Prenatal prediction of neonatal survival at the borderline viability

Prognostic Models Predicting Mortality in Preterm Infants: Systematic Review and Meta-analysis

CONTEXT

Prediction models can be a valuable tool in performing risk assessment of mortality in preterm infants.

OBJECTIVE

Summarizing prognostic models for predicting mortality in very preterm infants and assessing their quality.

DATA SOURCES

Medline was searched for all articles (up to June 2020).

STUDY SELECTION

All developed or externally validated prognostic models for mortality prediction in liveborn infants born <32 weeks' gestation and/or <1500 g birth weight were included.

DATA EXTRACTION

Data were extracted by 2 independent authors. Risk of bias (ROB) and applicability assessment was performed by 2 independent authors using Prediction model Risk of Bias Assessment Tool.

RESULTS

One hundred forty-two models from 35 studies reporting on model development and 112 models from 33 studies reporting on external validation were included. ROB assessment revealed high ROB in the majority of the models, most often because of inadequate (reporting of) analysis. Internal and external validation was lacking in 41% and 96% of these models. Meta-analyses revealed an average C-statistic of 0.88 (95% confidence interval [CI]: 0.83-0.91) for the Clinical Risk Index for Babies score, 0.87 (95% CI: 0.81-0.92) for the Clinical Risk Index for Babies II score, and 0.86 (95% CI: 0.78-0.92) for the Score for Neonatal Acute Physiology Perinatal Extension II score.

LIMITATIONS

Occasionally, an external validation study was included, but not the development study, because studies developed in the presurfactant era or general NICU population were excluded.

CONCLUSIONS

Instead of developing additional mortality prediction models for preterm infants, the emphasis should be shifted toward external validation and consecutive adaption of the existing prediction models.

No. 347-Obstetric Management at Borderline Viability

OBJECTIVE

The primary objective of this guideline was to develop consensus statements to guide clinical practice and recommendations for obstetric management of a pregnancy at borderline viability, currently defined as prior to 25+6 weeks.

INTENDED USERS

Clinicians involved in the obstetric management of women whose fetus is at the borderline of viability.

TARGET POPULATION

Women presenting for possible birth at borderline viability.

EVIDENCE

This document presents a summary of the literature and a general consensus on the management of pregnancies at borderline viability, including maternal transfer and consultation, administration of antenatal corticosteroids and magnesium sulfate, fetal heart rate monitoring, and considerations in mode of delivery. Medline, EMBASE, and Cochrane databases were searched using the following keywords: extreme prematurity, borderline viability, preterm, pregnancy, antenatal corticosteroids, mode of delivery. The results were then studied, and relevant articles were reviewed. The references of the reviewed studies were also searched, as were documents citing pertinent studies. The evidence was then presented at a consensus meeting, and statements were developed.

VALIDATION METHODS

The content and recommendations were developed by the consensus group from the fields of Maternal-Fetal Medicine, Neonatology, Perinatal Nursing, Patient Advocacy, and Ethics. The quality of evidence was rated using criteria described in the Grading of Recommendations Assessment, Development and Evaluation methodology framework (reference 1). The Board of the Society of Obstetricians and Gynaecologists of Canada approved the final draft for publication.

METHODS

The quality of evidence was rated using the criteria described in the Grading of Recommendations, Assessment, Development, and Evaluation methodology framework. The interpretation of strong and weak recommendations is described later. The Summary of Findings is available upon request.

BENEFITS, HARMS, AND COSTS

A multidisciplinary approach should be used in counselling women and families at borderline viability. The impact of obstetric interventions in the improvement of neonatal outcomes is suggested in the literature, and if active resuscitation is intended, then active obstetric interventions should be considered.

GUIDELINE UPDATE

Evidence will be reviewed 5 years after publication to decide whether all or part of the guideline should be updated. However, if important new evidence is published prior to the 5-year cycle, the review process may be accelerated for a more rapid update of some recommendations.

SPONSORS

This guideline was developed with resources funded by the Society of Obstetricians and Gynaecologists of Canada and the Women and Babies Program at Sunnybrook Health Sciences Centre.

RECOMMENDATIONS

Characterization of mothers at risk of delivery at the limit of viability and factors related to infant survival

OBJECTIVES

To determine the sociodemographic and clinical characteristics of mothers of infants at the limit of viability and to know the perinatal factors associated to infants' survival.

METHOD

Single-center cohort study of mothers and newborns assisted in our tertiary care center (2004-2010). Demographic and perinatal variables were compared between mothers who gave birth  ≤26 weeks GA and the general population. The association between perinatal factors and neonatal survival was studied by Cox regression analysis.

RESULTS

Mothers of newborns  ≤26 weeks (n = 136) had less education and pregnancy control. They had more frequently assisted reproductive technologies (ART) (5.2% versus 2.3%; p< 0.05), multiple gestations (16.6% versus 2.1%; p < 0.05), pregnancy complications and C-section (39.7% versus 13.4%; p  < 0.001). After correcting for confounders, the perinatal factors independently associated with a variation in the risk of mortality were the administration of antenatal steroid [aHR (95%CI): 0.465 (0.254-0.853), p = 0.013], singleton pregnancy [aHR (95%CI): 0.482 (0.279-0.834), p = 0.009], infant's temperature on admission [aHR (95%CI): 0.642 (0.426-0.968), p = 0.035] and CRIB score [aHR (95%CI): 1.151 (1.058-1.251), p  = 0.001].

CONCLUSIONS

Mothers of preterm infants at the limit of viability had more ART, multiple pregnancies, obstetrical complications and C-section. Infants' survival was independently associated to antenatal steroids, singleton pregnancy, temperature on admission and CRIB score.

Resuscitation of neonates at 23 weeks' gestational age: a cost-effectiveness analysis

OBJECTIVE

Resuscitation of infants at 23 weeks' gestation remains controversial; clinical practices vary. We sought to investigate the cost effectiveness of resuscitation of infants born 23 0/7-23 6/7 weeks' gestation.

DESIGN

Decision-analytic modeling comparing universal and selective resuscitation to non-resuscitation for 5176 live births at 23 weeks in a theoretic U.S. cohort. Estimates of death (77%) and disability (64-86%) were taken from the literature. Maternal and combined maternal-neonatal utilities were applied to discounted life expectancy to generate QALYs. Incremental cost-effectiveness ratios were calculated, discounting costs and QALYs. Main outcomes included number of survivors, their outcome status and incremental cost-effectiveness ratios for the three strategies. A cost-effectiveness threshold of $100 000/QALY was utilized.

RESULTS

Universal resuscitation would save 1059 infants: 138 severely disabled, 413 moderately impaired and 508 without significant sequelae. Selective resuscitation would save 717 infants: 93 severely disabled, 279 moderately impaired and 343 without significant sequelae. For mothers, non-resuscitation is less expensive ($19.9 million) and more effective (127 844 mQALYs) than universal resuscitation ($1.2 billion; 126 574 mQALYs) or selective resuscitation ($845 million; 125 966 mQALYs). For neonates, both universal and selective resuscitation were cost-effective, resulting in 22 256 and 15 134 nQALYS, respectively, versus 247 nQALYs for non-resuscitation. In sensitivity analyses, universal resuscitation was cost-effective from a maternal perspective only at utilities for neonatal death <0.42. When analyzed from a maternal-neonatal perspective, universal resuscitation was cost-effective when the probability of neonatal death was <0.95.

CONCLUSIONS

Over wide ranges of probabilities for survival and disability, universal and selective resuscitation strategies were not cost-effective from a maternal perspective. Both strategies were cost-effective from a maternal-neonatal perspective. This study offers a metric for counseling and decision-making for extreme prematurity. Our results could support a more permissive response to parental requests for aggressive intervention at 23 weeks' gestation.

Antenatal steroid exposure and outcomes of very premature infants: a regional cohort study

OBJECTIVE

To compare mortality, short-term morbidity and long-term neurodevelopmental outcomes of <29 week premature infants with antenatal steroid exposure (none, incomplete and complete).

PATIENTS AND METHODS

Multicentre retrospective cohort study, within a geographically defined area in Australia served by a network of 10 neonatal intensive care units (NICUs), of infants <29 weeks gestational age, admitted to NICUs between 1998 and 2004. Outcome measures included hospital survival, perinatal complications and functional disability at 2-3 years follow-up.

RESULTS

2549 neonates were included; 319 (12.5%) received no exposure to steroids. Hospital mortality (OR 0.59, 95% CI 0.45 to 0.76, p<0.001, intraventricular haemorrhage (IVH) (OR 0.58, 95% CI 0.42 to 0.81, p=0.001) and necrotising entercolitis (NEC) (OR 0.62, 95% CI 0.42 to 0.91, p=0.018) was less likely in infants with any steroid exposure. Any steroid exposure was associated with less need for surfactant (OR 0.41, 95% CI 0.30 to 0.57, p<0.001) and mechanical ventilation (OR 0.30, 95% CI 0.17 to 0.52, p<0.001). Subgroup analyses demonstrated differences in outcomes only with complete steroid coverage and not with incomplete coverage. Survival benefit and reduction in the incidence of severe IVH was evident from 24 to 28 weeks. Long-term neurodevelopmental data available for 1473 survivors showed no significant difference in outcomes with steroid exposure after multivariate analysis.

CONCLUSIONS

Exposure to a complete course of antenatal steroids is associated with higher infant survival rates, lower rates of severe IVH and NEC compared to an incomplete course or no exposure. Any exposure to steroids reduces the risk of moderate cerebral palsy, however, long-term neurodevelopmental outcome may not be affected by steroid exposure.

Periviable births: epidemiology and obstetrical antecedents

Confusion in terminology and non-standardized definitions can arguably be classified as the most important characteristics that lead to disparate study findings. While such situations abound in all of perinatal epidemiology, the study of "periviable birth" is a classic case in point. The most common term used to describe periviable birth has been extremely low birthweight (ELBW), often defined as newborns with birthweight below 1000g; yet, we identified 11 other descriptors for periviable birth. Due to the multitude of definitions, the reported incidence of periviable births varies from 0.03% to 1.9% (a relative difference of 7025%). Antecedent risk factors for periviable birth, though geographically heterogeneous, include nulliparity and multiple gestations, each accounting for one-third and one-fourth of all periviable births, respectively. Spontaneous preterm labor precedes 34% of these deliveries and premature rupture of membranes in 25%. The pregnancy was complicated by hypertensive disease in 21% and bleeding and chorioamnionitis in 18% each. Over 50% of these births are cesarean deliveries. Six clinical interventions before delivery that may improve outcomes include transfer of patient to a tertiary center, administration of antenatal corticosteroids, tocolytics, or antibiotics after premature rupture of membranes, assessment of fetal well-being with electronic fetal heart rate monitoring, and willingness to perform a cesarean delivery after the limit of viability is reached. While there is an accessible predictive model for mortality and long-term morbidities for newborns delivered at 22-25 weeks with weights of 400-1000g, it is hampered by the need to know the birthweight. In addition to reaching a consensus regarding what birthweight-gestational age thresholds determine a periviable birth, the acute need to optimize neonatal outcomes remains a paramount target worthy of future research, and efforts to advance obstetrical medicine are needed to minimize the likelihood of its occurrence.

The association between maternal country of birth and neonatal intensive care unit outcomes

BACKGROUND

Immigration is increasingly common worldwide and its impact on neonatal intensive care unit outcomes is uncertain.

AIMS

To determine the outcomes of children of immigrant mothers admitted to NICUs in New South Wales (NSW), Australia, between 2000 and 2006.

STUDY DESIGN

Record linkage study of routinely collected state-based health databases.

SUBJECTS

Infants of Australian-born (9813, 81.9%) and overseas born mothers (2166, 18.1%).

OUTCOME MEASURES

NICU and childhood outcomes to a maximum 5 years of age.

RESULTS

Immigrant mothers came from 122 countries, 897 (44%) from high income regions. Australian born mothers were more likely to be teenaged (Odds Ratio, 95% confidence interval: 3.07, 2.21-4.26), use drugs (3.55, 2.49-5.06) and suffer an antepartum hemorrhage (1.29, 1.14-1.48). They were less likely to have gestational diabetes (0.45, 0.38-0.54), fetal distress (0.75, 0.66-0.85) and intrauterine growth restriction (0.80, 0.67-0.93). Their infants were more likely to be admitted to the NICU for prematurity but less likely to have low 5 min Apgar scores (0.81, 0.69-0.93) or a congenital abnormality (0.79, 0.70-0.90). Infants of Middle-Eastern mothers had the lowest hospital survival rate (88.5%). Children of immigrant Asian mothers were least likely to be rehospitalized after NICU discharge (1.66, 1.27-2.17).

CONCLUSIONS

NICU outcomes are affected by maternal country of birth even within the same ethnic group. Further study regarding the impact of paternal race and immigration status and duration of residency will provide data for the changing cultural environment of global perinatal care.