Hospitalisation for bronchiolitis in infants is more common after elective caesarean delivery

Association of cesarean section and infectious outcomes among infants at 1 year of age: Logistic regression analysis using data of 104,065 records from the Japan Environment and Children's Study

BACKGROUND

There has been a recent decrease in the prevalence of infectious diseases in children worldwide due to the usage of vaccines. However, the association between cesarean delivery and infectious diseases remains unclear. Here, we aimed to clarify the association between cesarean delivery and the development of infectious diseases.

METHODS

This study is a cross-sectional study. We used data from the Japan Environment and Children's Study, which is a prospective, nationwide, government-funded birth cohort study. The data of 104,065 records were included. Information about the mode of delivery, central nervous system infection (CNSI), otitis media (OM), upper respiratory tract infection (URTI), lower respiratory tract infection (LRTI), gastrointestinal infection (GI), and urinary tract infection (UTI) was obtained from questionnaires and medical records transcripts. Multiple logistic regression analysis was used to assess the association between cesarean delivery and CNSI, OM, URTI, LRTI, GI, and UTI risk.

RESULTS

We included a total of 74,477 subjects in this study, of which 18.4% underwent cesarean deliveries. After adjusting for the perinatal, socioeconomic, and postnatal confounding factors, children born by cesarean delivery did not have an increased risk of developing CNSI (95% confidence interval [CI] 0.46-1.35), OM (95% CI 0.99-1.12), URTI (95% CI 0.97-1.06), LRTI (95% CI 0.98-1.15), GI (95% CI 0.98-1.11), or UTI (95% CI 0.95-1.45).

CONCLUSIONS

This nationwide cohort study did not find an association between cesarean delivery and CNSI, OM, URTI, LRTI, GI, and UTI. However, further studies are needed to evaluate the role of cesarean delivery in the development of infectious diseases.

RNA-Sequencing Reveals Gene Expression and Pathway Signatures in Umbilical Cord Blood Affected by Birth Delivery Mode

Cesarean section (CS) confers increased risk of type I diabetes, asthma, inflammatory bowel disease, celiac disease, overweight and obesity, etc., in the offspring. However, the underlying mechanism remains unknown. To investigate the influence of CS on gene expression in cord blood, we have performed RNA-sequencing followed by single-gene analysis, gene set enrichment analysis, gene co-expression network analysis, and interacting genes/proteins analysis in eight full-term infants born by elective CS and eight matched vaginally delivered (VD) infants. Crucial genes identified above were further validated in another 20 CS and 20 VD infants. We found for the first time that mRNA expression of genes involved in immune response (IL12A, INFG, IL1B, TNF, MIF, IL4, CA1, IFI27, HLA-DOB and EPHB1) and metabolism (DLK1, CYP2A6 and GATM) were significantly influenced by CS. Notably, serum TNF-α and IFN-γ were remarkably up-regulated in the CS infants (p = 5.0 × 10-4 and 3.0 × 10-3, respectively) compared to the VD infants. It is biologically plausible that CS may exert adverse impacts on offspring health through influencing expression of genes in the above processes. These findings will help understand the potential underlying mechanisms of the adverse health impacts of CS and identify biomarkers for future health of offspring born with different delivery modes.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43657-022-00086-7.

Human matters in asthma: Considering the microbiome in pulmonary health

Microbial communities form an important symbiotic ecosystem within humans and have direct effects on health and well-being. Numerous exogenous factors including airborne triggers, diet, and drugs impact these established, but fragile communities across the human lifespan. Crosstalk between the mucosal microbiota and the immune system as well as the gut-lung axis have direct correlations to immune bias that may promote chronic diseases like asthma. Asthma initiation and pathogenesis are multifaceted and complex with input from genetic, epigenetic, and environmental components. In this review, we summarize and discuss the role of the airway microbiome in asthma, and how the environment, diet and therapeutics impact this low biomass community of microorganisms. We also focus this review on the pediatric and Black populations as high-risk groups requiring special attention, emphasizing that the whole patient must be considered during treatment. Although new culture-independent techniques have been developed and are more accessible to researchers, the exact contribution the airway microbiome makes in asthma pathogenesis is not well understood. Understanding how the airway microbiome, as a living entity in the respiratory tract, participates in lung immunity during the development and progression of asthma may lead to critical new treatments for asthma, including population-targeted interventions, or even more effective administration of currently available therapeutics.

Socioeconomic position, bronchiolitis and asthma in children: counterfactual disparity measures from a national birth cohort study

BACKGROUND

The debated link between severe respiratory syncytial virus (RSV) infection in early life and asthma has yet to be investigated within a social inequity lens. We estimated the magnitude of socioeconomic disparity in childhood asthma which would remain if no child were admitted to hospital for bronchiolitis, commonly due to RSV, during infancy.

METHODS

The cohort, constructed from national administrative health datasets, comprised 83853 children born in Scotland between 1 January 2007 and 31 June 2008. Scottish Index for Multiple Deprivation (SIMD) was used to capture socioeconomic position. Emergency admissions for bronchiolitis before age 1 year were identified from hospital records. Yearly indicators of asthma/wheeze from ages 2 to 9 years were created using dispensing data and hospital admission records.

RESULTS

Using latent class growth analysis, we identified four trajectories of asthma/wheeze: early-transient (2.2% of the cohort), early-persistent (2.0%), intermediate-onset (1.8%) and no asthma/wheeze (94.0%). The estimated marginal risks of chronic asthma (combining early-persistent and intermediate-onset groups) varied by SIMD, with risk differences for the medium and high deprivation groups, relative to the low deprivation group, of 7.0% (95% confidence interval: 3.7-10.3) and 13.0% (9.6-16.4), respectively. Using counterfactual disparity measures, we estimated that the elimination of bronchiolitis requiring hospital admission could reduce these risk differences by 21.2% (4.9-37.5) and 17.9% (10.4-25.4), respectively.

CONCLUSIONS

The majority of disparity in chronic asthma prevalence by deprivation level remains unexplained. Our paper offers a guide to using causal inference methods to study other plausible pathways to inequities in asthma using complex, linked administrative data.

Association Between Mode of Delivery of the Breech Fetus and Hospitalizations Due to Inflammatory Bowel Disease During Childhood

BACKGROUND AND GOALS

While evidence suggests short-term benefits in neonatal morbidity and mortality from cesarean delivery of the fetus in breech presentation, the long-term implications for the offspring are less clear. To assess the implications of the mode of delivery on offspring's health, we have evaluated the long-term gastrointestinal (GI) morbidity of offspring with a breech presentation delivered in either way.

MATERIALS AND METHODS

A population-based retrospective cohort study including singleton deliveries in breech presentation occurring between 1991 and 2014 at a tertiary referral hospital. Incidence of hospitalizations of the offspring up to the age of 18 years involving GI morbidity was compared between those delivered via cesarean section or vaginally. A Kaplan-Meier survival curve compared cumulative GI morbidity. A Weibull parametric survival model controlled for confounders while accounting for repeated occurrence of mothers and dependence among siblings.

RESULTS

Overall, 86.9% (n=6376) of the 7337 fetuses in breech presentation, were delivered abdominally. Hospitalizations involving GI morbidity were higher in offspring delivered by cesarean section, specifically due to inflammatory bowel disease (IBD). Kaplan-Meier survival curve revealed the higher cumulative incidence of total GI morbidity and IBD specifically in the cesarean delivery group (P<0.001 and P=0.004, respectively). Using a Weibull parametric while controlling for relevant confounders, cesarean delivery emerged as an independent risk factor for long-term IBD-related morbidity of the offspring delivered in breech presentation (adjusted hazard ratio=3.18, 95% confidence interval: 1.47-6.87, P=0.003).

CONCLUSION

Cesarean delivery is associated with higher rates of hospitalizations due to IBD and total GI morbidity during childhood in term singleton in breech presentation.

Early-life viral infections are associated with disadvantageous immune and microbiota profiles and recurrent respiratory infections

The respiratory tract is populated by a specialized microbial ecosystem, which is seeded during and directly following birth. Perturbed development of the respiratory microbial community in early-life has been associated with higher susceptibility to respiratory tract infections (RTIs). Given a consistent gap in time between first signs of aberrant microbial maturation and the observation of the first RTIs, we hypothesized that early-life host-microbe cross-talk plays a role in this process. We therefore investigated viral presence, gene expression profiles and nasopharyngeal microbiota from birth until 12 months of age in 114 healthy infants. We show that the strongest dynamics in gene expression profiles occurred within the first days of life, mostly involving Toll-like receptor (TLR) and inflammasome signalling. These gene expression dynamics coincided with rapid microbial niche differentiation. Early asymptomatic viral infection co-occurred with stronger interferon activity, which was related to specific microbiota dynamics following, including early enrichment of Moraxella and Haemophilus spp. These microbial trajectories were in turn related to a higher number of subsequent (viral) RTIs over the first year of life. Using a multi-omic approach, we found evidence for species-specific host-microbe interactions related to consecutive susceptibility to RTIs. Although further work will be needed to confirm causality of our findings, together these data indicate that early-life viral encounters could impact subsequent host-microbe cross-talk, which is linked to later-life infections.

nnLong-Term Respiratory Outcomes in Early Term Born Offspring: A Systematic Review and Meta-Analysis

OBJECTIVE

Newborns exhibit the lowest immediate respiratory morbidity rates when born at full term (39-40) completed weeks of gestation. We evaluated whether early-term deliveries (37^0/7-38^6/7 weeks of gestation) bare a significant impact on overall and specific long-term respiratory outcomes of offspring up to the age of 18 years, as compared to offspring born at full term or later.

DATA SOURCES

PubMed/Medline, EMBASE, and relevant reference lists from January 2012 to May 2020.

STUDY ELIGIBILITY CRITERIA

This systematic review and meta-analysis was conducted according to the PRISMA guidelines and was registered in PROSPERO. Any observational or randomized human trials addressing the association between early term delivery and long-term respiratory outcomes in the offspring, restricted to studies published in English, were included. Search included terms relating to gestational age, pediatric morbidity, and respiratory outcomes. We included studies assessing long term respiratory disease (1-18 years) of offspring born during early term as compared to full term and later.

STUDY APPRAISAL AND SYNTHESIS METHODS

Two independent reviewers extracted data and assessed risk of bias. Using a random-effect meta-analysis, pooled relative risk with their 95% confidence intervals and heterogeneity were determined. Publication bias was assessed by Funnel plots with Eggers regression line and contours, and sensitivity analyses were performed using Baujat plots.

RESULTS

Fourteen studies were included following a screen of nearly 2500 abstracts. These studies included nearly eight million patients, and were subjected to qualitative and quantitative analyses. Early term delivery significantly increased the risk of total respiratory morbidity in the offspring (RR= 1.20, 95% CI= 1.16, 1.26) as compared to full term delivery. The increased respiratory morbidity was attributed to obstructive airway diseases (RR=1.19, 95% CI= 1.12, 1.27) and infectious respiratory diseases (RR= 1.22, 95% CI= 1.17, 1.29). Most studies were of acceptable quality.

CONCLUSION

This comprehensive meta-analysis suggests that early term delivery poses a risk for long term pediatric respiratory morbidity, as compared to full term delivery. Notably, other factors over the years cannot be accounted for. This adds an important perspective to be considered when balancing the fetal, maternal, and neonatal risks associated with delivery timing.

Racial/Ethnic Disparities in the Incidences of Bronchiolitis Requiring Hospitalization

BACKGROUND

Race/ethnicity is currently not considered a risk factor for bronchiolitis, except for indigenous populations in Western countries. A better understanding of the potential impact of race/ethnicity can inform programs, policies, and practices related to bronchiolitis.

METHODS

We performed a population-based, longitudinal, observational study using the State Inpatient Database from New York State in the United States. Infants born between 2009 and 2013 at term without comorbidities were followed for the first 2 years of life, up to 2015. We calculated the cumulative incidences among different race/ethnicity groups, and evaluated the risks by developing logistic regression models.

RESULTS

Of 877 465 healthy, term infants, 10 356 infants were hospitalized with bronchiolitis. The overall cumulative incidence was 11.8 per 1000 births. The cumulative incidences in non-Hispanic White, non-Hispanic Black, Hispanic, and Asian infants were 8.6, 15.4, 19.1, and 6.5 per 1000 births, respectively. In a multivariable analysis adjusting for socioeconomic status, the risks remained substantially high among non-Hispanic Black (odds ratio, 1.42; 95% confidence interval [CI], 1.34-1.51) and Hispanic infants (odds ratio, 1.77; 95% CI, 1.67-1.87), whereas being of Asian race was protective (odds ratio, .62; 95% CI, .56-.69).

CONCLUSIONS

The risks of bronchiolitis hospitalization in the first 2 years of life were substantially different by race/ethnicity, with Hispanic and Black infants having the highest rates of hospitalization. Further research is needed to develop and implement culturally appropriate public health interventions to reduce racial and ethnic health disparities in bronchiolitis.

Association of Cesarean Delivery with Childhood Hospitalization for Infections Before 13 Years of Age

OBJECTIVES

To determine the association between cesarean delivery and childhood infections up to 13 years of age.

STUDY DESIGN

We conducted a longitudinal cohort study of 731 803 children born between 2006 and 2016 at all hospitals in the province of Quebec, Canada. We followed children born by cesarean, operative vaginal, and nonoperative vaginal delivery up to 13 years of age. Outcomes included hospitalization for otitis media, respiratory, infectious enteritis, and other infections. We estimated hazard ratios with 95% CIs for the association between mode of delivery and childhood infections, adjusted for patient characteristics.

RESULTS

At age 3-4 years, cesarean delivery was associated with a 1.07-fold greater risk of otitis media (95% CI, 1.03-1.11), a 1.15-fold greater risk of respiratory infection (95% CI, 1.09-1.22), and a 1.13-fold greater risk of infectious enteritis (95% CI, 1.03-1.25) compared with nonoperative vaginal delivery. However, operative vaginal delivery was associated with these same outcomes. Both cesarean and operative vaginal delivery were more strongly associated with infection hospitalization before age 1 year, but associations disappeared after 5 years.

CONCLUSIONS

Cesarean delivery is associated with infection hospitalization before but not after age 5 years. However, associations were also present for operative vaginal delivery, which suggests that mechanisms other than exposure to maternal vaginal flora explain the relationship.

Caesarean section and severe upper and lower respiratory tract infections during infancy: Evidence from two UK cohorts

BACKGROUND

Several studies have reported that birth by caesarean section is associated with increased risk of lower respiratory tract infections in the child, but it is unclear whether this applies to any caesarean section or specifically to planned caesareans. Furthermore, although infections of the upper respiratory tract are very common during childhood, there is a scarcity of studies examining whether caesarean is also a risk factor for this site of infection.

METHODS

We obtained data from two UK cohorts: the Millennium Cohort Study (MCS) and linked administrative datasets of the population of Wales through the Secure Anonymised Information Linkage (SAIL) databank. The study focused on term-born singleton infants and included 15,580 infants born 2000-2002 (MCS) and 392,145 infants born 2002-2016 (SAIL). We used information about mode of birth (vaginal delivery, assisted vaginal delivery, planned caesarean and emergency caesarean) from maternal report in the MCS and from hospital birth records in SAIL. Unplanned hospital admission for lower respiratory tract infection (LRTI) was ascertained from maternal report in the MCS and from hospital record ICD codes in SAIL. Information about admissions for upper respiratory tract infection (URTI) was available from SAIL only. Cox regression was used to estimate hazard ratios for each outcome and cohort separately while accounting for a wide range of confounders. Gestational age at birth was further examined as a potential added, indirect risk of planned caesarean birth due to the early delivery.

FINDINGS

The rate of hospital admission for LRTI was 4.6 per 100 child years in the MCS and 5.9 per 100 child years in SAIL. Emergency caesarean was not associated with LRTI admission during infancy in either cohort. In the MCS, planned caesarean was associated with a hazard ratio of 1.39 (95% CI 1.03, 1.87) which further increased to 1.65 (95% CI 1.24, 2.19) when gestational age was not adjusted for. In SAIL, the adjusted hazard ratio was 1.10 (95% CI 1.05, 1.15), which increased to 1.17 (95% CI 1.12, 1.22) when gestational age was not adjusted for. The rate of hospital admission for URTI was 5.9 per 100 child years in SAIL. Following adjustments, emergency caesarean was found to have a hazard ratio of 1.09 (95% CI 1.05, 1.14) for hospital admission for URTI. Planned caesarean was associated with a hazard ratio of 1.11 (95% CI 1.06, 1.16) which increased to 1.17 (95% CI 1.12, 1.22) when gestational age was not adjusted for.

CONCLUSIONS

The risk of severe LRTIs during infancy is moderately elevated in infants born by planned caesarean compared to those born vaginally. Infants born by any type of caesarean may also be at a small increased risk of severe URTIs. The estimated effect sizes are stronger if including the indirect effect arising from planning the caesarean birth for an earlier gestation than would have occurred spontaneously. Further studies are needed to confirm these results.

Elective caesarean section and bronchiolitis hospitalization: A retrospective cohort study

BACKGROUND

We sought to evaluate whether elective caesarean section is associated with subsequent hospitalization for bronchiolitis.

METHODS

This is a retrospective cohort study that used the electronic medical record database of Clalit Health Services, the largest healthcare fund in Israel, serving over 4.5 million members and over half of the total population. The primary outcome was bronchiolitis admission in the first 2 years of life. We performed logistic regression analyses to identify independent associations. We repeated the analysis using boosted decision tree machine learning techniques to confirm our findings.

RESULTS

There were 124 553 infants enrolled between 2008 and 2010, and 5168 (4.1%) were hospitalized for bronchiolitis in the first 2 years of life. In logistic regression models stratified by seasons, elective caesarean section birth was associated with 15% increased odds (95% CI: 1.02-1.30) for infants born in the fall season, 28% increased odds (95% CI: 1.11, 1.47) for those born in the winter, 35% increased odds (95% CI: 1.12-1.62) for those born in the spring and 37% increased odds (95% CI: 1.18-1.60) for those born in the summer. In the boosted gradient decision tree analysis, the area under the curve for risk of bronchiolitis admission was 0.663 (95% CI: 0.652, 0.674) with timing of birth as the most important feature.

CONCLUSION

Elective caesarean section, a potentially modifiable risk factor, is associated with increased odds of hospitalization for bronchiolitis in the first 2 years of life. These data should be considered when scheduling elective caesarean sections especially for infants born in spring and summer months.

Mode of birth and risk of infection-related hospitalisation in childhood: A population cohort study of 7.17 million births from 4 high-income countries

BACKGROUND

The proportion of births via cesarean section (CS) varies worldwide and in many countries exceeds WHO-recommended rates. Long-term health outcomes for children born by CS are poorly understood, but limited data suggest that CS is associated with increased infection-related hospitalisation. We investigated the relationship between mode of birth and childhood infection-related hospitalisation in high-income countries with varying CS rates.

METHODS AND FINDINGS

We conducted a multicountry population-based cohort study of all recorded singleton live births from January 1, 1996 to December 31, 2015 using record-linked birth and hospitalisation data from Denmark, Scotland, England, and Australia (New South Wales and Western Australia). Birth years within the date range varied by site, but data were available from at least 2001 to 2010 for each site. Mode of birth was categorised as vaginal or CS (emergency/elective). Infection-related hospitalisations (overall and by clinical type) occurring after the birth-related discharge date were identified in children until 5 years of age by primary/secondary International Classification of Diseases, 10th Revision (ICD-10) diagnosis codes. Analysis used Cox regression models, adjusting for maternal factors, birth parameters, and socioeconomic status, with results pooled using meta-analysis. In total, 7,174,787 live recorded births were included. Of these, 1,681,966 (23%, range by jurisdiction 17%-29%) were by CS, of which 727,755 (43%, range 38%-57%) were elective. A total of 1,502,537 offspring (21%) had at least 1 infection-related hospitalisation. Compared to vaginally born children, risk of infection was greater among CS-born children (hazard ratio (HR) from random effects model, HR 1.10, 95% confidence interval (CI) 1.09-1.12, p < 0.001). The risk was higher following both elective (HR 1.13, 95% CI 1.12-1.13, p < 0.001) and emergency CS (HR 1.09, 95% CI 1.06-1.12, p < 0.001). Increased risks persisted to 5 years and were highest for respiratory, gastrointestinal, and viral infections. Findings were comparable in prespecified subanalyses of children born to mothers at low obstetric risk and unchanged in sensitivity analyses. Limitations include site-specific and longitudinal variations in clinical practice and in the definition and availability of some data. Data on postnatal factors were not available.

CONCLUSIONS

In this study, we observed a consistent association between birth by CS and infection-related hospitalisation in early childhood. Notwithstanding the limitations of observational data, the associations may reflect differences in early microbial exposure by mode of birth, which should be investigated by mechanistic studies. If our findings are confirmed, they could inform efforts to reduce elective CS rates that are not clinically indicated.

Is socioeconomic position associated with bronchiolitis seasonality? A cohort study

BACKGROUND

Understanding differences in the seasonality of bronchiolitis can help to plan the timing of interventions. We quantified the extent to which seasonality in hospital admissions for bronchiolitis is modified by socioeconomic position.

METHODS

Using Hospital Episode Statistics, we followed 3 717 329 infants born in English National Health Service hospitals between 2011 and 2016 for 1 year. We calculated the proportion of all infant admissions due to bronchiolitis and the incidence rate of bronchiolitis admissions per 1000 infant-years, according to year, month, age, socioeconomic position and region. We used harmonic Poisson regression analysis to assess whether socioeconomic position modified bronchiolitis seasonality.

RESULTS

The admission rate for bronchiolitis in England increased from 47.4 (95% CI 46.8 to 47.9) to 58.9 per 1000 infant-years (95% CI 58.3 to 59.5) between 2012 and 2016. We identified some variation in the seasonality of admissions by socioeconomic position: increased deprivation was associated with less seasonal variation and a slightly delayed epidemic peak. At week 50, the risk of admission was 38% greater (incidence rate ratios 1.38; 95% CI 1.35 to 1.41) for infants in the most deprived socioeconomic group compared with the least deprived group.

CONCLUSION

These results do not support the need for differential timing of prophylaxis or vaccination by socioeconomic group but suggest that infants born into socioeconomic deprivation should be considered a priority group for future interventions. Further research is needed to establish if the viral aetiology of bronchiolitis varies by season and socioeconomic group, and to quantify risk factors mediating socioeconomic deprivation and bronchiolitis rates.

Delivery mode and future infectious morbidity of the offspring: a sibling analysis

PURPOSE

Cesarean delivery (CD) has been recently suggested to be associated with offspring's long-term health implications. We aimed to investigate the association between delivery mode and long-term infectious morbidity of the offspring while employing sibling matched analysis to maximize confounder control.

METHODS

A retrospective population-based cohort study was performed, which included all sibling deliveries occurring between 1991 and 2014 at a regional tertiary medical center. Offsprings were followed up until the age of 18 years. The study included 13,516 individuals (6758 sibling pairs): the first born was via vaginal delivery and the second via CD. Each siblings pair was considered a matched set, with the aim to perform a within-family analysis. A Kaplan-Meier survival curve was used to compare the cumulative infectious morbidity incidence and a multivariable Cox survival hazards regression model to control for confounders.

RESULTS

Crude rates of total infectious hospitalizations were found to be significantly higher in the CD group (OR 1.25; 95% CI 1.12-1.40). Specifically, bronchiolitis (OR 2.02, 95% CI 1.56-2.63), otitis (OR 1.52, 95% CI 1.21-1.9), and gastroenteritis (OR 1.41, 95% CI 1.05-1.9) were all found to be significantly more common in the CD group. The survival curve demonstrated significantly higher cumulative infection-related hospitalization rates in the CD group (log-rank p < 0.001). The Cox model, adjusted for several confounders, confirmed the significant association between CD and offspring's infection-related morbidity (adjusted HR 1.25; 95% CI 1.02-1.53).

CONCLUSION

CD appears to be independently associated with later offspring infection-related morbidity, even while rigorously adjusting for confounders.

Hospital admissions for lower respiratory tract infections after early-, late-, and post-term birth

BACKGROUND

Recent data suggest that early-term births are associated with later respiratory morbidity (LRTI), and post-term births may decrease this risk.

OBJECTIVES

The objective was to determine the impact of early-term, late-term, and post-term birth on hospital admission for LRTI up to the age of seven years. Additionally, we explored maternal and perinatal factors associated with the risk of admission for LRTIs.

METHODS

The association of early-term (37⁺⁰ -38⁺⁶  weeks), late-term (41⁺⁰ -41⁺⁶  weeks), and post-term (≥42 weeks) birth with hospital admissions for lower respiratory tract infections (LRTI) in comparison with infants born full-term (39⁺⁰ -40⁺⁶  weeks) was assessed and early predictors of LRTI were established. The register study included 948 695 infants born in Finland in 1991-2008. Data were analysed in four-term subgroups. Hospital admissions for bronchiolitis/bronchitis and pneumonia were collected up to 7 years of age. Adjusted Cox proportional hazards models were used to assess risk factors of LRTI admissions.

RESULTS

The rates of hospital admission in the early-, full-, late-, and post-term groups were 6.7%, 5.5%, 5.1%, and 4.8% for bronchiolitis/bronchitis, and 2.8%, 2.4%, 2.3%, and 2.3% for pneumonia. Early-term birth was associated with an increased risk of admission for bronchiolitis/bronchitis (hazard ratio HR 1.21, 95% confidence interval CI 1.18, 1.23) and pneumonia (HR 1.16, 95% CI 1.12, 1.20), while late-term (HR 0.93, 95% CI 0.91, 0.95) and post-term births (HR 0.89, 95% CI 0.85, 0.93) were associated with a decreased risk of bronchiolitis/bronchitis admission compared with the full-term group. Maternal age ≤ 20 years, smoking during pregnancy, male sex, caesarean delivery, small for gestational age, 1-minute Apgar score < 4, ventilator support, and neonatal antibiotic therapy were associated with an increased risk of LRTI admission, while being firstborn, born in a level-II hospital and in the Northern region was associated with decreased risk.

CONCLUSION

Early-term birth was associated with a higher risk of all LRTI admissions while late-term and post-term births were associated with lower risk of bronchiolitis/bronchitis admission. Modifiable risk factors of LRTIs were smoking during pregnancy, birth by elective caesarean delivery, neonatal ventilator support, and antibiotic therapy.

Association Between Mode of Delivery and Risk of Infection in Early Childhood: A Cohort Study

BACKGROUND

Infections are the leading cause of morbidity and mortality in children. Caesarean section as a potential risk factor for infection has recently gained interest. Delivery by caesarean section has increased greatly, with nonmedical reasons playing an increasing role. We aimed to analyze the association between mode of delivery and hospitalizations because of infection and symptoms of infection at home in early childhood.

METHODS

A cohort study, based on the Odense Child Cohort, following infants from gestation until a mean age of 3.5 years. Data on hospitalization because of infections were collected from the Danish National Patient Registry. Data on symptoms of infection at home were collected via a text message-based questionnaire.

RESULTS

A total of 1921 children were born by vaginal delivery, 283 by elective caesarean section and 227 by acute caesarean section. An adjusted regression model showed an incidence rate ratio for hospitalizations because of infection in children born by elective caesarean section compared with children born by vaginal delivery of 1.45 (95% confidence interval: 1.16-1.80; P = 0.001). The analyses on symptoms of infection at home found no associations between any symptom of infection and mode of delivery. Symptom-specific subanalyses showed contrasting results.

CONCLUSIONS

Mode of delivery showed a strong association to hospitalization because of infectious disease during early childhood. Overall, no association was present between rate of symptoms of infection at home and mode of delivery.

Risk factors for severe bronchiolitis caused by respiratory virus infections among Mexican children in an emergency department

Severe bronchiolitis is the most common reason for hospitalization among children younger than 2 years. This study analyzed the prevalence of community-acquired respiratory virus infection and the risk factors for hospitalization of Mexican children with severe bronchiolitis treated in an Emergency department.This retrospective study included 134 children 2 years or younger with severe viral bronchiolitis, and 134 healthy age-matched controls. The study period was September 2012 to January 2015. We determined the viral etiology and coinfections with multiple viruses and compared the risk factors detected in children with severe viral bronchiolitis with those in the control group.A total of 153 respiratory viruses in these 134 patients, single or mixed infections, were identified: respiratory syncytial virus (RSV) type A or B was the most frequently detected (23.6% and 17.6%, respectively), followed by rhinovirus (RV; 16.3%) and parainfluenza virus (PIV) type 3 (12.4%). Coinfections of 2 respiratory viruses were found in 14.2% of cases; all cases had either RSV type A or B with another virus, the most common being parainfluenza virus or rhinovirus. Exposure to cigarette smoking was independently associated with hospitalization for severe bronchiolitis (OR, 3.5; 95% CI, 1.99-6.18; P = .0001), and having completed the vaccination schedule for their age was a protective factor against adverse outcome (OR, 0.55; 95% CI, 0.35-0.87; P = .010).RSV is a common infection among young children with severe bronchiolitis; thus, developing a vaccine against RSV is essential. Campaigns to reinforce the importance of avoiding childhood exposure to cigarette smoke are also needed.

Early-Life Host-Microbiome Interphase: The Key Frontier for Immune Development

Human existence can be viewed as an "animal in a microbial world." A healthy interaction of the human host with the microbes in and around us heavily relies on a well-functioning immune system. As development of both the microbiota and the host immune system undergo rapid changes in early life, it is not surprising that even minor alterations during this co-development can have profound consequences. Scrutiny of existing data regarding pre-, peri-, as well as early postnatal modulators of newborn microbiota indeed suggest strong associations with several immune-mediated diseases with onset far beyond the newborn period. We here summarize these data and extract overarching themes. This same effort in turn sets the stage to guide effective countermeasures, such as probiotic administration. The objective of our review is to highlight the interaction of host immune ontogeny with the developing microbiome in early life as a critical window of susceptibility for lifelong disease, as well as to identify the enormous potential to protect and promote lifelong health by specifically targeting this window of opportunity.

Using record linkage to examine testing patterns for respiratory viruses among children born in Western Australia

Changes in respiratory pathogen testing can affect disease burden estimates. Using linked data, we describe changes in respiratory virus testing among children born in Western Australia in 1996-2012. We extracted data on respiratory specimens from these children from birth to age 9 years. We estimated testing rates by age, year, Aboriginal status and geographical location. Predictors of testing among children hospitalised at least once before their 10th birthday were identified using logistic regression. We compared detection methods for respiratory viruses from nasal/nasopharyngeal (NP) specimens by age and year. Of 83 199 virology testing records in 2000-2012, 80% were nasal/NP specimens. Infants aged <1 month had the highest testing rates. Testing rates in all children increased over the study period with considerable yearly fluctuations. Among hospitalised children, premature children <32 weeks gestation had over three times the odds of being tested (95% CI 3·47-4·13) than those born at term. Testing using molecular methods increased from 5% to 87% over the study period. Proportion of positive samples increased from 36·3% to 44·4% (P < 0·01); this change was greatest in children aged 2-9 years. These findings will assist in interpreting results from future epidemiology studies assessing the pathogen-specific burden of disease.

Pre-birth cohort study of atopic dermatitis and severe bronchiolitis during infancy

BACKGROUND

Infants hospitalized for bronchiolitis (i.e. severe bronchiolitis) are at increased risk of childhood asthma. There are many known risk factors for severe bronchiolitis, including cardiac and pulmonary diseases. Less is known about the association between atopic diseases and risk of severe bronchiolitis. We sought to further examine risk factors for severe bronchiolitis, focusing on atopic dermatitis (AD).

METHODS

We conducted a nested cohort study within the Massachusetts General Hospital Obstetric Maternal Study (MOMS), a prospective cohort of pregnant women enrolled during 1998-2006. Children of mothers enrolled in MOMS were included in the analysis if they received care within our health system (n = 5407). Potential risk factors for bronchiolitis and hospitalization data were extracted from the children's electronic health records; we also examined pregnancy and perinatal risk factors collected from the underlying MOMS data.

RESULTS

During the first year of life, 125 infants (2.3%) had severe bronchiolitis. Eighteen of these patients had AD; 11 (61%) were diagnosed with AD prior to bronchiolitis hospitalization. In unadjusted analyses, AD was associated with severe bronchiolitis (χ(2) 14.6; p < 0.001). In multivariable analyses adjusting for nine known risk factors for severe bronchiolitis, including demographics, birth season, disposition at birth, cardiac disease, maternal parity, and delivery mode, AD was associated with increased odds of severe bronchiolitis (odds ratio 2.72, 95% confidence interval 1.60-4.63).

CONCLUSIONS

Atopic dermatitis is significantly associated with severe bronchiolitis in infancy. The mechanism of the AD-bronchiolitis association is unclear and merits further study; this research may shed light on the pathogenesis of asthma.

A systematic review of predictive models for asthma development in children

Background

Asthma is the most common pediatric chronic disease affecting 9.6 % of American children. Delay in asthma diagnosis is prevalent, resulting in suboptimal asthma management. To help avoid delay in asthma diagnosis and advance asthma prevention research, researchers have proposed various models to predict asthma development in children. This paper reviews these models.

Methods

A systematic review was conducted through searching in PubMed, EMBASE, CINAHL, Scopus, the Cochrane Library, the ACM Digital Library, IEEE Xplore, and OpenGrey up to June 3, 2015. The literature on predictive models for asthma development in children was retrieved, with search results limited to human subjects and children (birth to 18 years). Two independent reviewers screened the literature, performed data extraction, and assessed article quality.

Results

The literature search returned 13,101 references in total. After manual review, 32 of these references were determined to be relevant and are discussed in the paper. We identify several limitations of existing predictive models for asthma development in children, and provide preliminary thoughts on how to address these limitations.

Conclusions

Existing predictive models for asthma development in children have inadequate accuracy. Efforts to improve these models’ performance are needed, but are limited by a lack of a gold standard for asthma development in children.

Electronic supplementary material

The online version of this article (doi:10.1186/s12911-015-0224-9) contains supplementary material, which is available to authorized users.

Cesarean section and disease associated with immune function

BACKGROUND

Earlier studies have shown that delivery by cesarean section (CS) is associated with an increased risk of disease associated with immune function in the offspring, but these studies have generally not discriminated between the effect of acute and elective CS.

OBJECTIVE

We sought to further explore these associations using discrimination between the effects of acute versus elective CS.

METHODS

We performed a population- and national register-based cohort study including all children born in Denmark from January 1997 through December 2012. Hazard ratios for diseases associated with immune function in children delivered by acute and elective CS with vaginal delivery as the reference were calculated by using Cox regression. All analyses were adjusted for gestational age, sex, birth weight, maternal age, maternal smoking during pregnancy, and complications during pregnancy (preeclampsia, eclampsia, hemorrhage, and hyperemesis).

RESULTS

A total of 750,569 children aged 0 to 14 years were included. Children delivered by both acute and elective CS had an increased risk of asthma, laryngitis, and gastroenteritis. Children delivered by acute CS had an increased risk of ulcerative colitis and celiac disease, whereas children delivered by elective CS had an increased risk of lower respiratory tract infection and juvenile idiopathic arthritis. The effect of elective CS was higher than the effect of acute CS on the risk of asthma.

CONCLUSION

Children delivered by CS are at increased risk of disease associated with immune function. The effect is mainly on diseases involving the mucosal immune system.

Infant respiratory infections and later respiratory hospitalisation in childhood

Acute respiratory infections (ARI) cause significant morbidity in infancy. We sought to quantify the relationship between ARI and development of respiratory morbidity in early childhood. Population-based longitudinal hospitalisation data were linked to perinatal, birth and death records for 145,580 Western Australian children from 1997 to 2002. We conducted Cox regression with sensitivity analyses to quantify the risk of recurrent ARI in infancy for respiratory hospitalisation after the age of 3 years. ARI in infancy was significantly related to respiratory hospitalisation before (hazard ratio (HR) 3.5, 95% CI 3.1-3.8) and after (HR 3.0, 95% CI 2.6-3.4) adjusting for known risk factors including maternal smoking during pregnancy, season of birth, delivery mode and gestational age. We noted a dose response with the number and length of infant ARI hospitalisations and increasing risk with no effect modification by gestational age. Results were similar when later respiratory hospitalisations were restricted to asthma hospitalisations only. Recurrent hospitalisations for ARI in infancy significantly increase the risk of respiratory morbidity and asthma requiring hospitalisation after the age of 3 years in a dose-response fashion. The increase in relative risk is not modified by gestational age. Efforts to reduce the occurrence of infant ARI are likely to have significant public health benefits.

Soy protein-based infant formulas with supplemental fructooligosaccharides: gastrointestinal tolerance and hydration status in newborn infants

Unlike milk-based infant formulas, soy-based infant formulas containing supplemental fructooligosaccharides (FOS) have not been clinically evaluated. A randomized, double-blind, 28 day parallel feeding trial compared gastrointestinal (GI) tolerance and hydration in healthy term newborn infants fed either a commercialized soy formula (with history of safe use) containing sucrose as 20% of total carbohydrate, no supplemental short-chain FOS (scFOS) and no mixed carotenoids (lutein, lycopene, beta-carotene) as a control (CF, n = 62 infants) or one of two experimental soy-based formulas, EF1 (n = 64) and EF2 (n = 62) containing scFOS (2.5 g/L) and mixed carotenoids. EF1 differed from EF2 by containing sucrose. Results indicated no significant study group differences (p > 0.05) in study completion rates (CF = 81, EF1 = 86, & EF2 = 87%), growth, mean rank stool consistency, stool frequency, formula intake, spit-up/vomit, and safety measures (urine specific gravity, USG; hydration status and adverse events). Mean USGs for study groups were normal (<1.03). The EF1 > CF group in percent yellow stools (p < 0.01 at age 14 days). In conclusion, the study suggested that term infants fed soy-based formulas supplemented with scFOS and mixed carotenoids, with or without sucrose in the 1st 35 days of infancy demonstrated good tolerance and hydration comparable to the control soy-based formula with history of safe use.

Caesarean section and hospitalization for respiratory syncytial virus infection: a population-based study

BACKGROUND AND OBJECTIVE

Hospitalization for respiratory syncytial virus (RSV) infection and asthma share common determinants, and meta-analyses indicate that children delivered by caesarean section (CS) are at increased risk of asthma. We aimed to investigate whether birth by CS is associated with an increased risk of hospitalization for RSV illness.

METHODS

This was a population-based national register-based cohort study, conducted between January, 1997 and June, 2003, which included all children born in Denmark and all hospitalizations for RSV disease in them from 0 to 23 months of age. We used Cox regression with adjustment for prematurity, asphyxia, birthweight, multiple births, single parenthood, maternal smoking during pregnancy, older siblings and asthma diagnoses up to 2 weeks before hospitalization for RSV infection, to compare the effects of acute or elective CS versus vaginal delivery, on subsequent hospitalization for RSV disease. A test for homogeneity was used to assess for effect over time.

RESULTS

399,175 children with 10,758 hospitalizations for RSV illness were included; 31,715 were born by acute CS and 30,965 by elective CS. Adjusted hazard ratios for hospitalization for RSV infection in children born by acute CS and by elective CS were 1.09 (1.01-1.17) and 1.27 (1.19-1.36), respectively. The effect of elective CS remained unchanged throughout the first 2 years of life (P = 0.53), whereas the effect of acute CS was only present in the second year of life (P = 0.001).

CONCLUSION

Delivery by caesarian section is associated with an increased risk of hospitalization for RSV infection. This effect continues at least throughout the first 2 years of life.

Elucidation of pathways driving asthma pathogenesis: development of a systems-level analytic strategy

Asthma is a genetically complex, chronic lung disease defined clinically as episodic airflow limitation and breathlessness that is at least partially reversible, either spontaneously or in response to therapy. Whereas asthma was rare in the late 1800s and early 1900s, the marked increase in its incidence and prevalence since the 1960s points to substantial gene × environment interactions occurring over a period of years, but these interactions are very poorly understood (1-6). It is widely believed that the majority of asthma begins during childhood and manifests first as intermittent wheeze. However, wheeze is also very common in infancy and only a subset of wheezy children progress to persistent asthma for reasons that are largely obscure. Here, we review the current literature regarding causal pathways leading to early asthma development and chronicity. Given the complex interactions of many risk factors over time eventually leading to apparently multiple asthma phenotypes, we suggest that deeply phenotyped cohort studies combined with sophisticated network models will be required to derive the next generation of biological and clinical insights in asthma pathogenesis.

A systematic review of predictive modeling for bronchiolitis

PURPOSE

Bronchiolitis is the most common cause of illness leading to hospitalization in young children. At present, many bronchiolitis management decisions are made subjectively, leading to significant practice variation among hospitals and physicians caring for children with bronchiolitis. To standardize care for bronchiolitis, researchers have proposed various models to predict the disease course to help determine a proper management plan. This paper reviews the existing state of the art of predictive modeling for bronchiolitis. Predictive modeling for respiratory syncytial virus (RSV) infection is covered whenever appropriate, as RSV accounts for about 70% of bronchiolitis cases.

METHODS

A systematic review was conducted through a PubMed search up to April 25, 2014. The literature on predictive modeling for bronchiolitis was retrieved using a comprehensive search query, which was developed through an iterative process. Search results were limited to human subjects, the English language, and children (birth to 18 years).

RESULTS

The literature search returned 2312 references in total. After manual review, 168 of these references were determined to be relevant and are discussed in this paper. We identify several limitations and open problems in predictive modeling for bronchiolitis, and provide some preliminary thoughts on how to address them, with the hope to stimulate future research in this domain.

CONCLUSIONS

Many problems remain open in predictive modeling for bronchiolitis. Future studies will need to address them to achieve optimal predictive models.

Morbidity due to acute lower respiratory infection in children with birth defects: a total population-based linked data study

BACKGROUND

Acute lower respiratory infections (ALRIs) are leading causes of hospitalisation in children. Birth defects occur in 5% of live births in Western Australia (WA). The association between birth defects and ALRI hospitalisation is unknown.

METHODS

We conducted a retrospective cohort study of 245,249 singleton births in WA (1996-2005). Population-based hospitalisation data were linked to the WA Register of Developmental Anomalies to investigate ALRI hospitalisations in children with and without birth defects. We used negative binomial regression to estimate associations between birth defects and number of ALRI hospitalisations before age 2 years, adjusting for known risk factors.

RESULTS

Overall, 9% of non-Aboriginal children and 37% of Aboriginal children with birth defects had at least one ALRI admission before age 2 years. Aboriginal children (IRR 2.3, 95% CI: 1.9-2.8) and non-Aboriginal children (IRR 2.0, 95% CI: 1.8-2.2) with birth defects had higher rates of hospitalisation for an ALRI than children with no birth defects. Rates of ALRI hospitalisation varied by type of defect but were increased for all major birth defects categories, the highest rate being for children with Down syndrome (IRR 8.0, 95% CI: 5.6-11.5). The rate of ALRI hospitalisation was 3 times greater in children with multiple birth defects than in those with isolated defects.

CONCLUSIONS

Children with birth defects experience higher rates of hospitalisation for ALRIs before age 2 years than children with no birth defects. Optimal vaccination coverage and immunoprophylaxis for specific categories of birth defects would assist in reducing hospitalisation rates for ALRI.

Epidemiological and genetic characteristics associated with the severity of acute viral bronchiolitis by respiratory syncytial virus

OBJECTIVE

to assess the epidemiological and genetic factors associated with severity of acute viral bronchiolitis (AVB) by respiratory syncytial virus (RSV).

DATA SOURCE

the key words "bronchiolitis", "risk factor", "genetics" and "respiratory syncytial virus", and all combinations among them were used to perform a search in the PubMed, SciELO, and Lilacs databases, of articles published after the year 2000 that included individuals younger than 2 years of age.

DATA SYNTHESIS

a total of 1,259 articles were found, and their respective summaries were read. Of these, 81 were selected, which assessed risk factors for the severity of AVB, and were read in full; the 60 most relevant studies were included. The epidemiologic factors associated with AVB severity by RSV were prematurity, passive smoking, young age, lack of breastfeeding, chronic lung disease, congenital heart disease, male gender, ethnicity, viral coinfection, low weight at admission, maternal smoking during pregnancy, atopic dermatitis, mechanical ventilation in the neonatal period, maternal history of atopy and/or asthma during pregnancy, season of birth, low socioeconomic status, Down syndrome, environmental pollution, living at an altitude > 2,500 meters above sea level, and cesarean section birth. Conversely, some children with severe AVB did not present any of these risk factors. In this regard, recent studies have verified the influence of genetic factors on the severity of AVB by RSV. Polymorphisms of the TLRs, RANTES, JUN, IFNA5, NOS2, CX3CR1, ILs, and VDR genes have been shown to be associated with more severe evolution of AVB by RSV.

CONCLUSION

the severity of AVB by RSV is a phenomenon that depends on the varying degrees of interaction among epidemiological, environmental, and genetic variables.

Role of public and private funding in the rising caesarean section rate: a cohort study

OBJECTIVE

The caesarean section rates have been rising in the developed world for over two decades. This study assessed the involvement of the public and private health sectors in this increase.

DESIGN

Population-based, retrospective cohort study.

SETTING

Public and private hospitals in Western Australia.

PARTICIPANTS

Included in this study were 155 646 births to nulliparous women during 1996-2008.

MAIN OUTCOME MEASURES

Caesarean section rates were calculated separately for four patient type groups defined according to mothers' funding source at the time of birth (public/private) and type of delivery hospital (public/private). The average annual per cent change (AAPC) for the caesarean section rates was calculated using joinpoint regression.

RESULTS

Overall, there were 45 903 caesarean sections performed (29%) during the study period, 24 803 in-labour and 21 100 prelabour. Until 2005, the rate of caesarean deliveries increased most rapidly on average annually for private patients delivering in private hospitals (AAPC=6.5%) compared with public patients in public hospitals (AAPC=4.3%, p<0.0001). This increase could mostly be attributed to an increase in prelabour caesarean deliveries for this group of women and could not be explained by an increase in breech deliveries, placenta praevia or multiple pregnancies.

CONCLUSIONS

Our results indicate that an increase in the prelabour caesarean delivery rate for private patients in private hospitals has been driving the increase in the caesarean section rate for nulliparous women since 1996. Future research with more detailed information on indication for the prelabour caesarean section is needed to understand the reasons for these findings.

Trends in the distribution of gestational age and contribution of planned births in New South Wales, Australia

BACKGROUND

There is concern that the rate of planned births (by pre-labour caesarean section or induction of labour) is increasing and that the gestation at which they are being conducted is decreasing. The aim of this study was to describe trends in the distribution of gestational age, and assess the contribution of planned birth to any such changes.

METHODS

We utilised the New South Wales (NSW) Perinatal Data Collection to undertake a population-based study of all births in NSW, Australia 1994-2009. Trends in gestational age were determined by year, labour onset and plurality of birth.

RESULTS

From 1994-2009, there was a gradual and steady left-shift in overall distribution of gestational age at birth, with a decline in the modal gestational age from 40 to 39 weeks. For singletons, there was a steady but significant reduction in the proportion of spontaneous births. Labour inductions increased in the proportion performed, with a gradual and changing shift in the distribution from a majority at 40 weeks to an increase at both 37-39 weeks and 41 weeks gestation. The proportion of pre-labour caesareans also increased steadily at each gestational age and doubled since 1994, with most performed at 39 weeks in 2009 compared with 38 weeks up to 2001.

CONCLUSIONS

Findings suggest a changing pattern towards births at earlier gestations, fewer births commencing spontaneously and increasing planned births. Factors associated with changing clinical practice and long-term implications on the health and well-being of mothers and babies should be assessed.

Can linked emergency department data help assess the out-of-hospital burden of acute lower respiratory infections? A population-based cohort study

Background

There is a lack of data on the out-of-hospital burden of acute lower respiratory infections (ALRI) in developed countries. Administrative datasets from emergency departments (ED) may assist in addressing this.

Methods

We undertook a retrospective population-based study of ED presentations for respiratory-related reasons linked to birth data from 245,249 singleton live births in Western Australia. ED presentation rates <9 years of age were calculated for different diagnoses and predictors of ED presentation <5 years were assessed by multiple logistic regression.

Results

ED data from metropolitan WA, representing 178,810 births were available for analysis. From 35,136 presentations, 18,582 (52.9%) had an International Classification of Diseases (ICD) code for ALRI and 434 had a symptom code directly relating to an ALRI ICD code. A further 9600 presentations had a non-specific diagnosis. From the combined 19,016 ALRI presentations, the highest rates were in non-Aboriginal children aged 6–11 months (81.1/1000 child-years) and Aboriginal children aged 1–5 months (314.8/1000). Croup and bronchiolitis accounted for the majority of ALRI ED presentations. Of Aboriginal births, 14.2% presented at least once to ED before age 5 years compared to 6.5% of non-Aboriginal births. Male sex and maternal age <20 years for Aboriginal children and 20–29 years for non-Aboriginal children were the strongest predictors of presentation to ED with ALRI.

Conclusions

ED data can give an insight into the out-of-hospital burden of ALRI. Presentation rates to ED for ALRI were high, but are minimum estimates due to current limitations of the ED datasets. Recommendations for improvement of these data are provided. Despite these limitations, ALRI, in particular bronchiolitis and croup are important causes of presentation to paediatric EDs.

Increase in caesarean deliveries after the Australian Private Health Insurance Incentive policy reforms

BACKGROUND

The Australian Private Health Insurance Incentive (PHII) policy reforms implemented in 1997-2000 increased PHI membership in Australia by 50%. Given the higher rate of obstetric interventions in privately insured patients, the reforms may have led to an increase in surgical deliveries and deliveries with longer hospital stays. We aimed to investigate the effect of the PHII policy introduction on birth characteristics in Western Australia (WA).

METHODS AND FINDINGS

All 230,276 birth admissions from January 1995 to March 2004 were identified from administrative birth and hospital data-systems held by the WA Department of Health. Average quarterly birth rates after the PHII introduction were estimated and compared with expected rates had the reforms not occurred. Rate and percentage differences (including 95% confidence intervals) were estimated separately for public and private patients, by mode of delivery, and by length of stay in hospital following birth. The PHII policy introduction was associated with a 20% (-21.4 to -19.3) decrease in public birth rates, a 51% (45.1 to 56.4) increase in private birth rates, a 5% (-5.3 to -5.1) and 8% (-8.9 to -7.9) decrease in unassisted and assisted vaginal deliveries respectively, a 5% (-5.3 to -5.1) increase in caesarean sections with labour and 10% (8.0 to 11.7) increase in caesarean sections without labour. Similarly, birth rates where the infant stayed 0-3 days in hospital following birth decreased by 20% (-21.5 to -18.5), but rates of births with >3 days in hospital increased by 15% (12.2 to 17.1).

CONCLUSIONS

Following the PHII policy implementation in Australia, births in privately insured patients, caesarean deliveries and births with longer infant hospital stays increased. The reforms may not have been beneficial for quality obstetric care in Australia or the burden of Australian hospitals.