional criteria. There were no differences between cases and controls in mode of delivery, birth weight (mean +/- SD, 1,160 +/- 25 g vs 1,110 +/- 26 g), GA (29 +/- 2.8 wk vs 29 +/- 2.4 wk), smallness for gestational age (35% vs 30%), head circumference (26.5 +/- 1.9 vs 26.2 +/- 2.2 cm), length (38.8 +/- 2.8 vs 37.5 +/- 3.7 cm), Apgar score < 4 at 1 min (42% vs 40%) and < 7 at 5 min (37% vs 42%). Incidence of hyaline membrane disease (60% vs 71%), bronchopulmonary dysplasia (33% vs 31%), patent ductus arteriosus (30% vs 43%), necrotizing enterocolitis (12% vs 12%), sepsis (23% vs 25%), acute renal failure (9% vs 10%), intraventricular hemorrhage--all grades (74% vs 64%), retinopathy of prematurity--all stages (30% vs 26%), median days on ventilator (4 vs 4 days), and median days on supplemental oxygen (46 vs 42 days) were similar in both groups (p = NS, 95% confidence limits included 1 for all of these variables). There was no significant difference in mortality (21% vs 15%) or the incidence of major congenital anomalies. Weight, head circumference, and length at 6, 12, and 18 months were similar in both groups. There were no group differences in developmental quotients, prevalence of neurodevelopmental impairments, respiratory morbidity, or number of hospitalizations up to the last follow-up (18 months). Our data suggest that with contemporary perinatal care there is no significant increase in mortality rates or early and late morbidity rates between VLBWI born to mothers with DM and VLBWI of nondiabetic mothers. It seems that with reasonable diabetic control, prematurity rather than the diabetic state determines the neonatal outcome, and this knowledge can be useful in parental counselling.

Acute renal failure in the newborn: incidence and outcome

OBJECTIVE

To describe an experience from a developing country of newborn renal disease particularly those without advanced neonatal care.

METHODOLOGY

Prospective evaluation from a referral hospital, North-East of Nigeria between 1 July 1990 and 30 June 1994. Babies admitted for any morbidities who were diagnosed as being in acute renal failure (ARF) during the study period (non-oliguric inclusive). Onset of ARF; day on which oliguria or anuria detected, or serum urea first exceeded 10 mmol/L. Urine output quantitated from carefully bagged urine and suprapubic bladder aspiration, and venous blood regularly obtained for serum electrolytes, urea and creatinine. Fractional excretion of sodium (FE(Na)) and renal failure index (RFI) were determined on some babies.

RESULTS

Forty-three neonates (M:F; 3.3:1) with ARF, the majority (27) of whom were out-born, and 14, 26 and three were preterm, full-term and post term, respectively. Encountered incidence was 3.9/1000 live births with a high prevalence rate; 34.5/1000 admissions. A significantly greater incidence was seen in the latter half of study; 10.7 vs 53.7/1000, P < 0.05. Early ARF occurrence (aged; 0-5 days) in 33 (77%) of babies. The aetiology was comprised of perinatal asphyxia, sepsis, obstructive uropathy and miscellaneous in 53.4%, 32.6%, 9.3% and 4.7%, respectively. Twenty-two (51.2%) deaths occurred; however, the exact causes were indeterminable. Fractional excretion of sodium (FE(Na)) and renal failure index (RFI) were of < 1.75% and < or = 2.0, respectively, significantly differentiated sepsis (intrinsic) from perinatal asphyxial (pre-renal) ARF; P < 0.01. No case of persistent renal failure occurred.

CONCLUSION

Our FE(Na) value (although less than reported in previous literature from affluent societies) remained sensitive (along with RFI) in differentiating aetiological group of ARF. Our data and medical management outcome, despite absence of level-III care, support the need for good resuscitation, careful monitoring and constant re-evaluation. The effect of salbutamol on hyperkalaemia is emphasized.

Neonatal mortality rate: is further improvement possible?

OBJECTIVE

To determine whether improvement in neonatal and infant mortality rates is possible or likely.

SETTING

Regional neonatal intensive care unit.

METHODS

Experience during a decade (1982-1991) was evaluated. We determined postnatal age at death and birth weight-specific and gestational age-specific mortality rates. Neonatal deaths (deaths before discharge) were categorized as "possibly preventable" or "probably unpreventable."

RESULTS

Deaths occurring after 28 days ("postponed" deaths) contributed 9% of the total for the decade, and 5% for those with extremely low birth weight (ELBW; < 1000 gm) during the last 6 years; 47% of all deaths and 65% of deaths of ELBW infants occurred within 24 hours of birth. Congenital malformations accounted for 7%, 54%, and 66% of deaths when birth weight was 500 to 1499 gm, 1500 to 2499 gm, and > or = 2500 gm, respectively. In infants with birth weight > or = 1000 gm, probably unpreventable deaths (predominantly from congenital malformations, but also including hydrops and inborn errors of metabolism) accounted for 61% of deaths. Of deaths of ELBW infants, extreme prematurity (500 to 750 gm) accounted for 58%; major malformations and pulmonary hypoplasia contributed an additional 9%.

CONCLUSION

During the decade, the gestational age at which there was a 50% survival rate fell from 26 weeks to 24 weeks and a marked increase in the survival rate occurred at birth weights < 1500 gm (VLBW) after the introduction of exogenous surfactant therapy. The number of possibly preventable deaths is now very small. For any substantial impact on mortality rates, it will be necessary to lower VLBW and ELBW rates.

The role of life events in different categories of preterm birth in a group of women with previous poor pregnancy outcome

The aim of the present study was to determine whether mothers reporting more life events experience more preterm births following both complicated and uncomplicated pregnancies. A Life Events Inventory was administered prospectively to women at high risk for poor obstetric and neonatal outcomes who took part in the Pregnancy Home Visiting Program (PHVP), a randomized controlled trial of the effect of a programme of antenatal home visits by midwives on the incidence of preterm birth. This study took place in Western Australia in the years 1984-1987. All women in the study had had a previous poor pregnancy outcome. The women were classified into two groups--those with complicated and those with uncomplicated pregnancies. Pregnancies classified as 'complicated' were defined as a pregnancy in which there was antenatal hospital admission(s) for hypertension, antepartum haemorrhage or other medical reason except for preterm birth. Pregnancies classified as 'uncomplicated' refer to all pregnancies without these complications. No significant association was found between life events and preterm birth although the total stress score for women with uncomplicated pregnancies almost reached significance, as did the number of life events for both women with complicated and women with uncomplicated pregnancies considered together. Life events were not shown to have a predictive relationship to preterm birth even when stratified by etiologically different groups. However, although stress was not an important predictor of preterm birth in this group of women at biological risk it may yet be so in a group at social risk.

Extremely low-birth-weight infants less than 901 g. Growth and development after one year of life

In a long-term prospective control study, 20 extremely low-birth-weight infants with birth weights between 500 and 900 g (mean 755 +/- 109 g) and gestational ages between 24 and 30 weeks (mean 26.2 +/- 1.8 weeks) were compared with 20 full-term infants, after the first year of life for growth, development and continuing morbidity after discharge from the intensive care unit. The total rate of neurological abnormalities was 17%; the rate of infantile post-hemorrhagic hydrocephalus requiring shunt operations was 8.7%, while 13% had retinopathy of prematurity with vision deficit, but none was blind. The hospital readmission rate was 70%, but for most infants only one or a few readmissions were needed whereas three infants with chronic lung disorders required frequent hospital readmissions, mainly for respiratory infections. Apart from 4 infants with major cerebral neonatal complications, 16 of 20 extremely low-birth-weight infants (80%) showed development within the normal range at one year of age, although with delay in some areas in comparison with full-term control infants. Follow-up into preschool and school age is in progress. We cautiously suggest that the results at the one year follow-up do indicate a possible favourable long-term outcome for many of these extremely low-birth-weight infants with normal cognitive development and with no major neurological sequelae.

Extremely low birth weight infants less than 901 g. Impact on the family during the first year

In a longterm prospective study 20 extremely low birth weight (ELBW) infants with birth weight between 500 and 900 g (mean 755 +/- 109 g) and gestational age between 24 and 30 weeks (mean 26.2 +/- 1.8 w) were compared with 20 fullterm infants. This part of the study focuses on the impact on the family. Structured parental interviews were conducted in the postnatal period and at the end of the first year concerning the pregnancy, the delivery and the infant's health and behaviour during the first year of life. Questions about the parents' and siblings' reactions, physical symptoms and the strains on the husband-wife relationship were also asked. It was found that the mothers of the ELBW infants had more fertility problems, more physical symptoms during the pregnancy and the infant's first year of life. The birth of an ELBW infant caused crisis reactions in 85% of the mothers and 65% of the fathers. Fifty-eight per cent of the ELBW parents and 21% of the parents in the control group reported that the stress during the infant's first year had led to strains on the husband-wife relationship. It is evident that the birth of an ELBW infant had an impact on the whole family. However, we found no relationship between permanent neurological injuries in the infant and strong reactions in the family members. On the other hand, the parental relationship in the perinatal period seems to be of significance, as does the length of time the infant was hospitalized during its first year of life.

Delivery of very premature infants: does the caesarean section rate relate to mortality, morbidity, or long-term outcome?

A retrospective analysis of obstetric factors influencing mortality and morbidity of very premature infants (1500 g, less than or equal to 32 weeks' gestation) was undertaken. The study included 275 such infants born in the Department of Obstetrics of the University of Tübingen during the period January 1977 to June 1987. The caesarean section rate of very preterm infants increased from 28% during the period 1977-1982 to 87% during the period 1982-1987 (P less than 0.005), accompanied by an increase in survival rate from 63% to 70%. The improvement in survival rate was statistically significant for the group with birth weight 751-1000 g (P less than 0.01). The overall mortality rate was 31% after caesarean section and 36% after vaginal delivery. Amongst the causes of death of the non-survivors, acidosis was more frequent and amniotic infection syndrome less frequent in the infants delivered vaginally than in those delivered abdominally. The proportion of children with normal development at two years of age was significantly (P less than 0.02) greater amongst those born in 1982-1987 than in those born in 1977-1981. The interpretation of these findings is by no means clear but must include the hypothesis that the increased caesarean section rate may be incidental and in no way related to the improved outcome.

The short-term outcome of singleton infants delivered before 28 weeks' gestation

The short-term outcome of 271 singleton infants born at Westmead Hospital between 20 and 28 weeks' gestation, during a 5-year period are reported. The earliest gestation at which there was a survivor was 23 weeks. Survival rates from 23-23+6 weeks to 27-27+6 weeks, excluding congenital abnormalities, were 8.3% to 77.5% respectively. Overall 21.9% of deaths occurred in the delivery suite, 63.4% in the neonatal period, 3.7% in the postneonatal period in hospital and a further 11% after discharge from hospital. Of survivors at 12 months, 18.8% were judged to have a major impairment.

Outcomes of extremely-low-birth-weight infants between 1982 and 1988

Infants with birth weights under 750 g are disproportionately represented in perinatal mortality and morbidity rates. We reviewed the outcomes of 98 infants delivered at our perinatal center between July 1982 and June 1985 (period 1) whose lengths of gestation were 20 or more weeks and whose birth weights were under 750 g, and compared them with the outcomes of 129 such infants born between July 1985 and June 1988 (period 2). The frequency of cesarean section increased from 12 to 19 percent between the two periods. During the entire six-year period, 12 percent of the infants with birth weights under 500 g were intubated, as compared with 28 percent of those between 500 and 599 g, 60 percent of those between 600 and 699 g, and 90 percent of those between 700 and 749 g. The frequency of endotracheal intubation increased between the two periods only for infants with birth weights above 500 g (P less than 0.02). Despite more aggressive treatment, survival did not change, although the mean time to death among infants transferred to the neonatal intensive care unit increased from 73 to 880 hours. Among all live-born infants with birth weights under 750 g, the rate of survival was 20 percent during period 1 and 18 percent during period 2, but 48 and 43 percent of those transferred to the neonatal intensive care unit survived in the two periods reviewed. Neonatal morbidity also did not change. Among survivors at a corrected age of 20 months, 4 of 18 born during period 1 and 7 of 14 born during period 2 had moderate-to-severe neurodevelopmental impairment. When all live-born infants of less than 28 weeks' gestation were considered, only 8 percent of those born at 23 weeks survived, as compared with 16 percent of those born at 24 weeks, and 53, 63, and 72 percent of those born at 25, 26, 27 weeks, respectively. Thus, despite a tendency to perform more cesarean sections and active resuscitations, no improvement in the survival of babies with lengths of gestation below 25 weeks or birth weights under 750 g was observed. The probability of survival is very poor if the length of gestation is less than 24 weeks or the birth weight less than 600 g.

Neonatal outcome of extremely small low birthweight liveborn infants below 901 g in a Swedish population

In a regional population of 32,120 liveborn newborn infants 65 (0.2%) had a birthweight less than or equal to 900 g (extremely small low birthweight = ESLBW) with mean gestational age 26.4 (range 22-31) completed weeks of gestation. The total 0-1 year survival rate was 48%. For the 42 infants treated in the Level III regional neonatal intensive care unit (NICU) the 0-1 year survival rate was 55% versus 34% for 23 infants not transferred to the Level III unit. In the ESLBW infants treated in the regional NICU the major complications were respiratory disorders requiring artificial ventilation (73%), bronchopulmonary dysplasia (26%), intracranial haemorrhages (40%), symptomatic persistent ductus arteriosus (36%) and sepsis (14%), persistent retinopathy of prematurity (8%). Duration of NICU treatment was 51 days (range 10-95) for survivors. Mode of delivery and rate of perinatal complications did not differ between survivors and non-survivors. Previous legal abortion occurred in 24%, fertility problems in 29% and 21% of the mothers were immigrants. Otherwise no significant abnormalities were found in maternal or socioeconomic conditions. Factors deciding neonatal outcome in the tiniest babies seem to be a combination of prenatal circumstances and neonatal minute fine care procedures.

Treatment of renal failure in neonates

Thirty neonates with acute renal failure were studied, 27 of whom died (90%) including nine of 12 treated by peritoneal dialysis. Three main aetiological groups were identified. Septicaemia was a principal cause of late onset acute renal failure, with an incidence equal to that of serious perinatal disorders. It is recommended that tolazoline should be used with caution in the treatment of hyperkalaemia as it may have a role in the aetiology of acute renal failure, the incidence of which is increasing.

A review of the obstetric and medical complications leading to the delivery of infants of very low birthweight

The delivery of very-low-birthweight infants is one of the major problems in human reproduction today. This study describes the principal obstetric and medical complications which led to the birth of 417 infants of 500-g to 1499-g birthweight, at the tertiary-level perinatal centre in Western Australia during the two years 1980 and 1985. An altered pattern of obstetric management of these cases was observed in 1985 compared to the management in 1980. In 1985, fewer deliveries were a result of spontaneous labour; tocolytic agents had been used in a smaller proportion of pregnancies; more infants were delivered by caesarean section without a preceding labour; and the still-birth rate was lower. Uncomplicated preterm labour was not the major cause of birth of very-low-birthweight infants. The most common factors that precipitated the delivery of very-low-birthweight infants were preterm premature rupture of the membranes (30% of cases), severe hypertension (19% of cases), antepartum haemorrhage (17% of cases) and preterm labour (17% of cases). Very low birthweight has a multifactorial aetiology, and its prevention will require a multidisciplinary approach.

Maternal and perinatal outcome of expectant management of premature rupture of membranes in the midtrimester

The purpose of this clinical investigation was to determine the maternal and perinatal results of continuing pregnancy in 118 consecutive patients with premature rupture of the membranes at 16 to 26 weeks. The mean gestational age at diagnosis of premature rupture of the membranes was 23.1 +/- 2.7 weeks, with a median of 23.5. The interval from rupture to delivery ranged from 1 to 152 days, with a mean of 13. There was no correlation between gestational age at the time of rupture and the latency period. Thirty-five patients received tocolytic agents and 24 received steroids. Forty-eight percent were delivered within 3 days, 67% within 1 week, and 83% within 2 weeks. There was one maternal death from sepsis; 46 (39%) had amnionitis, and 8 (6.8%) had abruptio placentae. The mean gestational age at the time of delivery was 24.7 +/- 3.6 weeks. The 118 pregnancies resulted in 124 births. There were 17 stillbirths and 67 neonatal deaths, for a total perinatal mortality of 67.7%. In patients with premature rupture of the membranes at less than or equal to 23 weeks the perinatal survival rate was 13.3%, while it was 50% in patients with premature rupture of the membranes at 24 to 26 weeks (p less than 0.0001). Information was charted at 3 to 36 months for 34 of 40 surviving infants. The intact survival rate in this group was 67%, and 33% had some form of developmental abnormality. Expectant management in such cases can be justified in only a limited number of patients (patients who understand and accept the risks and patients beyond 23 weeks of gestation).

Preterm birth at 23 to 26 weeks' gestation: is active obstetric management justified?

To determine if active perinatal management was justified in preterm deliveries at less than or equal to 26 weeks' gestation, the outcome (survival and short- and long-term morbidity) of 43 infants (group I) born between 23 and 26 weeks' gestation was compared with that of 17 infants (group II) born at 27 weeks' gestation. Of the 12 surviving infants in group I (survival 28%), 11 were ventilated (median = 50 days), eight had moderate to severe bronchopulmonary dysplasia, and four had mild retrolental fibroplasia. At follow-up, two infants had physical disabilities with moderate to severe functional impairment, one had a minor disability, and nine had normal neurodevelopment. In contrast, of the 13 surviving infants in group II (survival 76%), nine were ventilated (median = 8 days), six had moderate to severe bronchopulmonary dysplasia, and six had mild RLF. At follow-up, one infant had a physical disability with moderate to severe functional impairment, four had minor disabilities, and eight had normal development. Perinatal factors that positively influenced survival in the two groups combined included active perinatal management, antenatal steroids, female sex, and absence of clinical chorioamnionitis and asphyxia. Although group I infants had a significantly higher mortality rate (p less than 0.05) and required a longer duration of ventilation (p less than 0.05), no differences in the incidence of postnatal complications or long-term morbidity at 2 to 4 years of age were evident between the two groups.

Outcome of singleton infants delivered vaginally or by caesarean section at 23 to 28 weeks' gestation

The survival and impairment rates of 276 inborn singleton infants of 23-28 weeks' gestation were reported according to route of delivery and mode of presentation. The Caesarean section rate was 29% overall, ranging from 13% at 25 weeks to 46% at 28 weeks. In the vertex group, no significant difference in survival or impairment rate was found between Caesarean and vaginal births. In the non-vertex group, Caesarean births had a similar survival rate but a significantly lower impairment rate compared to vaginal births. For Caesarean births, no significant difference in survival or impairment rate was found between vertex and non-vertex groups. In contrast, for vaginal births, the mode of presentation was important: the non-vertex group had a significantly lower survival rate and higher impairment rate compared to the vertex group. We found no evidence to support the use of Caesarean section in extremely preterm infants with vertex presentation, except for recognized maternal or fetal indications. The findings in the non-vertex group indicated that there is a definite need for a randomized clinical trial to investigate the possible benefits of Caesarean section in extremely preterm infants with non-vertex presentation.

Mortality and morbidity in infants born between 20 and 28 weeks gestation

Of 149 infants with ultrasound evidence of gestational age, born in Ninewells Hospital at between 20 and 28 weeks gestation over a 5-year period, 50 were alive at birth. Of these infants, 21 died within 1 week, a further three died within 1 month and a further two within 18 months. Of the 24 survivors, 8 (33%) have significant handicap. The obstetric factors leading to delivery and the mode of delivery are discussed.

Periventricular haemorrhage and leukomalacia in extremely low birthweight infants

Forty (49%) of 82 extremely low birthweight (ELBW, less than 1000 g) infants had periventricular haemorrhage (PVH). Ten (12%) had germinal layer haemorrhage (GLH) alone, 16 (20%) had intraventricular haemorrhage (IVH) and 14 (17%) had intracerebral haemorrhage (ICH). Almost all the cases of PVH had developed by 4 days of age. Small-for-gestational age infants (12% of study population) had a significantly lower incidence and severity of PVH than appropriate-for-gestational age infants. Of 94 infants born between 23 and 28 weeks gestation, 45 (48%) had PVH. The PVH incidence was 60% in those of 23-26 weeks and 38% in those of 27-28 weeks. The hospital survival rate of ELBW infants was 69% in those without PVH and 43% in those with PVH; 70% in GLH alone; 50% in IVH and 14% in ICH. Three survivors developed post-haemorrhage hydrocephalus of whom two required ventriculoperitoneal shunting. Five survivors developed periventricular leukomalacia (PVL) evidenced by cysts identified between 3 and 7 weeks of age. A significant decrease in the incidence of PVH occurred over the study period (67% in 1982, 38% in 1983 and 33% in 1984). This decrease was seen for all grades of PVH. The reasons for this decreased incidence are still to be ascertained but this trend suggests that improvements in neonatal intensive care have the potential to improve the neurological outcome of more recent ELBW survivors.

Postnatal growth in infants born before 30 weeks' gestation

The postnatal weight pattern up to 14 weeks after birth was determined in 184 singleton survivors born at 23 to 29 weeks' gestation in whom routine parenteral nutrition was used before milk feeding was established. A mean postnatal weight loss of 14% of birth weight occurred at a mean of 6 days. The more immature infants had significantly higher postnatal weight loss and longer time to regain birth weight despite a higher volume intake in the first week. From the fourth postnatal week all gestational subgroups had a mean weight gain at above intrauterine growth rate. As a result of the initial period of weight loss, however, the mean body weight remained below the 10th percentile of the intrauterine growth curve. The early growth rate in infants small for gestational age was higher than those who were appropriate weight for gestation, although the mean body weight of the former group remained significantly lower at 2 years.

Outcome of extremely-low-birthweight infants

The overall 1-year survival rate of 261 infants born at 500 g-999g over a 7-year period was 46%. The survival rate of the 220 inborn infants, corrected for birth defects, would have increased from 47% to 57% if delivery room deaths were excluded and to 62% if postneonatal deaths had also been ignored. Survival improved progressively with increasing 100g weight groups. The disability rate in the 108 survivors who were at least 2 years old corrected for prematurity was 28% with little variation between the 100g weight groups. There were no significant trends in annual perinatal mortality, 1-year survival and disability rate in survivors over the study period for the inborn population. The male infants had significantly lower normal-survival rate than the female infants. Small-for-gestational-age infants, comprising 11% of the inborn group, had significantly better survival but a higher disability rate. Multiple births had significantly lower survival and normal-survival rates than had singleton births. Infants whose mothers were transferred for delivery at the perinatal centre before onset of labour had a significantly better survival rate than those whose mothers had 'booked' and those who were transferred in labour.

Effect of neonatal periventricular haemorrhage on neurodevelopmental outcome

All 56 infants born between 23 and 28 weeks' gestation admitted to this hospital in 1981 were examined for periventricular haemorrhage with cerebral ultrasonography. Haemorrhage was diagnosed in 34 (61%)-12 (22%) had germinal layer haemorrhage, 18 (32%) had intraventricular haemorrhage, and four (7%) had intracerebral haemorrhage. The two year outcome of survivors with and without periventricular haemorrhage was compared to determine the effect on neurodevelopment. Only three (16%) of 19 infants with normal scans or germinal layer haemorrhages had evidence of major disability but nine (75%) of 12 infants with intraventricular or intracerebral haemorrhage had major disability. The mental and psychomotor performance on the Bayley scales of infant development was also significantly worse in the latter group. All three survivors with intracerebral haemorrhage had major disability. The continuation of life support treatment for extremely preterm infants who are at very high risk of severe handicap is a matter of increasing concern in neonatal intensive care. Our results show that if extensive periventricular haemorrhage, in particular intracerebral haemorrhage, occurs in this gestational group, extreme pessimism is warranted.