Incidence, Intrapartum Risk Factors, and Prognosis of Neonatal Hypoxic-Ischemic Encephalopathy Among Infants Born at 35 Weeks Gestation or More.

INTRODUCTION: Neonatal hypoxic-ischemic encephalopathy (HIE) is associated with neonatal mortality, acute neurological injury, and long-term neurodevelopmental disabilities; however, the association between intrapartum factors and HIE remains unclear. METHODS: This population-based cohort study used linked obstetrical and newborn data derived from the Nova Scotia Atlee Perinatal Database (NSAPD, 1988-2015) and the AC Allen Perinatal Follow-Up Program Database (2006-2015) for all pregnancies with live, non-anomalous newborns ≥35 weeks gestation, not delivered by pre-labour cesarean section. Temporal trends in HIE incidence were described, and logistic regression estimated odds ratios (OR) with 95% confidence intervals (CI) for the association of intrapartum factors with HIE. RESULTS: The NSAPD identified 227 HIE cases in the population of 226 711 deliveries from 1988 to 2015. Women with clinical chorioamnionitis in labour (OR 8.0; 95% CI 3.9-16), emergency cesarean delivery (OR 10; 95% CI 7.6-14), shoulder dystocia (OR 3.5; 95% CI 2.1-5.7), placental abruption (OR 18; 95% CI 11-29), and cord prolapse (OR 30; 95% CI 15-61) were more likely to have newborns with HIE. Two-thirds of newborns with HIE had an abnormal intrapartum fetal heart rate tracing. The mortality rate among infants with HIE was 27% by 3 years of age. Neurodevelopmental outcomes in the surviving infants were normal in 43% and showed severe developmental delay in 40%. CONCLUSION: Overall, the rate of HIE was low in infants born at ≥35 weeks gestation. The identification of associated intrapartum factors should promote increased surveillance in these clinical situations and emphasize the importance of careful management to optimize newborn outcomes.

Comparison of logistic regression with machine learning methods for the prediction of fetal growth abnormalities: a retrospective cohort study.

BACKGROUND: While there is increasing interest in identifying pregnancies at risk for adverse outcome, existing prediction models have not adequately assessed population-based risks, and have been based on conventional regression methods. The objective of the current study was to identify predictors of fetal growth abnormalities using logistic regression and machine learning methods, and compare diagnostic properties in a population-based sample of infants. METHODS: Data for 30,705 singleton infants born between 2009 and 2014 to mothers resident in Nova Scotia, Canada was obtained from the Nova Scotia Atlee Perinatal Database. Primary outcomes were small (SGA) and large for gestational age (LGA). Maternal characteristics pre-pregnancy and at 26 weeks were studied as predictors. Logistic regression and select machine learning methods were used to build the models, stratified by parity. Area under the curve was used to compare the models; relative importance of predictors was compared qualitatively. RESULTS: 7.9% and 13.5% of infants were SGA and LGA, respectively; 48.6% of births were to primiparous women and 51.4% were to multiparous women. Prediction of SGA and LGA was poor to fair (area under the curve 60-75%) and improved with increasing parity and pregnancy information. Smoking, previous low birthweight infant, and gestational weight gain were important predictors for SGA; pre-pregnancy body mass index, gestational weight gain, and previous macrosomic infant were the strongest predictors for LGA. CONCLUSIONS: The machine learning methods used in this study did not offer any advantage over logistic regression in the prediction of fetal growth abnormalities. Prediction accuracy for SGA and LGA based on maternal information is poor for primiparous women and fair for multiparous women.

Type of Labour in the First Pregnancy and Cumulative Perinatal Morbidity.

OBJECTIVE: To estimate cumulative perinatal morbidity among infants delivered at term, according to the type of labour in the first pregnancy, when the first pregnancy was low risk. METHODS: In a 26-year population-based cohort study (1988-2013) using the Nova Scotia Atlee Perinatal Database, we identified the type of labour in successive pregnancies in low-risk, nulliparous women at term in their first pregnancy (who had at least one subsequent pregnancy), and also identified perinatal outcomes in subsequent deliveries according to the type of labour in the first pregnancy. RESULTS: A total of 37 756 pregnancies satisfied inclusion and exclusion criteria; of these, 1382 (3.7%) had a Caesarean section without labour in the first pregnancy. Rates of most adverse perinatal outcomes were low (≤ 1%). The risks for stillbirth were low in subsequent deliveries, including those that followed CS without labour in the first pregnancy, and the risks for the overall severe perinatal morbidity outcome were less than 10% for all subsequent deliveries. CONCLUSION: The absolute risks for severe perinatal morbidity outcomes in a population of low-risk women (with up to four additional pregnancies) were small, regardless of type of labour in the first pregnancy. This finding provides important information on perinatal outcomes in subsequent pregnancies when considering type of labour in the first pregnancy.

Twin Birth Study: 2-year neurodevelopmental follow-up of the randomized trial of planned cesarean or planned vaginal delivery for twin pregnancy.

BACKGROUND: The Twin Birth Study randomized women with uncomplicated pregnancies, between 32(0/7)-38(6/7) weeks' gestation where the first twin was in cephalic presentation, to a policy of either a planned cesarean or planned vaginal delivery. The primary analysis showed that planned cesarean delivery did not increase or decrease the risk of fetal/neonatal death or serious neonatal morbidity as compared with planned vaginal delivery. OBJECTIVE: This study presents the secondary outcome of death or neurodevelopmental delay at 2 years of age. STUDY DESIGN: A total of 4603 children from the initial cohort of 5565 fetuses/infants (83%) contributed to the outcome of death or neurodevelopmental delay. Surviving children were screened using the Ages and Stages Questionnaire with abnormal scores validated by a clinical neurodevelopmental assessment. The effect of planned cesarean vs planned vaginal delivery on death or neurodevelopmental delay was quantified using a logistic model to control for stratification variables and using generalized estimating equations to account for the nonindependence of twin births. RESULTS: Baseline maternal, pregnancy, and infant characteristics were similar. Mean age at assessment was 26 months. There was no significant difference in the outcome of death or neurodevelopmental delay: 5.99% in the planned cesarean vs 5.83% in the planned vaginal delivery group (odds ratio, 1.04; 95% confidence interval, 0.77-1.41; P = .79). CONCLUSION: A policy of planned cesarean delivery provides no benefit to children at 2 years of age compared with a policy of planned vaginal delivery in uncomplicated twin pregnancies between 32(0/7)-38(6/7)weeks' gestation where the first twin is in cephalic presentation.

An Algorithm for Predicting Neonatal Mortality in Threatened Very Preterm Birth.

OBJECTIVE: To develop a prediction model for neonatal mortality using information readily available in the antenatal period. METHODS: A multiple logistic regression model of a complete population-based geographically defined cohort of very preterm infants of 23+0 to 30+6 weeks' gestation was used to identify antenatal factors which were predictive of mortality in this population. Infants lt; 23 weeks and those with major anomalies were excluded. RESULTS: Between 1996 and 2012, 1240 live born infants lt; 31 weeks' gestation were born to women residing in Nova Scotia. Decreasing gestational age strongly predicted an increased mortality rate. Other factors significantly contributing to increased mortality included classification as small for gestational age, oligohydramnios, maternal psychiatric disorders, antenatal antibiotic therapy, and monochorionic twins. Reduced neonatal mortality was associated with antenatal use of antihypertensive agents and use of corticosteroids of any duration of therapy given at least 24 hours before delivery. An algorithm was developed to estimate the risk of mortality without the need for a calculator. CONCLUSION: Prediction of the probability of neonatal mortality is influenced by maternal and fetal factors. An algorithm to estimate the risk of mortality facilitates counselling and informs shared decision making regarding obstetric management.

Objectif : Élaborer un modèle prédictif en ce qui concerne la mortalité néonatale au moyen de renseignements faciles à obtenir au cours de la période prénatale. Méthodes : Nous avons eu recours au modèle de régression logistique multiple d'une cohorte exhaustive, populationnelle et définie géographiquement de nouveau-nés très prématurés (âge gestationnel : de 23+0 à 30+6 semaines) pour identifier les facteurs prénataux permettant de prédire la mortalité au sein de cette population. Les nouveau-nés dont l'âge gestationnel était inférieur à 23 semaines et ceux qui présentaient des anomalies majeures ont été exclus. Résultats : Entre 1996 et 2012, 1 240 enfants nés vivants à moins de 31 semaines de gestation ont été issus de femmes résidant en Nouvelle-Écosse. La baisse de l'âge gestationnel constituait un facteur solide permettant de prédire une hausse du taux de mortalité. Parmi les autres facteurs contribuant de façon significative à la hausse du taux de mortalité, on trouvait l'hypotrophie fœtale, l'oligohydramnios, les troubles psychiatriques maternels, l'antibiothérapie prénatale et les jumeaux monozygotes. La baisse du taux de mortalité néonatale était associée à l'utilisation prénatale d'antihypertenseurs et à l'utilisation de corticostéroïdes (peu importe la durée du traitement) administrés au moins 24 heures avant l'accouchement. Nous avons élaboré un algorithme pour estimer le risque de mortalité sans avoir recours à une calculatrice. Conclusion : La prévision de la probabilité de la mortalité néonatale est influencée par des facteurs maternels et fœtaux. Le fait de disposer d'un algorithme pour estimer le risque de mortalité facilite le counseling et éclaire le processus décisionnel partagé en ce qui concerne la prise en charge obstétricale.

Post-resuscitation care for neonates receiving positive pressure ventilation at birth.

OBJECTIVES: To investigate if postresuscitation care (PRC) is indicated for all infants ≥35 weeks' gestation who receive positive pressure ventilation (PPV) at birth, explore the aspects of this care and the factors most predictive of it. METHODS: Our hospital admits any infant who requires PPV at birth to special (intermediate/intensive) neonatal care unit (SNCU) for observation for at least 6 hours. All infants ≥35 weeks' gestation born between 1994 and 2013, who received PPV at birth, were reviewed. We examined perinatal factors that could predict the need for PRC after short (<1 minute) and prolonged (≥1 minute) PPV, admission course, neonatal morbidities, and the aspects of care given. RESULTS: Among 87 464 infants born, 3658 (4.2%) had PPV at birth with 3305 (90%) admitted for PRC. Of those, 1558 (42.6%) were in the short PPV group and 2100 (57.4%) in the prolonged PPV group. Approximately 59% of infants who received short PPV stayed in the SNCU for ≥1 day. Infants who received prolonged PPV were more likely to have morbidities and require special neonatal care. Multiple logistic regression analysis revealed the risk factors of placental abruption, assisted delivery, small-for-dates, gestational age <37 weeks, low 5-minute Apgar score, and need for intubation at birth to be independent predictors for SNCU stay ≥1 day and need for assisted ventilation, central lines, and parenteral nutrition. CONCLUSIONS: Our data support the need for PRC even for infants receiving short PPV at birth.

Trends in the prevalence of cerebral palsy among very preterm infants (<31 weeks' gestational age).

BACKGROUND: The birth prevalence of cerebral palsy varies over time among very preterm infants, and the reasons are poorly understood. OBJECTIVE: To describe the variation in the prevalence of cerebral palsy among very preterm infants over time, and to relate these differences to other maternal or neonatal factors. METHODS: A population-based cohort of very preterm infants was evaluated over a 20-year period (1988 to 2007) divided into four equal epochs. RESULTS: The prevalence of cerebral palsy peaked in the third epoch (1998 to 2002) while mortality rate peaked in the second epoch (1993 to 1997). Maternal anemia, tocolytic use and neonatal need for home oxygen were highest in the third epoch. CONCLUSIONS: Lower mortality rates did not correlate well with the prevalence of cerebral palsy. Maternal risk factors, anemia and tocolytic use, and the newborn need for home oxygen were highest during the same epoch as the peak prevalence of cerebral palsy.

HISTORIQUE: La prévalence de paralysie cérébrale à la naissance varie au fil du temps chez les nourrissons très prématurés, et on en comprend mal les raisons. OBJECTIF: Décrire la variation de la prévalence de paralysie cérébrale chez les nourrissons très prématurés au fil du temps et les relier à d'autres facteurs relatifs à la mère ou à la période néonatale. MÉTHODOLOGIE: Les chercheurs ont évalué une cohorte de nourrissons très prématurés sur 20 ans (1988 à 2007), divisée en quatre périodes d'égale longueur. RÉSULTATS: La prévalence de paralysie cérébrale a atteint un pic pendant la troisième période (1998 à 2002), tandis que le pic du taux de mortalité est survenu pendant la deuxième période (1993 à 1997). L'anémie et l'utilisation de tocolytiques chez la mère, ainsi que l'assistance ventilatoire néonatale à domicile, étaient plus élevées pendant la troisième période. CONCLUSIONS: Les taux de mortalité plus faibles n'étaient pas bien corrélés avec la prévalence de paralysie cérébrale. Les facteurs de risque de la mère, c'est-à-dire l'anémie et l' utilisation de tocolytiques, de même que l'assistance ventilatoire du nouveau-né à domicile, étaient tous plus élevés pendant la période qui s'associait à la plus forte prévalence de paralysie cérébrale.

Effects of socioeconomic position and clinical risk factors on spontaneous and iatrogenic preterm birth.

BACKGROUND: The literature shows a variable and inconsistent relationship between socioeconomic position and preterm birth. We examined risk factors for spontaneous and iatrogenic preterm birth, with a focus on socioeconomic position and clinical risk factors, in order to explain the observed inconsistency. METHODS: We carried out a retrospective population-based cohort study of all singleton deliveries in Nova Scotia from 1988 to 2003. Data were obtained from the Nova Scotia Atlee Perinatal Database and the federal income tax T1 Family Files. Separate logistic models were used to quantify the association between socioeconomic position, clinical risk factors and spontaneous preterm birth and iatrogenic preterm birth. RESULTS: The study population included 132,714 singleton deliveries and the rate of preterm birth was 5.5%. Preterm birth rates were significantly higher among the women in the lowest (versus the highest) family income group for spontaneous (rate ratio 1.14, 95% confidence interval (CI) 1.03, 1.25) but not iatrogenic preterm birth (rate ratio 0.95, 95% CI 0.75, 1.19). Adjustment for maternal characteristics attenuated the family income-spontaneous preterm birth relationship but strengthened the relationship with iatrogenic preterm birth. Clinical risk factors such as hypertension were differentially associated with spontaneous (rate ratio 3.92, 95% CI 3.47, 4.44) and iatrogenic preterm (rate ratio 14.1, 95% CI 11.4, 17.4) but factors such as diabetes mellitus were not (rate ratio 4.38, 95% CI 3.21, 5.99 for spontaneous and 4.02, 95% CI 2.07, 7.80 for iatrogenic preterm birth). CONCLUSIONS: Socioeconomic position and clinical risk factors have different effects on spontaneous and iatrogenic preterm. Recent temporal increases in iatrogenic preterm birth appear to be responsible for the inconsistent relationship between socioeconomic position and preterm birth.

A population-based case-control study of drinking-water nitrate and congenital anomalies using Geographic Information Systems (GIS) to develop individual-level exposure estimates.

Animal studies and epidemiological evidence suggest an association between prenatal exposure to drinking water with elevated nitrate (NO3-N) concentrations and incidence of congenital anomalies. This study used Geographic Information Systems (GIS) to derive individual-level prenatal drinking-water nitrate exposure estimates from measured nitrate concentrations from 140 temporally monitored private wells and 6 municipal water supplies. Cases of major congenital anomalies in Kings County, Nova Scotia, Canada, between 1988 and 2006 were selected from province-wide population-based perinatal surveillance databases and matched to controls from the same databases. Unconditional multivariable logistic regression was performed to test for an association between drinking-water nitrate exposure and congenital anomalies after adjusting for clinically relevant risk factors. Employing all nitrate data there was a trend toward increased risk of congenital anomalies for increased nitrate exposure levels though this was not statistically significant. After stratification of the data by conception before or after folic acid supplementation, an increased risk of congenital anomalies for nitrate exposure of 1.5-5.56 mg/L (2.44; 1.05-5.66) and a trend toward increased risk for >5.56 mg/L (2.25; 0.92-5.52) was found. Though the study is likely underpowered, these results suggest that drinking-water nitrate exposure may contribute to increased risk of congenital anomalies at levels below the current Canadian maximum allowable concentration.

A randomized trial of planned cesarean or vaginal delivery for twin pregnancy.

BACKGROUND: Twin birth is associated with a higher risk of adverse perinatal outcomes than singleton birth. It is unclear whether planned cesarean section results in a lower risk of adverse outcomes than planned vaginal delivery in twin pregnancy. METHODS: We randomly assigned women between 32 weeks 0 days and 38 weeks 6 days of gestation with twin pregnancy and with the first twin in the cephalic presentation to planned cesarean section or planned vaginal delivery with cesarean only if indicated. Elective delivery was planned between 37 weeks 5 days and 38 weeks 6 days of gestation. The primary outcome was a composite of fetal or neonatal death or serious neonatal morbidity, with the fetus or infant as the unit of analysis for the statistical comparison. RESULTS: A total of 1398 women (2795 fetuses) were randomly assigned to planned cesarean delivery and 1406 women (2812 fetuses) to planned vaginal delivery. The rate of cesarean delivery was 90.7% in the planned-cesarean-delivery group and 43.8% in the planned-vaginal-delivery group. Women in the planned-cesarean-delivery group delivered earlier than did those in the planned-vaginal-delivery group (mean number of days from randomization to delivery, 12.4 vs. 13.3; P=0.04). There was no significant difference in the composite primary outcome between the planned-cesarean-delivery group and the planned-vaginal-delivery group (2.2% and 1.9%, respectively; odds ratio with planned cesarean delivery, 1.16; 95% confidence interval, 0.77 to 1.74; P=0.49). CONCLUSIONS: In twin pregnancy between 32 weeks 0 days and 38 weeks 6 days of gestation, with the first twin in the cephalic presentation, planned cesarean delivery did not significantly decrease or increase the risk of fetal or neonatal death or serious neonatal morbidity, as compared with planned vaginal delivery. (Funded by the Canadian Institutes of Health Research; ClinicalTrials.gov number, NCT00187369; Current Controlled Trials number, ISRCTN74420086.).

The association between caesarean section and childhood obesity revisited: a cohort study.

BACKGROUND: The mode of delivery has recently gained attention as another potential perinatal risk factor for childhood obesity but results are conflicting. OBJECTIVE: To examine whether caesarean section is independently associated with childhood obesity after adjusting for a broad range of confounding factors. METHODS: The current study used a population-based survey in Grade 5 students linked to a provincial perinatal registry in the Canadian province of Nova Scotia. Associations between caesarean section and childhood overweight and obesity at age 10/11 years were examined using multiple logistic regression. RESULTS: Of the 4298 students who participated in the 2003 Children's Lifestyle and School Performance Study (response rate 51.1%), 3426 (80%) could be linked with information in the Atlee Perinatal Database, and 2988 mother-child pairs (70%) had complete information on the exposure and outcome. Compared to vaginal delivery, caesarean section was associated with offspring obesity (OR) 1.49, 95% CI 1.10 to 2.00) in the univariate analysis. After adding maternal prepregnancy weight to the multiple regression model, the OR for obesity dropped from 1.48 to 1.20 (95% CI 0.87 to 1.65). When caesarean section with and without labour were considered separately, we found no statistically significant associations relative to the vaginal delivery group (OR 1.24, 95% CI 0.84 to 1.82 and OR 1.03, 95% CI 0.58 to 1.84). CONCLUSION: Our results do not support a causal association between caesarean section and childhood obesity. Maternal prepregnancy weight was an important confounder in the association between caesarean delivery and childhood obesity and needs to be considered in future studies.

Treatment of patent ductus arteriosus and neonatal mortality/morbidities: adjustment for treatment selection bias.

OBJECTIVE: To examine the association between treatment for patent ductus arteriosus (PDA) and neonatal outcomes in preterm infants, after adjustment for treatment selection bias. STUDY DESIGN: Secondary analyses were conducted using data collected by the Canadian Neonatal Network for neonates born at a gestational age ≤ 32 weeks and admitted to neonatal intensive care units in Canada between 2004 and 2008. Infants who had PDA and survived beyond 72 hours were included in multivariable logistic regression analyses that compared mortality or any severe neonatal morbidity (intraventricular hemorrhage grades ≥ 3, retinopathy of prematurity stages ≥ 3, bronchopulmonary dysplasia, or necrotizing enterocolitis stages ≥ 2) between treatment groups (conservative management, indomethacin only, surgical ligation only, or both indomethacin and ligation). Propensity scores (PS) were estimated for each pair of treatment comparisons, and used in PS-adjusted and PS-matched analyses. RESULTS: Among 3556 eligible infants with a diagnosis of PDA, 577 (16%) were conservatively managed, 2026 (57%) received indomethacin only, 327 (9%) underwent ligation only, and 626 (18%) were treated with both indomethacin and ligation. All multivariable and PS-based analyses detected significantly higher mortality/morbidities for surgically ligated infants, irrespective of prior indomethacin treatment (OR ranged from 1.25-2.35) compared with infants managed conservatively or those who received only indomethacin. No significant differences were detected between infants treated with only indomethacin and those managed conservatively. CONCLUSIONS: Surgical ligation of PDA in preterm neonates was associated with increased neonatal mortality/morbidity in all analyses adjusted for measured confounders that attempt to account for treatment selection bias.

The role of maternal smoking in effect of fetal growth restriction on poor scholastic achievement in elementary school.

Fetal growth restriction and maternal smoking during pregnancy are independently implicated in lowering intellectual attainment in children. We hypothesized that only reduction of fetal growth that is attributable to extrinsic causes (e.g., maternal smoking) affects intellectual development of a child. Cross-sectional survey of 3,739 students in Nova Scotia (Canada) in 2003 was linked with the perinatal database, parental interviews on socio-demographic factors and the performance on standardized tests when primarily 11-12 years of age, thereby forming a retrospective cohort. Data was analyzed using hierarchical logistic regression with correction for clustering of children within schools. The risk of poor test result among children born small-for-gestational-age (SGA) to mothers who smoked was 29.4%, higher than in any other strata of maternal smoking and fetal growth. The adjusted odds ratio among SGA children born to mothers who smoked was the only one elevated compared to children who were not growth restricted and born to mothers who did not smoke (17.0%, OR = 1.46, 95% CI 1.02, 2.09). Other perinatal, maternal and socio-demographic factors did not alter this pattern of effect modification. Heterogeneity of etiology of fetal growth restriction should be consider in studies that address examine its impact on health over life course.

The influence of changing post-term induction of labour patterns on severe neonatal morbidity.

OBJECTIVE: To estimate the influence of changing practice patterns of post-term induction of labour on severe neonatal morbidity. METHODS: This population-based cohort study used data from the Nova Scotia Atlee Perinatal Database to evaluate the effect of post-term induction of labour on stillbirth and neonatal mortality and severe neonatal morbidity in low-risk pregnancies. The study population included all pregnant women ≥ 40 weeks' gestation delivering in Nova Scotia from 1988 to 2008 who underwent induction of labour with a single fetus in cephalic presentation. Major congenital anomalies and pre-existing or severe gestational hypertension and diabetes were excluded. Women delivering post-term from 1994 to 2008 (after the Post-term Pregnancy Trial) were compared with women delivering from 1988 to 1992 to evaluate outcomes with changing maternal characteristics and obstetric practice patterns. RESULTS: Evaluation and comparison of time epochs (1988 to 1992, 1994 to 1998, 1999 to 2003, and 2004 to 2008) demonstrated an increased risk for perinatal mortality or severe neonatal morbidity, especially low five-minute Apgar score, among both nulliparous and multiparous women. There were no significant differences in the risks for stillbirth or perinatal mortality over time. Comparable relationships were demonstrated in a subgroup of lower risk women. CONCLUSION: The increase in post-term induction of labour with time is associated with a significant increase in severe neonatal morbidity, especially among infants born to multiparous women. Evaluation of the antepartum and intrapartum management of these low-risk pregnancies may provide additional information to reduce morbidity.

Influence of definition based versus pragmatic birth registration on international comparisons of perinatal and infant mortality: population based retrospective study.

OBJECTIVES: To examine variations in the registration of extremely low birthweight and early gestation births and to assess their effect on perinatal and infant mortality rankings of industrialised countries. DESIGN: Retrospective population based study. SETTING: Australia, Canada, European countries, and the United States for 2004; Australia, Canada, and New Zealand for 2007. POPULATION: National data on live births and on fetal, neonatal, and infant deaths. MAIN OUTCOME MEASURES: Reported proportions of live births with birth weight/gestational age of less than 500 g, less than 1000 g, less than 24 weeks, and less than 28 weeks; crude rates of fetal, neonatal, and infant mortality; mortality rates calculated after exclusion of births under 500 g, under 1000 g, less than 24 weeks, and less than 28 weeks. RESULTS: The proportion of live births under 500 g varied widely from less than 1 per 10,000 live births in Belgium and Ireland to 10.8 per 10,000 live births in Canada and 16.9 in the United States. Neonatal deaths under 500 g, as a proportion of all neonatal deaths, also ranged from less than 1% in countries such as Luxembourg and Malta to 29.6% in Canada and 31.1% in the United States. Rankings of countries based on crude fetal, neonatal, and infant mortality rates differed substantially from rankings based on rates calculated after exclusion of births with a birth weight of less than 1000 g or a gestational age of less than 28 weeks. CONCLUSIONS: International differences in reported rates of extremely low birthweight and very early gestation births probably reflect variations in registration of births and compromise the validity of international rankings of perinatal and infant mortality.

Use and cost of health services among overweight and obese Canadian children.

BACKGROUND: Along with a dramatic rise in the rates of childhood obesity, obesity-related disorders, such as type 2 diabetes, hypertension, and obstructive sleep apnea, are seen with increasing frequency in children. As a consequence, overweight and obese children may use health care services more often than their normal weight peers. The aim of the current study was to assess health service use and costs across categories of weight status. METHODS: Prospective cohort study using data from a population-based survey among grade 5 children in the Canadian province of Nova Scotia linked with administrative health data, using a combination of deterministic and probabalistic matching (n = 4 380). Total health care costs (physician and hospital costs), lifetime (up to age 14 years) physician costs and number of physician visits were assessed in a series of multiple regression models. RESULTS: There was a gradient for higher costs and utilization across the three weight groups. Total health care costs in the three years following the survey were 21% (95% CI: 2-43) higher in obese children compared with normal weight children. Obese children also had significantly higher lifetime physician costs and more physician visits than their normal weight peers. The health care cost trajectories of normal weight and obese children drift apart as early as 3 years of age. Interpretation. Obese children in the Canadian province of Nova Scotia have significantly higher health care costs and more physician visits and specialist referrals than their normal weight peers, highlighting the need for cost-effectiveness studies of obesity prevention programs.

The role of prenatal, obstetric and neonatal factors in the development of autism.

We conducted a linked database cohort study of infants born between 1990 and 2002 in Nova Scotia, Canada. Diagnoses of autism were identified from administrative databases with relevant diagnostic information to 2005. A factor representing genetic susceptibility was defined as having an affected sibling or a mother with a history of a psychiatric or neurologic condition. Among 129,733 children, there were 924 children with an autism diagnosis. The results suggest that among those with low genetic susceptibility, some maternal and obstetric factors may have an independent role in autism etiology whereas among genetically susceptible children, these factors appear to play a lesser role. The role of pre-pregnancy obesity and excessive weight gain during pregnancy on autism risk require further investigation.

Early opioid infusion and neonatal outcomes in preterm neonates ≤28 weeks' gestation.

We sought to assess risk-adjusted neonatal outcomes of extremely preterm infants who received opioid infusion during early postnatal period. A retrospective analysis of preterm infants ≤28 weeks' gestational age (GA) admitted to neonatal intensive care units in the Canadian Neonatal Network was conducted comparing infants on the basis of receipt of opioid infusion during day 1 and day 3 after birth. Rates of mortality, severe neurological injury, severe retinopathy of prematurity, and chronic lung disease were compared. A total 362 infants received opioid infusion on day 1 and day 3, whereas 4419 infants did not receive opioid infusion. Baseline comparison revealed higher number of males, infants of GA <26 weeks, low Apgar score, and higher Score for Neonatal Acute Physiology scores among those who received opioid infusion. Neonates who received opioid infusion had higher risk for mortality (adjusted odds ratio [AOR] 1.57, 95% confidence interval [CI] 1.13, 2.18), severe neurological injury (AOR 1.63, 95% CI 1.30, 2.04), severe retinopathy of prematurity (AOR 1. 39, 95% CI 1.08, 1.79), and bronchopulmonary dysplasia (AOR 1.36, 95% CI 1.03, 1.79). Early exposure to opioid infusion in the first 3 days was associated with higher risk of adverse outcomes in extremely preterm infants.

Temporal trends and regional variations in severe maternal morbidity in Canada, 2003 to 2007.

OBJECTIVE: To identify temporal trends and regional variations in severe maternal morbidity in Canada using routine hospitalization data. METHODS: We used a previously identified set of International Statistical Classification of Diseases and Related Health Problems, 10th Revision (ICD-10CA) and Canadian Classification of Interventions (CCI) codes to estimate rates of severe maternal morbidity in Canada (excluding Quebec) for 2003 to 2007 using the Discharge Abstract Database of the Canadian Institute for Health Information (CIHI). Rates and 95% confidence intervals were calculated by year and within each province and territory and contrasted using the chi-square or Fisher exact test. RESULTS: The overall rate of severe maternal morbidity was 13.8 per 1000 deliveries (95% CI 13.6 to 14.0). Five provinces or territories had rates that were significantly higher than those in the rest of the country: Newfoundland and Labrador (19.0 per 1000; 95% CI 17.2 to 20.8), Saskatchewan (16.9 per 1000; 95% CI 15.9 to 18.0), Alberta (15.4 per 1000; 95% CI 14.9 to 15.9), Northwest Territories (22.5 per 1000; 95% CI 18.0 to 27.7), and Nunavut (20.2 per 1000; 95% CI 14.2 to 27.8). Rates of some illnesses declined (e.g., eclampsia rates decreased from 12.4 in 2003 to 5.7 per 10 000 deliveries in 2007, P<0.001), while others increased (e.g., postpartum hemorrhage with blood transfusion rates increased from 36.6 in 2003 to 44.3 per 10 000 deliveries in 2007, P<0.001). Interprovincial/territorial contrasts showed several disparities with respect to specific maternal illnesses. CONCLUSION: The observed temporal trends and regional disparities in severe maternal morbidity may represent important population health phenomena, and further investigation is required to assess their importance.