Protocol for the development and validation of a risk prediction model for stillbirths from 35 weeks gestation in Australia.

BACKGROUND: Despite advances in the care of women and their babies in the past century, an estimated 1.7 million babies are born still each year throughout the world. A robust method to estimate a pregnant woman's individualized risk of late-pregnancy stillbirth is needed to inform decision-making around the timing of birth to reduce the risk of stillbirth from 35 weeks of gestation in Australia, a high-resource setting. METHODS: This is a protocol for a cross-sectional study of all late-pregnancy births in Australia (2005-2015) from 35 weeks of gestation including 5188 stillbirths among 3.1 million births at an estimated rate of 1.7 stillbirths per 1000 births. A multivariable logistic regression model will be developed in line with current Transparent Reporting of a multivariable prediction model for Individual Prognosis or Diagnosis (TRIPOD) guidelines to estimate the gestation-specific probability of stillbirth with prediction intervals. Candidate predictors were identified from systematic reviews and clinical consultation and will be described through univariable regression analysis. To generate a final model, elimination by backward stepwise multivariable logistic regression will be performed. The model will be internally validated using bootstrapping with 1000 repetitions and externally validated using a temporally unique dataset. Overall model performance will be assessed with R2, calibration, and discrimination. Calibration will be reported using a calibration plot with 95% confidence intervals (α = 0.05). Discrimination will be measured by the C-statistic and area underneath the receiver-operator curves. Clinical usefulness will be reported as positive and negative predictive values, and a decision curve analysis will be considered. DISCUSSION: A robust method to predict a pregnant woman's individualized risk of late-pregnancy stillbirth is needed to inform timely, appropriate care to reduce stillbirth. Among existing prediction models designed for obstetric use, few have been subject to internal and external validation and many fail to meet recommended reporting standards. In developing a risk prediction model for late-gestation stillbirth with both providers and pregnant women in mind, we endeavor to develop a validated model for clinical use in Australia that meets current reporting standards.

Characteristics and causes of death in children with neonatal abstinence syndrome.

AIM: To determine characteristics of death in children with neonatal abstinence syndrome (NAS). METHODS: A population-based linkage study of children from birth to 13 years of age in New South Wales (NSW), Australia, born 1 July 2000 to 31 December 2011. Infants with an International Statistical Classification of Diseases and Related Problems, Australian modification coding of NAS (P96.1, n = 3842) were compared to infants (n = 1 018 421) without NAS by birth, hospitalisation and death records linkage. RESULTS: Forty-five (1.2%) children with NAS died, compared to 3665 (0.4%) other children. Most deaths (n = 30, 66%) in NAS children occurred between 1 month and 1 year. Risk of death was independently increased in full-term children (hazard ratio 2.34, 95% confidence interval 1.63-3.35; P < 0.001) from lower socio-economic groups (1.23, 1.12-1.35; P < 0.001), most commonly from ill-defined or external causes, including assault and accidents (P < 0.001). CONCLUSIONS: Children with NAS, especially those of term gestation and from lower socio-economic groups, are more likely to die, especially from external causes.

New Australian birthweight centiles.

OBJECTIVES: To prepare more accurate population-based Australian birthweight centile charts by using the most recent population data available and by excluding pre-term deliveries by obstetric intervention of small for gestational age babies. DESIGN: Population-based retrospective observational study. SETTING: Australian Institute of Health and Welfare National Perinatal Data Collection. PARTICIPANTS: All singleton births in Australia of 23-42 completed weeks' gestation and with spontaneous onset of labour, 2004-2013. Births initiated by obstetric intervention were excluded to minimise the influence of decisions to deliver small for gestational age babies before term. MAIN OUTCOME MEASURES: Birthweight centile curves, by gestational age and sex. RESULTS: Gestational age, birthweight, sex, and labour onset data were available for 2 807 051 singleton live births; onset of labour was spontaneous for 1 582 137 births (56.4%). At pre-term gestational ages, the 10th centile was higher than the corresponding centile in previous Australian birthweight charts based upon all births. CONCLUSION: Current birthweight centile charts probably underestimate the incidence of intra-uterine growth restriction because obstetric interventions for delivering pre-term small for gestational age babies depress the curves at earlier gestational ages. Our curves circumvent this problem by excluding intervention-initiated births; they also incorporate more recent population data. These updated centile curves could facilitate more accurate diagnosis of small for gestational age babies in Australia.

Adverse perinatal outcomes in immigrants: A ten-year population-based observational study and assessment of growth charts.

BACKGROUND: Maternity populations are becoming increasingly multiethnic. Conflicting findings exist regarding the risk of adverse perinatal outcomes among immigrant mothers from different world regions and which growth charts are most appropriate for identifying the risk of adverse outcomes. OBJECTIVE: To evaluate whether infant mortality and morbidity, and the categorisation of infants as small for gestational age or large for gestational age (SGA or LGA) vary by maternal country of birth, and to assess whether the choice of growth chart alters the risk of adverse outcomes in infants categorised as SGA and LGA. METHODS: A population cohort of 601 299 singleton infants born in Australia to immigrant mothers was compared with 1.7 million infants born to Australian-born mothers, 2004-2013. Infants were categorised as SGA and LGA according to a descriptive Australian population-based birthweight chart (Australia-2012 reference) and the prescriptive INTERGROWTH-21st growth standard. Propensity score reweighting was used for the analysis. RESULTS: Compared to Australian-born infants, infants of mothers from Africa, Philippines, India, other Asia countries, and the Middle East had between 15.4% and 48.1% elevated risk for stillbirth, preterm delivery, or low Apgar score. The association between SGA and LGA and perinatal mortality varied markedly by growth chart and country of birth. Notably, SGA infants from African-born mothers had a relative risk of perinatal mortality of 6.1 (95% CI 4.3, 6.7) and 17.3 (95% CI 12.0, 25.0) by the descriptive and prescriptive charts, respectively. LGA infants born to Australian-born mothers were associated with a 10% elevated risk of perinatal mortality by the descriptive chart compared to a 15% risk reduction by the prescriptive chart. CONCLUSIONS: Country-of-birth-specific variations are becoming increasingly important for providing ethnically appropriate and safe maternity care. Our findings highlight significant variations in risk of adverse perinatal outcomes in immigrant subgroups, and demonstrate how the choice of growth chart alters the quantification of risk associated with being born SGA or LGA.

Impact of influenza on hospitalization rates in children with a range of chronic lung diseases.

BACKGROUND: Data on burden of severe influenza in children with a range of chronic lung diseases (CLDs) remain limited. METHOD: We performed a cohort study to estimate burden of influenza-associated hospitalization in children with CLDs using population-based linked data. The cohort comprised all children in New South Wales, Australia, born between 2001 and 2010 and was divided into five groups, children with: (a) severe asthma; (b) bronchopulmonary dysplasia (BPD); (c) cystic fibrosis (CF); (d) other congenital/chronic lung conditions; and (e) children without CLDs. Incidence rates and rate ratios for influenza-associated hospitalization were calculated for 2001-2011. Average cost/episode of hospitalization was estimated using public hospital cost weights. RESULTS: Our cohort comprised 888 157 children; 11 058 (1.2%) had one of the CLDs. The adjusted incidence/1000 child-years of influenza-associated hospitalization in children with CLDs was 3.9 (95% CI: 2.6-5.2) and 0.7 (95% CI: 0.5-0.9) for children without. The rate ratio was 5.4 in children with CLDs compared to children without. The adjusted incidence/1000 child-years (95% CI) in children with severe asthma was 1.1 (0.6-1.6), with BPD was 6.0 (3.7-8.3), with CF was 7.4 (2.6-12.1), and with other congenital/chronic lung conditions was 6.9 (4.9-8.9). The cost/episode (95% CI) of influenza-associated hospitalization was AUD 19 704 (95% CI: 11 715-27 693) for children with CLDs compared to 4557 (95% CI: 4129-4984) for children without. DISCUSSION: This large population-based study suggests a significant healthcare burden associated with influenza in children with a range of CLDs.

Active care of infants born between 22 and 26 weeks of gestation does not follow consensus expert recommendations.

AIM: To determine the relationship between clinical practice and publication of an Australian consensus statement for management of extremely preterm infants in 2006. METHODS: A population-based study using linked data from New South Wales, Australia for births between 22 + 0 and 26 + 6 weeks of gestation between 2000 and 2011. RESULTS: There were 4746 births of whom 2870 were liveborn and 1876 were stillborn. Of the live births, 2041 (71%) were resuscitated, 1914 (67%) were admitted into a neonatal intensive care unit (NICU) and 1310 (46%) survived to hospital discharge. Thirty-nine (2%) stillbirths were resuscitated but none survived. No 22-week infant survived to hospital discharge. Fewer 23-week gestation infants were resuscitated between 2004 (52%) and 2005 (20%) but resuscitation rates increased by 2008 (44%). There was no difference at other gestations. Adjusted odds ratio (OR) for resuscitation was increased by birthweight (OR: 1.01), tertiary hospital birth (OR: 3.4) and Caesarean delivery (OR: 11.3) and decreased by rural residence (OR: 0.4) and male gender (OR: 0.7). CONCLUSION: Expert recommendations may be shaped by clinical practice rather than the converse, especially for 23-week gestation infants. Recommendations should be revised regularly to include clinical practice changes.

Long-term outcomes after group B streptococcus infection: a cohort study.

OBJECTIVE: To describe the risk of death and hospitalisation until adolescence of children after group B streptococcus (GBS) infection during infancy. DESIGN: Population-based cohort study. SETTING: New South Wales, Australia. PATIENTS: All registered live births from 2000 to 2011. INTERVENTIONS: Comparison of long-term outcomes in children with the International Statistical Classification of Diseases and Related Health Problems-10th Revision discharge codes corresponding to GBS infections and those without. MAIN OUTCOME MEASURES: Death and hospitalisation. RESULTS: A total of 1206 (0.1%) children (936 (77.6%)≥37 weeks' gestation) were diagnosed with GBS infection. Over the study period, infection rates decreased from 2.1 (95% CI 1.8 to 2.4) to 0.7 (95% CI 0.5 to 0.9) per 1000 live births. Infants with GBS infection were born at lower gestation (mean 37.6 vs 39.0 weeks), were more likely very low birth weight (<1500 g, OR 9.1(95% CI 7.4 to 11.3)), born premature (OR 3.9(95% CI 3.4 to 4.5)) and have 5 min Apgar scores ≤5 (OR 6.7(95% CI 5.1 to 8.8)). Children with GBS had three times the adjusted odds of death (adjusted OR (AOR) 3.0(95% CI 2.1 to 4.3)) or rehospitalisations (AOR 3.1(95% CI 2.7 to 3.5)). Thirty-six (3.0%) with GBS died, with >50% of deaths occurring <28 days. Children with GBS were hospitalised more frequently (median 2 vs 1), for longer duration (mean 3.7 vs 2.2 days) and were at higher risk for problems with genitourinary (OR 3.1(95% CI 2.8 to 3.5)) and nervous (OR 2.0 (95% CI1.7 to 2.3)) systems. CONCLUSIONS: Despite decreasing GBS rates, the risk of poor health outcomes for GBS-infected children remains elevated, especially during the first 5 years. Survivors continue to be at increased risk of death and chronic conditions requiring hospitalisations, such as cerebral palsy and epilepsy.

Association of Age at First Severe Respiratory Syncytial Virus Disease With Subsequent Risk of Severe Asthma: A Population-Based Cohort Study.

OBJECTIVE: In a population-based cohort study, we determined the association between the age at first severe respiratory syncytial virus (RSV) disease and subsequent asthma. METHODS: Incidence rates and rate ratios of the first asthma-associated hospitalization after 2 years of age in children hospitalized for RSV disease at <3 months, 3 to <6 months, 6 to <12 months, and 12-24 months of age were calculated. RESULTS: The incidence of asthma-associated hospitalization per 1000 child-years among children hospitalized for RSV disease at <3 months of age was 0.5 (95% confidence interval [CI], .2-.7); at 3 to <6 months of age, 0.9 (95% CI,.5-1.3); at 6 to <12 months of age, 2.0 (95% CI, 1.4-2.7); and at 12-24 months of age, 1.7 (95% CI, 1.0-2.5). The rate ratio of hospitalization for asthma was 2-7-fold greater among children hospitalized for RSV disease at ages ≥6 months than that among those hospitalized for RSV disease at ages 0 to <6 months. CONCLUSIONS: Although the burden of RSV disease is highest in children aged <6 months, the burden of subsequent asthma is higher in children who develop RSV disease at ages ≥6 months.

Improving, but could do better: Trends in gestation-specific stillbirth in Australia, 1994-2015.

BACKGROUND: Stillbirth remains a public health concern in high-income countries. Over the past 20 years, stillbirth rates globally have shown little improvement and large disparities. The overall stillbirth rate, which measures risk among births at all gestations, masks diverging trends at different gestations. This study investigates trends over time in gestation-specific risk of stillbirth in Australia. METHODS: Analytical epidemiological study using nationally reported gestational age data for births in Australia, 1994-2015. Average annual change in gestation-specific prospective risk of stillbirth (per 1000 fetuses at risk [FAR]) was calculated among births in 1994-2009 and 2010-2015 at term (37-41 weeks) and for preterm gestational age subgroups: 28-36, 24-27, and 20-23 weeks. RESULTS: The decline in risk of stillbirth at term from 2010 to 2015 from 1.43 to 1.16 per 1000 FAR was more rapid than from 1994 to 2009; for preterm gestations from 24 to 27 weeks, there were no discernible trends; from 28 to 36 weeks, the decline between 1994 and 2009 was not sustained; among births from 20 to 23 weeks, the risk of stillbirth plateaued in 2010-2015, fluctuating around 3.3 per 1000 FAR. CONCLUSIONS: Improvement in the stillbirth rate from 28 weeks' gestation aligns with changes in other high-income countries, but more work is needed in Australia to achieve the levels of reduction seen elsewhere. Gestation-specific risk of stillbirth is more informative than the overall stillbirth rate. The message that the overall risk of stillbirth is not changing disregards gains at different stages of pregnancy.

Treatment with nitric oxide in the neonatal intensive care unit is associated with increased risk of childhood cancer.

AIM: This study aimed to determine whether neonatal intensive care therapies increase the risk of carcinogenesis in childhood. METHODS: This study used population-based data on 1 072 957 infants born in New South Wales, Australia, between 2000 and 2011 and multivariate logistic regression to examine any associations between therapies used in the neonatal intensive care unit and diagnoses of cancer until mid 2012. RESULTS: A total of 1126 of 1 072 957 (0.1%) children were diagnosed with cancer. Cancer risk was significantly increased by preterm birth (gestation <37 weeks; adjusted odds ratio (aOR) 1.3 (95% confidence interval: 1.0-1.6), birth weight ≥4 kg (aOR 1.4, 1.2-1.6) and caesarean delivery (aOR 1.2, 1.1-1.4). Extremely preterm (<28 weeks of gestation) infants were more likely to develop hepatic tumours (aOR 12.7, 3.3-48.3) than term infants. The only therapy used in the neonatal intensive care that was independently associated with an increased risk of cancer was nitric oxide (aOR 8.6, 4.3-17.4). Eight of the 790 (1%) infants treated with nitric oxide developed cancer (gestation range 30-41 weeks, age of cancer diagnosis: four months-five years). CONCLUSION: Treatment with nitric oxide was associated with a higher risk of childhood cancer. These findings require further research.

Influence of early childhood burns on school performance: an Australian population study.

OBJECTIVES: To determine the influence of burn injuries on childhood performance in national standardised curriculum-based school tests. DESIGN: Birth and health records of 977 children who were hospitalised with a burn injury between 2000 and 2006 in the state of New South Wales, Australia, were linked to performance scores in the National Assessment Program: Literacy and Numeracy test, a compulsory nationwide curriculum-based test (CBT) and compared with children who were not hospitalised for burns and who were matched for birth year, gender, gestation and socioeconomic status. MAIN OUTCOME MEASURES: Test scores in years 3 (ages 8-9), 5 (ages 10-11) and 7 (ages 13-14) in numeracy, writing, reading, spelling, grammar and punctuation. RESULTS: Mean age at first burn injury was 28 months (median: 20, range: 0-140). Children with burns were significantly more likely to have younger mothers (28.5 vs 29.6 years) (P<0.001), be indigenous (OR 2.5 (95% CI 2.1 to 3.1)) (P<0.001) and have siblings (OR 1.2 (95% CI 1.1 to 1.4)) (P<0.001). They were also less likely to meet national minimum standards in most domains of testing until year 5, even after adjustment for parental education levels, parental smoking, maternal age and indigenous status. Each 10% increase in total body surface area burnt was associated with a decrease in year 5 scores by 37.0% in numeracy and 71.9% in writing. CONCLUSIONS: Most childhood burn injuries occur before the start of formal schooling. Children who are hospitalised for burns perform more poorly in CBT even after accounting for family and socioeconomic disadvantage. Rehabilitation of children with burn injuries must address school performance to decrease any long-term negative societal impact of burns.

Gestational age-specific perinatal mortality rates for assisted reproductive technology (ART) and other births.

STUDY QUESTION: Is perinatal mortality rate higher among births born following assisted reproductive technology (ART) compared to non-ART births? SUMMARY ANSWER: Overall perinatal mortality rates in ART births was higher compared to non-ART births, but gestational age-specific perinatal mortality rate of ART births was lower for very preterm and moderate to late preterm births. WHAT IS KNOWN ALREADY: Births born following ART are reported to have higher risk of adverse perinatal outcomes compared to non-ART births. STUDY DESIGN, SIZE, DURATION: This population-based retrospective cohort study included 407 368 babies (391 952 non-ART and 15 416 ART)-393 491 singletons and 10 877 twins or high order multiples. PARTICIPANTS/MATERIALS, SETTING, METHODS: All births (≥20 weeks of gestation and/or ≥400 g of birthweight) in five states and territories in Australia during the period 2007-2009 were included in the study, using National Perinatal Data Collection (NPDC). Primary outcome measures were rates of stillbirth, neonatal and perinatal deaths. Adjusted odds ratio (AOR) and 95% confidence interval (CI) were used to estimate the likelihood of perinatal death. MAIN RESULTS AND THE ROLE OF CHANCE: Rates of multiple birth and low birthweight were significantly higher in ART group compared to the non-ART group (P < 0.01). Overall perinatal mortality rate was significantly higher for ART births (16.5 per 1000 births, 95% CI 14.5-18.6), compared to non-ART births (11.3 per 1000 births, 95% CI 11.0-11.6) (AOR 1.45, 95% CI 1.26-1.68). However, gestational age-specific perinatal mortality rate of ART births (including both singletons and multiples) was lower for very preterm (<32 weeks' gestation) and moderate to late preterm births (32-36 weeks' gestation) (AOR 0.61, 95% CI 0.53-0.70 and AOR 0.61, 95% CI 0.53-0.70, respectively) compared to non-ART births. Congenital abnormality and spontaneous preterm were the most common causes of neonatal deaths in both ART and non-ART group. LIMITATIONS, REASONS FOR CAUTION: Due to different cut-off limit for perinatal period in Australia, the results of this study should be interpreted with cautions for other countries. Australian definition of perinatal period commences at 20 completed weeks (140 days) of gestation and ends 27 completed days after birth which is different from the definition by World Health Organisation (commences at 22 completed weeks (154 days) of gestation and ends seven completed days after birth) and by Centers for Disease Control and Prevention (includes infant deaths under age 7 days and fetal deaths at 28 weeks of gestation or more). WIDER IMPLICATIONS OF THE FINDINGS: Preterm birth is the single most important contributing factor to increased risk of perinatal mortality among ART singletons compared to non-ART singletons. Further research on reducing early preterm delivery, with the aim of reducing the perinatal mortality among ART births is needed. Couples who access ART treatment should be fully informed regarding the risk of preterm birth and subsequent risk of perinatal death. STUDY FUNDING/COMPETING INTEREST(S): There was no funding associated with this study. No conflict of interest was declared.

Association between respiratory syncytial viral disease and the subsequent risk of the first episode of severe asthma in different subgroups of high-risk Australian children: a whole-of-population-based cohort study.

OBJECTIVE: To determine the contribution of respiratory syncytial virus (RSV) to the subsequent development of severe asthma in different subgroups of children at risk of severe RSV disease. SETTINGS: The study was conducted in New South Wales (NSW), Australia. PARTICIPANTS: The study comprised all children born in NSW between 2000 and 2010 with complete follow-up till 31 December 2011. The cohort was divided into three subgroups: (1) non-Indigenous high-risk children: non-Indigenous children born preterm or born with a low birth weight; (2) Indigenous children: children of mothers whose Indigenous status was recorded as Aboriginal and/or Torres Strait Islander and (3) non-Indigenous standard risk children: all other non-Indigenous term children. PRIMARY OUTCOME MEASURE: Risk of development of severe asthma in different subgroups of children who had RSV hospitalisation in the first 2 years of life compared with those who did not. DESIGN: We performed a retrospective cohort analysis using population-based linked administrative data. Extended Cox model was used to determine HR and 95% CI around the HR for first asthma hospitalisation in different subgroups of children. RESULTS: The cohort comprised 847 516 children born between 2000 and 2010. In the adjusted Cox model, the HR of first asthma hospitalisation was higher and comparable across all subgroups of children who had RSV hospitalisation compared with those who did not. The HR (95% CI) was highest in children aged 2-3 years; 4.3 (95% CI 3.8 to 4.9) for high-risk, 4.0 (95% CI 3.3 to 4.8) for Indigenous and 3.9 (95% CI 3.7 to 4.1) for non-Indigenous standard risk children. This risk persisted beyond 7 years of age. CONCLUSION: This large study confirms a comparable increased risk of first asthma hospitalisation following RSV disease in the first 2 years of life across different subgroups children at risk.

Neonatal Abstinence Syndrome and High School Performance.

BACKGROUND AND OBJECTIVES: Little is known of the long-term, including school, outcomes of children diagnosed with Neonatal abstinence syndrome (NAS) (International Statistical Classification of Disease and Related Problems [10th Edition], Australian Modification, P96.1). METHODS: Linked analysis of health and curriculum-based test data for all children born in the state of New South Wales (NSW), Australia, between 2000 and 2006. Children with NAS (n = 2234) were compared with a control group matched for gestation, socioeconomic status, and gender (n = 4330, control) and with other NSW children (n = 598 265, population) for results on the National Assessment Program: Literacy and Numeracy, in grades 3, 5, and 7. RESULTS: Mean test scores (range 0-1000) for children with NAS were significantly lower in grade 3 (359 vs control: 410 vs population: 421). The deficit was progressive. By grade 7, children with NAS scored lower than other children in grade 5. The risk of not meeting minimum standards was independently associated with NAS (adjusted odds ratio [aOR], 2.5; 95% confidence interval [CI], 2.2-2.7), indigenous status (aOR, 2.2; 95% CI, 2.2-2.3), male gender (aOR, 1.3; 95% CI, 1.3-1.4), and low parental education (aOR, 1.5; 95% CI, 1.1-1.6), with all Ps < .001. CONCLUSIONS: A neonatal diagnostic code of NAS is strongly associated with poor and deteriorating school performance. Parental education may decrease the risk of failure. Children with NAS and their families must be identified early and provided with support to minimize the consequences of poor educational outcomes.

Risk factors associated with RSV hospitalisation in the first 2†years of life, among different subgroups of children in NSW: a whole-of-population-based cohort study.

BACKGROUND: Data on risk factors for respiratory syncytial virus (RSV)-associated hospitalisation in Australian children may be informative for preventive measures. METHODS: A whole-of-population-based study was conducted to identify comparable risk factors for RSV hospitalisation in different subgroups of children aged <2 years in New South Wales. The cohort was divided into Indigenous children and high-risk and standard risk non-Indigenous children. Data on risk factors were obtained from the Perinatal Data Collection. RSV hospitalisations were ascertained from the Admitted Patient Data Collection. Adjusted HRs were calculated for each subgroup. Population-attributable risk associated with risk factors was estimated. RESULTS: Four factors were associated with increased risk of RSV hospitalisation: maternal smoking during pregnancy, male sex, multiparity and birth during the first half of the RSV season. Increase in relative socioeconomic advantage was associated with decreased risk of hospitalisation. Among high and standard risk non-Indigenous children, the hazard was approximately double for children born to multiparous women compared to those born to primiparous women and among Indigenous children the hazard was approximately double among those born during the first half of the RSV season. Maternal smoking during pregnancy was associated with a 26-45% increased risk across subgroups and accounted for 17% (95% CI 9.3% to 24%) of RSV hospitalisations in Indigenous children, 5% (95% CI 2.5% to 8%) in high-risk and 6% (95% 5% to 7%) in standard risk non-Indigenous children. DISCUSSION: Promoting avoidance of smoking during pregnancy may help in lowering the disease burden, with Indigenous children likely to benefit most.

Population-based study shows that resuscitating apparently stillborn extremely preterm babies is associated with poor outcomes.

AIM: This population-based study determined the delivery room management and outcomes of extremely preterm infants born with Apgar scores of 0. METHODS: We linked birth, neonatal intensive care unit (NICU) and death records for babies who were born between 22 + 0 and 27 + 6 weeks of gestation with a one-minute Apgar score of 0, in New South Wales, Australia, between 1998 and 2011. RESULTS: We classified 2173/2262 (96%) of infants with a one-minute Apgar score of 0 as stillborn. Resuscitation was provided for 48/89 (54%) live births and 40/2173 (2%) stillbirths. Cardiac massage was given to 44 infants, including three 22-week stillborn babies. Of the 13 live births admitted to an NICU, 11 survived to hospital discharge. Most (98%) of the 2212 deaths occurred on the first day of life. One baby who was classified as stillborn lived for 51 days. Resuscitation increased the mean (95% confidence interval) duration of survival from 1 (0-2) to 45 (0-104) hours (p < 0.001). No infant with a five-minute Apgar score of 0 survived. CONCLUSION: Clinicians resuscitated extremely preterm infants without a detectable heartbeat, even at 22 weeks of gestation. No infant survived without resuscitation or if their heartbeat was not regained by five minutes.

Preparing linked population data for research: cohort study of prisoner perinatal health outcomes.

BACKGROUND: A study of pregnancy outcomes related to pregnancy in prison in New South Wales, Australia, designed a two stage linkage to add maternal history of incarceration and serious mental health morbidity, neonatal hospital admission and infant congenital anomaly diagnosis to birth data. Linkage was performed by a dedicated state-wide data linkage authority. This paper describes use of the linked data to determine pregnancy prison exposure pregnancy for a representative population of mothers. METHODS: Researchers assessed the quality of linked records; resolved multiple-matched identities; transformed event-based incarceration records into person-based prisoner records and birth records into maternity records. Inconsistent or incomplete records were censored. Interrogation of the temporal relationships of all incarceration periods from the prisoner record with pregnancies from birth records identified prisoner maternities. Interrogation of maternities for each mother distinguished prisoner mothers who were incarcerated during pregnancy, from prisoner control mothers with pregnancies wholly in the community and a subset of prisoner mothers with maternities both types of maternity. Standard descriptive statistics are used to provide population prevalence of exposures and compare data quality across study populations stratified by mental health morbidity. RESULTS: Women incarcerated between 1998 and 2006 accounted for less than 1 % of the 404,000 women who gave birth in NSW between 2000 and 2006, while women with serious mental health morbidity accounted for 7 % overall and 68 % of prisoners. Rates of false positive linkage were within the predicted limits set by the linkage authority for non-prisoners, but were tenfold higher among prisoners (RR 9.9; 95%CI 8.2, 11.9) and twice as high for women with serious mental health morbidity (RR 2.2; 95%CI 1.9, 2.6). This case series of 597 maternities for 558 prisoners pregnant while in prison (of whom 128 gave birth in prison); and 2,031 contemporaneous prisoner control mothers is one of the largest available. CONCLUSIONS: Record linkage, properly applied, offers the opportunity to extend knowledge about vulnerable populations not amenable to standard ascertainment. Dedicated linkage authorities now provide linked data for research. The data are not research ready. Perinatal exposures are time-critical and require expert processing to prepare the data for research.

Epidemiological Evidence for a Decreasing Incidence of Neonatal Abstinence Syndrome, 2000-11.

BACKGROUND: This study analyses the incidence of Neonatal Abstinence Syndrome (NAS) in a large geographically defined population in Australia. METHOD: Database linkage analysis of all births between 2000 and 2011 in New South Wales (NSW), Australia. The diagnosis of NAS was derived from hospital coding P96.1, 'Neonatal withdrawal symptoms from maternal use of drugs of addiction'. Temporal trends were studied by comparing epoch 1 (2000-05) with epoch 2 (2006-11). The relationship with changes in maternal factors was further analysed. RESULTS: The NAS was coded in 3842 of 1 022 263 live born infants (0.38%). NAS incidence peaked at 5.07 per 1000 live births in 2002, decreasing to 3.18 in 2011 and was negatively correlated with maternal age (r = -0.7). The rate of NAS in epoch 2 (3.4 per 1000 births, 95% CI 3.28, 3.58) was significantly lower than in epoch 1 (4.1 per 1000 births, 95% CI 3.96, 4.33). Epoch 2 mothers were significantly older (mean 29.8 years vs. 28.3 years), less likely to be multiparous (OR 0.7, 95% CI 0.6, 0.9) or smoke (OR 0.4, 95% CI 0.4, 0.5). They were more likely to engage in antenatal care earlier (mean first visit: 14.1 vs. 18.9 weeks). Most infants (~80%) were born at term (>37 weeks gestation). CONCLUSION: The incidence of NAS as a discharge diagnosis has decreased in our population since 2002. Mothers are also older and engaging earlier in prenatal care. Whether these changes alter NAS presentation and diagnosis or whether pregnant women are using drugs that do not cause typical NAS (e.g. amphetamines) is uncertain and requires further study.

Australian national birthweight percentiles by sex and gestational age for twins, 2001-2010.

BACKGROUND: Birthweight remains one of the strongest predictors of perinatal mortality and disability. Birthweight percentiles form a reference that allows the detection of neonates at higher risk of neonatal and postneonatal morbidity. The aim of the study is to present updated national birthweight percentiles by gestational age for male and female twins born in Australia. METHODS: Population data were extracted from the Australian National Perinatal Data Collection for twins born in Australia between 2001 and 2010. A total of 43,833 women gave birth to 87,666 twins in Australia which were included in the study analysis. Implausible birthweights were excluded using Tukey's methodology based on the interquartile range. Univariate analysis was used to examine the birthweight percentiles for liveborn twins born between 20 and 42 weeks gestation. RESULTS: Birthweight percentiles by gestational age were calculated for 85,925 live births (43,153 males and 42,706 females). Of these infants, 53.6% were born preterm (birth before 37 completed weeks of gestation) while 50.2% were low birthweight (<2500 g) and 8.7% were very low birthweight (<1500 g). The mean birthweight decreased from 2462 g in 2001 to 2440 g in 2010 for male twins, compared with 2485 g in 1991-94. For female twins, the mean birthweight decreased from 2375 g in 2001 to 2338 g in 2010, compared with 2382 g in 1991-94. CONCLUSIONS: The birthweight percentiles provide clinicians and researchers with up-to-date population norms of birthweight percentiles for twins in Australia.

Reasons for Rehospitalization in Children Who Had Neonatal Abstinence Syndrome.

BACKGROUND AND OBJECTIVES: Neonatal abstinence syndrome (NAS) occurs after in utero exposure to opioids, but outcomes after the postnatal period are unclear. Our objectives were to characterize childhood hospitalization after NAS. METHODS: Population-based linkage study of births, hospitalization, and death records of all children registered in New South Wales (NSW), Australia, between 2000 and 2011 to a maximum of 13 years. Infants with an International Statistical Classification of Disease and Related Problems, 10th Edition, Australian Modification, coding of NAS (P96.1, n = 3842) were compared with 1,018,421 live born infants without an NAS diagnosis. RESULTS: Infants with NAS were more likely to be admitted into a nursery (odds ratio 15.6, 95% confidence interval: 14.5-16.8) and be hospitalized longer (10.0 vs 3.0 days). In childhood, they were more likely to be rehospitalized (1.6, 1.5-1.7), die during hospitalization (3.3, 2.1-5.1), and be hospitalized for assaults (15.2, 11.3-20.6), maltreatment (21.0, 14.3-30.9), poisoning (3.6, 2.6-4.8), and mental/behavioral (2.6, 2.1-3.2) and visual (2.9, 2.5-3.5) disorders. Mothers of infants with NAS were more likely to be Indigenous (6.4, 6.0-7.0), have no antenatal care (6.6, 5.9-7.4), and be socioeconomically deprived (1.6, 1.5-1.7). Regression analyses demonstrated that NAS was the most important predictor of admissions for maltreatment (odds ratio 4.5, 95% confidence interval: 3.4-6.1) and mental and behavioral disorders (2.3, 1.9-2.9), even after accounting for prematurity, maternal age, and Indigenous status. CONCLUSIONS: Children with NAS are more likely to be rehospitalized during childhood for maltreatment, trauma, and mental and behavioral disorders even after accounting for prematurity. This continues to adolescence and emphasizes the critical need for continued support of this vulnerable group after resolution of NAS.