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

Changing consumption of resources for respiratory support and short-term outcomes in four consecutive geographical cohorts of infants born extremely preterm over 25 years since the early 1990s

OBJECTIVES

It is unclear how newer methods of respiratory support for infants born extremely preterm (EP; 22-27 weeks gestation) have affected in-hospital sequelae. We aimed to determine changes in respiratory support, survival and morbidity in EP infants since the early 1990s.

DESIGN

Prospective longitudinal cohort study.

SETTING

The State of Victoria, Australia.

PARTICIPANTS

All EP births offered intensive care in four discrete eras (1991-1992 (24 months): n=332, 1997 (12 months): n=190, 2005 (12 months): n=229, and April 2016-March 2017 (12 months): n=250).

OUTCOME MEASURES

Consumption of respiratory support, survival and morbidity to discharge home. Cost-effectiveness ratios describing the average additional days of respiratory support associated per additional survivor were calculated.

RESULTS

Median duration of any respiratory support increased from 22 days (1991-1992) to 66 days (2016-2017). The increase occurred in non-invasive respiratory support (2 days (1991-1992) to 51 days (2016-2017)), with high-flow nasal cannulae, unavailable in earlier cohorts, comprising almost one-half of the duration in 2016-2017. Survival to discharge home increased (68% (1991-1992) to 87% (2016-2017)). Cystic periventricular leukomalacia decreased (6.3% (1991-1992) to 1.2% (2016-2017)), whereas retinopathy of prematurity requiring treatment increased (4.0% (1991-1992) to 10.0% (2016-2017)). The average additional costs associated with one additional infant surviving in 2016-2017 were 200 (95% CI 150 to 297) days, 326 (183 to 1127) days and 130 (70 to 267) days compared with 1991-1992, 1997 and 2005, respectively.

CONCLUSIONS

Consumption of resources for respiratory support has escalated with improved survival over time. Cystic periventricular leukomalacia reduced in incidence but retinopathy of prematurity requiring treatment increased. How these changes translate into long-term respiratory or neurological function remains to be determined.

Factors associated with fall in neonatal intubation rates in the United Kingdom - prospective study

OBJECTIVE

To investigate the trend of neonatal resuscitation by intubation or mask ventilation over time and to assess its association with changes in prevalence of caesarean section and use of general anaesthesia in labour.

METHODS

All women booking pregnancy at any of 15 maternity units, analysed using logistic regression.

DESIGN

Prospective study.

SETTING

UK hospital-based maternity units (15 centres).

POPULATION

A total of 221,322 first singleton births of babies weighing 200 g or more in the St Mary's Maternity Information System cohort, 1988-2000, covering the North West Thames area of London.

MAIN OUTCOME MEASURES

Prevalence of intermittent positive-pressure ventilation (IPPV) (by intubation or mask) by calendar year.

RESULTS

Overall use of IPPV decreased markedly (two-sided P<0.01) over the course of the study, and this decrease was evident by all modes of delivery. Adjusted mean prevalence of intubated IPPV decreased from 0.51% (95% CI 0.44-0.58) in 1988 to 0.07% (95% CI 0.06-0.09) in 2000. There was a similar decrease in the prevalence of IPPV by mask. However, despite substantial increases in prevalence of caesarean sections and reductions in the use of general anaesthesia over the course of the study, adjusting for these variables made little difference to the temporal trends in intubation or use of mask ventilation.

CONCLUSIONS

There has been a marked reduction in the prevalence of infants given resuscitation by positive-pressure ventilation that cannot be explained by changes in the prevalence of caesarean section or use of general anaesthesia in labour.

The relationship between delivery mode and mortality in very low birthweight singleton vertex-presenting infants

OBJECTIVE

To investigate the factors associated with caesarean delivery and the relationship between mode of delivery and mortality in singleton vertex-presenting very low birthweight (< or = 1500 g) live born infants.

DESIGN

Observational population-based study.

SETTING

Data collected from all 28 neonatal departments comprise the Israel National Very Low Birth Weight Infant Database.

POPULATION

2955 singleton vertex-presenting very low birthweight infants registered in the database from 1995 to 2000, and born at 24-34 weeks of gestation.

METHODS

The demographic, obstetric and perinatal factors associated with caesarean delivery and subsequent mortality were studied. The independent effect of the mode of delivery on mortality was tested by multiple logistic regression.

MAIN OUTCOME MEASURE

Mortality was defined as death prior to discharge.

RESULTS

Caesarean delivery rate was 51.7%. Caesarean delivery was directly associated with increasing maternal age and gestational age, small for gestational age infants, maternal hypertensive disorders and antepartum haemorrhage, and was inversely related to premature labour and prolonged rupture of membranes. Factors associated with increased survival were increasing gestational age, antenatal corticosteroid therapy, maternal hypertensive disorders and no amnionitis. Mortality rate prior to discharge was lower after caesarean delivery (13.2% vs 21.8%), but in the multivariate analysis, adjusting for the other risk factors associated with mortality, delivery mode had no effect on infant survival (OR 1.00, 95% CI 0.74-1.33). In a subgroup with amnionitis, a protective effect of caesarean delivery was found.

CONCLUSIONS

Caesarean delivery did not enhance survival of vertex-presenting singleton very low birthweight babies. Caesarean delivery cannot be routinely recommended, unless there are other obstetric indications.

Regionalized long-term follow-up

The importance of population-based long-term follow-up studies of geographically determined cohorts to evaluate the effectiveness, efficiency and availability of a regionalized perinatal-neonatal care programme is demonstrated by the Victorian Infant Collaborative Study Group. The survival and quality of survival of consecutively born extremely-low-birthweight infants below 1000 g or extremely preterm infants below 28 weeks' gestation in the state of Victoria were assessed up to 14 years of age over four distinctive eras: 1979-1989, 1985-1987, 1991-1992 and 1997. Both survival and quality-adjusted survival rates rose progressively in all birth weight and gestation subgroups, associated with progressively more such infants being born in level III perinatal centres. Cost-effectiveness and cost-utility ratios remained stable overall, with efficiency gains in the smaller infants over time. Regionalized long-term follow-up provides unique information that is not available from institution-based studies, which is vital to the regional organization of perinatal-neonatal care.

The relationship between Caesarean section and neonatal mortality in very-low-birthweight infants born in Washington State, USA

We examined the associations between Caesarean section and neonatal mortality in singleton liveborn very-low-birthweight (VLBW) infants (500-1499 g) born during 1984-95 in Washington State, USA, using data from the Washington State birth certificate files. The infants included in this study had no life-threatening congenital malformations and had not been delivered by a repeat Caesarean without a trial of labour (n = 5182). For infants weighing 500-749, 750-999, 1000-1249 and 1250-1499 g, the neonatal mortality rates were 57.8%, 18.6%, 9.7% and 4.7%, respectively, and the Caesarean section rates were 28.4%, 47.8%, 48.0% and 44.6%. The adjusted odds ratios (ORs) for neonatal death associated with Caesarean section were 0.55 [95% confidence interval 0.38, 0.78] for the 500-749 g infants (n = 1059), and 1.15 [0.91, 1.45] for the larger (750-1499 g) infants, after adjustment for birth year, type of hospital, birthweight, presence or absence of labour, breech/malpresentation, and other obstetric indications for Caesarean section (prolapsed cord, placenta praevia, eclampsia, pre-eclampsia and chronic hypertension). However, when the larger (750-1499 g) vertex-presenting (n = 3248) and breech/malpresenting (n = 809) infants were considered separately, the adjusted ORs were 1.42 [1.05, 1.91] and 0.37 [0.23, 0.58] respectively. In contrast, among infants weighing 500-749 g, the ORs were not modified by presentation. The results were similar when we restricted analyses to infants without the above obstetric indications for Caesarean section. Because such an observational study is liable to unmeasurable biases and incomplete reporting of obstetric complications, these OR estimates may be subject to residual confounding. In their present state, these recent population-based data support the view that Caesarean sections do not enhance the neonatal survival of larger (> 750 g) VLBW babies when obstetric complications are absent. The possibility of a protective effect of Caesarean section on the survival of breech/malpresenting infants and infants weighing 500-749 g deserves further studies.

Trends in stillbirths and neonatal deaths for very pre-term infants (< 32 weeks' gestation) born in Victoria, 1986-1993

We have examined the trends in stillbirth rates and neonatal mortality rates of infants of 20-31 weeks' gestational born in Victoria during 1986-1993 (n = 6,462), using data from the Victorian Perinatal Data Collection Unit. Seventy four percent of all infants and 83% of all liveborn infants were born in level 3 hospitals. Both stillbirth and neonatal mortality rates were lower for infants of higher gestational ages, and those born in level 3 hospitals. During 1986-1993, annual stillbirth rates remained steady, with mean values of 61.2%, 40.2%, 24.7%, 16.0%, and 11% for infants of gestational ages 20-23, 24-25, 26-27, 28-29, and 30-31 weeks, respectively. The neonatal mortality rates decreased from 76.1 to 38.6%, 42.3 to 17.6%, 12.9 to 6.0%, and 8.4 to 3.7% for liveborn infants of gestational ages 24-25, 26-27, 28-29, and 30-31 weeks, respectively. The time-related falls in neonatal mortality were not due to changes in Caesarean section rates, intubation rates, or the proportions of infants born in, or transferred to, level 3 hospitals. They probably reflect continuing improvements in perinatal care.

Triplets and quadruplets born in Victoria between 1982 and 1990. The impact of IVF and GIFT on rising birthrates

OBJECTIVES

To examine the perinatal characteristics of all higher order multiple births (133 sets of triplets and six sets of quadruplets) in the State of Victoria between 1982 and 1990. To compare the rising higher order multiple birth rates in Victoria with those in the other States of Australia, and to assess the impact of in-vitro fertilisation (IVF) and gamete intrafallopian transfer (GIFT) on these rising birth rates.

DESIGN

Retrospective review of all higher order multiple births registered in Victoria and other States of Australia between 1982 and 1990, and in particular those resulting from IVF and GIFT.

DATA SOURCES

Victorian Perinatal Data Collection Unit, Australian Bureau of Statistics, National Perinatal Statistics Unit, data from Victorian IVF and GIFT units.

MAIN OUTCOME MEASURES

Higher order multiple birth rates and perinatal mortality rates.

RESULTS

The higher order multiple birth rates in Victoria rose from 3.5 per 10,000 in 1982 to 10.9 per 10,000 in 1990. The average perinatal mortality rates for the Victorian triplets and quadruplets born during this period were 10.8% and 25.0%, respectively. The rates of caesarean section were 70% and 83%; the proportions of deliveries in level III hospitals, 75% and 100%; and the mean maternal lengths of stay in hospital, 32 and 57 days, respectively. Endotracheal intubation was performed at birth in 18.5% of all infants. The proportions of triplet and quadruplet pregnancies in Victoria owing to IVF and GIFT rose during this period, reaching a peak of 42% in 1990. In the other States, the birth rates for higher order multiples increased at 1.8 times the rate observed for Victoria, with IVF and GIFT contributing to an estimated 43% of these conceptions between 1985 and 1989.

CONCLUSION

Restrictions on the numbers of embryos/oocytes transferred during IVF and GIFT should reduce the frequency of higher order multiple births.

Preventing and managing prematurity

In the past decade the prevention and management of prematurity have begun to be addressed with more appropriate designs. A few strategies--very few--can now be recommended. A few, some widely implemented, can be abandoned. The risks and benefits of most interventions still require clarification.