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Children and youth with medical complexity are a diverse group with uncommon diagnoses, a spectrum of needs and varying access to supports. Although this population represents a small proportion of all children, their unique needs lead to substantial use of healthcare services. With its first pan-Canadian report on children and youth with medical complexity, the Canadian Institute for Health Information examined how this population uses healthcare services. Key findings include the wide variation in the rate of medical complexity among children and youth across Canada. Children and youth with medical complexity were found to require a high proportion of hospital and emergency department care; however, their readmission rates were found to be lower than that of the general pediatric population.

Federal, provincial and territorial governments endorsed agreements in August of 2017 to focus on the shared health priorities of home, community, mental health and addictions care (Government of Canada 2017). The related $11 billion federal investment over a 10-year period aims to improve access for Canadians to effective and appropriate services in these areas (Government of Canada 2019).

Table S3. Preoperative cardiac testing methodology summary. Tables describing methodological details and relevant codes used for preoperative cardiac testing study. (DOCX 17 kb)

Table S4. Screening mammography methodology summary. Tables describing methodological details and data handling procedure for screening mammography study. (DOCX 15 kb)

Table S1. Utilization of unnecessary services related to three Choosing Wisely Canada (CWC) recommendations. Table describing CWC recommendations for lower back pain imaging, preoperative cardiac testing, and screening mammography, and methodological details pertaining to each of the three studies. (DOCX 16 kb)

Background Through the Choosing Wisely Canada (CWC) campaign, national medical specialty societies have released hundreds of recommendations against health care services that are unnecessary, i.e. present little to no benefit or cause avoidable harm. Despite growing interest in unnecessary care both within Canada and internationally, prior research has typically avoided taking a national or even multi-jurisdictional approach in measuring the extent of the issue. This study estimates use of three unnecessary services identified by CWC recommendations across multiple Canadian jurisdictions. Methods Two retrospective cohort studies were conducted using administrative health care data collected between fiscal years 2011/12 and 2012/13 to respectively quantify use of 1) diagnostic imaging (spinal X-ray, CT or MRI) among Albertan patients following a visit for lower back pain and 2) cardiac tests (electrocardiogram, chest X-ray, stress test, or transthoracic echocardiogram) prior to low-risk surgical procedures in Alberta, Saskatchewan, and Ontario. A cross-sectional study of the 2012 Canadian Community Health Survey was also conducted to estimate 3) the proportion of females aged 40–49 that reported having a routine mammogram in the past two years. Results Use of unnecessary care was relatively frequent across all three services and jurisdiction measured: 30.7% of Albertan patients had diagnostic imaging within six months of their initial visit for lower back pain; a cardiac test preceded 17.9 to 35.5% of low-risk surgical procedures across Alberta, Saskatchewan, and Ontario; and 22.2% of Canadian women aged 40–49 at average-risk for breast cancer reported having a routine screening mammogram in the past two years. Conclusions The use of potentially unnecessary care appears to be common in Canada. This investigation provides methodology to facilitate future measurement efforts that may incorporate additional jurisdictions and/or unnecessary services. Electronic supplementary material The online version of this article (10.1186/s12913-019-4277-9) contains supplementary material, which is available to authorized users.

Objective To evaluate the technical efficiency of acute inpatient care at the pan-Canadian level and to explore the factors associated with inefficiency-why hospitals are not on their production frontier. Data sources/study setting Canadian Management Information System (MIS) database (CMDB) and Discharge Abstract Database (DAD) for the fiscal year of 2012-2013. Study design We use a nonparametric approach (data envelopment analysis) applied to three peer groups (teaching, large, and medium hospitals, focusing on their acute inpatient care only). The double bootstrap procedure (Simar and Wilson 2007) is adopted in the regression. Data collection/extraction methods Information on inpatient episodes of care (number and quality of outcomes) was extracted from the DAD. The cost of the inpatient care was extracted from the CMDB. Principal findings On average, acute hospitals in Canada are operating at about 75 percent efficiency, and this could thus potentially increase their level of outcomes (quantity and quality) by addressing inefficiencies. In some cases, such as for teaching hospitals, the factors significantly correlated with efficiency scores were not related to management but to the social composition of the caseload. In contrast, for large and medium nonteaching hospitals, efficiency related more to the ability to discharge patients to postacute care facilities. The efficiency of medium hospitals is also positively related to treating more clinically noncomplex patients. Conclusions The main drivers of efficiency of acute inpatient care vary by hospital peer groups. Thus, the results provide different policy and managerial implications for teaching, large, and medium hospitals to achieve efficiency gains.

BACKGROUND Patients admitted to the hospital on weekends experience worse outcomes than those admitted on weekdays. Patients with cancer may be especially vulnerable to the effects of weekend care. Our objective was to compare the care and outcomes of patients with cancer admitted urgently to the hospital on weekends and holidays versus those of patients with cancer admitted at other times. MATERIALS AND METHODS This was a retrospective study of all adult patients with cancer having an urgent hospitalization in Canada from 2010 to 2013. Patients admitted to hospital on weekends/holidays were compared with those admitted on weekdays. The primary outcome was 7-day in-hospital mortality. We also compared performance of procedures in the first 2 days of hospital admission and admission to critical care after the first 24 hours. RESULTS 290,471 hospital admissions were included. Patients admitted to hospital on weekends/holidays had an increased risk of 7-day in-hospital mortality (4.8% vs 4.3%; adjusted odds ratio [OR], 1.13; 95% CI, 1.08-1.17), corresponding to 137 excess deaths per year compared with the weekday group. This risk persisted after restricting the analysis to patients arriving by ambulance (7.1% vs 6.4%; adjusted OR, 1.11; 95% CI, 1.04-1.18). Among those who had procedures in the first 4 days of admission, fewer weekend/holiday-admitted patients had them performed in the first 2 days, for 8 of 9 common procedure groups. There was no difference in critical care admission risk after the first 24 hours. CONCLUSIONS Patients with cancer admitted to the hospital on weekends/holidays experience higher mortality relative to patients admitted on weekdays. This may result from different care processes for weekend/holiday patients, including delayed procedures. Future research is needed to identify key outcome-driving procedures, and ensure timely access to these on all days of the week.

The period immediately after discharge from hospital can potentially be high risk and a vulnerable transition point for patients. This analysis from the Canadian Institute for Health Information assessed adherence to best practices for patient follow-up in the community after hospitalization in Alberta and Saskatchewan. For three selected conditions - acute myocardial infarction, heart failure and chronic obstructive pulmonary disease - the majority of patients (77-92%) saw a physician within a month of their discharge. However, fewer patients saw a physician within the first week (35-56%).

Neonatal intensive care units (NICUs) and intensive care units (ICUs) provide care for newborns in need of specialized medical attention. Across Canada, rates of NICU/ICU admission vary. Due to the high cost of monitoring and interventions these admissions cost more than general newborn stays - whether the newborn is in a specialized NICU or in an ICU in those facilities without specialized units for newborns. This study explores the variation in NICU/ICU admissions and the characteristics of mothers and newborns associated with an increased likelihood of NICU/ICU admission. We focus further on the association between NICU/ICU admission and Caesarean section (C-section). After excluding multiple births, preterm births, small for gestational age births and those delivered by women with select complications, we find an increased risk for NICU/ICU admission for babies born by C-section as their only indication. NICU/ICU admission following C-section alone may not represent the most desirable pathway of care for these newborns.

Given the rise in obesity rates, increasing capacity for bariatric surgery has become a focus for some provincial planners. Four types of bariatric procedures are now performed in Canada; however, funding for the procedures varies by jurisdiction. This article provides an update to our previous article documenting the volume of in-patient bariatric procedures but focuses on the extent to which Canadians are increasingly receiving bariatric procedures in day surgery settings.

To assess the association of intrauterine insemination, in vitro fertilization (IVF) and ovulation induction with the risk of preeclampsia.We conducted a population based retrospective cohort study of pregnancies conceived by assisted reproductive technology (1357 exposure subjects, 5190 controls) based on 2005 Niday Perinatal Database for Ontario, Canada. All pregnancies conceived by assisted reproductive technology were identified as exposure group. Four controls were randomly matched for each exposure subject by maternal age, parity, plurality, and delivery hospital level and residence area. The risks for preeclampsia associated with intrauterine insemination, IVF, and ovulation induction were evaluated through conditional logistic regression models compared with their corresponding controls.With adjustment of maternal age, smoking during pregnancy and initiating time of prenatal care, in vitro fertilization was associated with an increased risk for preeclampsia (OR=1.78, 95% CI: 1.05, 3.06), whereas intrauterine insemination (OR=2.44, 95% CI: 0.74, 8.06) and ovulation induction (OR=1.34, 95% CI: 0.31, 5.75) was not associated with the risk for preeclampsia.There was a higher incidence of preeclampsia among pregnancies conceived by IVF, but no significant association was found in intrauterine insemination and ovulation induction.

We examined the impact of the presence of one anomalous fetus in a twin pregnancy on perinatal outcomes in the normal cotwin. Perinatal outcomes in cotwins with an anomalous twin and cotwins without an anomalous twin were compared using data from the 1995 to 1997 United States Matched Multiple Births dataset. The two groups were matched by maternal age, parity, birth order, gender, and sex concordance (1:4 matching). The risks of preterm birth, low birth weight, small-for-gestational-age birth, fetal distress, the use of assisted ventilation, low Apgar score, fetal death, neonatal death, and infant death in the 3307 normal cotwins with a twin affected by structural anomalies were significantly higher than those of the 12,813 matched cotwins without an anomalous twin. The presence of one structurally anomalous fetus in a twin pregnancy increases the risks of adverse perinatal outcomes in the cotwin without a fetal anomaly.

This study assessed the effects of repeated courses of antenatal corticosteroids on biometric characteristics, salivary cortisol, and heart function in children 6 to 10 years of age using a retrospective cohort study. Twenty-nine children whose mothers had received two or more courses of antenatal corticosteroids were identified from hospital charts. Eighty-seven children whose mothers did not receive antenatal corticosteroids were frequency matched with the exposed group by child's age, sex, and ethnicity. The body development, heart function, and salivary corticosteroid level were evaluated at 6 to 10 years of age. The percentiles of body measurements were calculated based on the 2000 Centers for Disease Control and Prevention growth charts. The general linear models were applied to assess the observed association. Decreased head circumference ( P = 0.017) and body mass index (BMI) ( P = 0.047) in children 6 to 10 years of age were associated with repeated courses of antenatal corticosteroids. Morning salivary cortisol level was lower in the exposed group than the unexposed group ( P = 0.048). No difference was found in height, weight, blood pressure, heart rate, and echocardiogram measurements between the two groups. Repeated courses of antenatal corticosteroid therapy are associated with decreased head circumference, BMI, and salivary cortisol level in children 6 to 10 years of age.

Objectives The objective of this study was to ascertain the knowledge base of Ontario maternity care providers (family physicians, obstetrician-gynaecologists, and midwives) regarding the future health risks of gestational hypertension and preeclampsia and the practices with respect to communication of these risks. Methods In 2004, all obstetricians (639) and midwives (249) in Ontario and a random sample of 600 Ontario family physicians were mailed a survey and a reminder. Non-responders were also sent a second, and in some cases, a third copy of the survey. The survey addressed areas of knowledge, reported practices, and both patient and interprofessional communication. Descriptive analysis was used for the responses. Results The overall response rate was 42%. The majority of respondents were familiar with the long-term risks of gestational hypertension and preeclampsia. Although maternity care providers stated that they inform women with these conditions about their subsequent risks and recommend follow-up, only 36% usually inform the women’s primary care providers about that subsequent risk. Only 58% of family physicians reported that they are usually informed by the maternity care providers about their patients who developed hypertension in pregnancy, compared with the 83% of maternity care providers who reported that they usually communicate this information to family physicians. Conclusion We have identified weaknesses in knowledge base and communication amongst Ontario maternity care providers that suggest that the identification and follow-up of women with hypertensive disorders of pregnancy is not occurring. These deficiencies would be amenable to directed educational activities, including reviews, presentations, and the development and implementation of guidelines.

Objective To assess the effects of pregnancy-induced hypertension on infant mortality in triplets stratified by gestational age at birth. Methods A retrospective cohort study was conducted using the linked 1995–2000 US birth/infant death database. Generalized estimating equations were used to evaluate the observed association. Results Pregnancy-induced hypertension was associated with lesser neonatal mortality (odds ration [OR]: 0.34, 95% CI: 0.21, 0.54), postneonatal mortality (OR: 0.54, 95% CI: 0.30, 0.99) and infant mortality (OR, 0.37, 95% CI: 0.25, 0.55) in triplets. It was also associated with a decreased risk of neonatal death (OR, 0.38; 95% CI, 0.21–0.67), postneonatal death (OR, 0.45; 95% CI, 0.21–0.97), and infant death (OR, 0.39; 95% CI, 0.24–0.64) in early preterm triplets, whereas the association was not significant in late preterm or in full-term triplets. Conclusion Pregnancy-induced hypertension is associated with a decreased risk of infant mortality in triplets. This effect varies with gestational age at birth.

To create prediction models of early preterm birth for singletons, twin, and triplet pregnancies.We used a historical cohort study with the 1996 birth registration data for singletons and the 1995-1997 linked birth/infant death dataset for multiple births of the United States. Preterm birth was defined as gestational age32 completed weeks. Eligible study subjects were randomly allocated to two groups: one group (80% subjects) for the creation of the prediction models, and the other group (20% subjects) for the validation of the established prediction models. Multivariate logistic regressions were used to establish the prediction models. We further assessed the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the established prediction models with different cut-off values in the validation group.The sensitivity, specificity, PPV, and NPV of the established model were 24.58, 93.54, 5.91, and 98.69%, respectively for singletons, 64.66, 57.04, 16.29, and 92.59%, respectively for twins, and 63.57, 53.58, 42.96, and 72.78%, respectively for triplets.The prediction models of early preterm birth for singleton, twin, and triplet pregnancies created by this study could be useful for obstetricians to identify women being at high risk of preterm birth at early gestation.

We assess the impacts of operative delivery for the first twins with vertex presentation on neonatal outcomes in second twins using the 1995 to 1997 twin registry data of the United States. A total of 102,554 eligible twin pairs with vertex presentation for the first twin were included in the analysis. Of these, 50,748 (49.5%) first twins had a normal vaginal delivery, 43,504 (42.4%) were delivered by cesarean section, and 8302 (8.1%) were delivered by vaginal operation (vacuum extraction or forceps). In term twins, the risks of asphyxia-related mortality (odds ratio [OR], 3.08; 95% CI, 1.07 to 8.45), newborn injury (OR, 2.10; 95% 1.39 to 3.12), low Apgar score at 5 minutes (OR, 1.49; 95% 1.24 to 1.78), and mechanical ventilation use (OR, 1.34; 95% 1.20 to 1.51) were increased in the second twins whose co-twins were delivered by vaginal operation compared with those whose co-twins who had normal vaginal delivery. In contrast, the risks of asphyxia-related mortality (OR, 0.55; 95% 0.17 to 1.57), newborn injury (OR, 0.20; 95% 0.11 to 0.34), low Apgar score at 5 minutes (OR, 0.51; 95% 0.44 to 0.60), and mechanical ventilation use (OR, 0.77; 95% 0.71 to 0.83) were decreased in the second twins whose co-twins were delivered by cesarean section compared with those whose co-twins had a normal vaginal delivery. In conclusion, vaginal operative delivery for the first twins is related to the adverse neonatal outcomes of their co-twins, whereas cesarean delivery for the first twins is associated with the beneficial neonatal outcomes of their co-twins.

Objective To assess the association between pregnancy-induced hypertension (PIH) and infant mortality. Design Retrospective cohort study. Setting Birth and infant death registration dataset of the USA. Population A total of 17 432 987 eligible, liveborn singleton births in 1995–2000. Methods Multivariate logistic regression was applied to evaluate the association between PIH and infant mortality, with adjustment of potential confounders. Main outcome measures Infant death (0–364 days) and its three components: early neonatal death (0–6 days), late neonatal death (7–27 days), and postneonatal death (28–364 days). Results There was a significant reduction in infant mortality associated with PIH in early preterm infants (OR = 0.59, 95% CI: 0.56–0.63) and in late preterm infants (OR = 0.80, 95% CI: 0.73–0.87), but a significant increase in term infants (OR = 1.08, 95% CI: 1.02–1.14). Both in early preterm and late preterm births, early neonatal mortality (OR = 0.38, 95% CI: 0.34–0.42; OR = 0.68, 95% CI: 0.61–0.77) and late neonatal mortality (OR = 0.59, 95% CI: 0.50–0.70; OR = 0.76, 95% CI: 0.61–0.96) were decreased in infants born to mothers with PIH compared with those born to mothers with normal blood pressure. The PIH-associated reduction in neonatal mortality among preterm singletons was stronger in small-for-gestational-age infants than in normal growth infants and stronger in infants born to nulliparous women than in those born to multiparous women. Conclusions PIH is associated with lower risk of infant death in preterm births but higher risk in term births.

Previous studies have suggested that environmental lead exposure increases the risk of hypertension in the general population. In this article, the authors used the 1998 linked birth/infant death database of the United States to examine the association between environmental lead level and the occurrence of pregnancy-induced hypertension (PIH). Yearly summaries of environmental lead levels were abstracted from the US Environmental Protection Agency's air pollution databases, and linked with birth/infant death records by state codes. Generalized estimating equations (GEEs) were used to evaluate the odds ratios of PIH associated with environmental lead measured at ecological levels, with adjustment for maternal age, race, education level, marital status, parity, and adequacy of prenatal care measured at individual levels, stratified by maternal cigarette smoking. A total of 2,994,072 women pregnant in 1998 were included in this study. With the first quartile of lead level as the reference group, the odds ratio for PIH among all study subjects in the second quartile of seasonal average lead level at conception was 1.07 (95% CI: 1.05–1.08), and odds ratios in the third and fourth quartiles were 1.22 (95% CI: 1.20–1.25) and 1.16 (95% CI: 1.15–1.18), respectively. The odds ratios for the second, third, and fourth quartiles of seasonal average lead level at birth were 1.07 (95% CI: 1.05–1.09), 1.21 (95% CI: 1.19–1.23), and 1.15 (95% CI: 1.13–1.17), respectively. The risk of PIH increased by 4% per 0.05 μg/m 3 increase in seasonal average lead level at conception and birth, in both smokers and nonsmokers. These results suggest that higher environmental lead levels increase the risk of PIH.

Multiple gestations are associated with an increased risk of maternal morbidity and mortality independent of maternal age. Previous reports by the Canadian Institute for Health Information established the overall association between advanced maternal age and complications related to pregnancy and childbirth. This article takes a more focused look at the association between advanced maternal age and maternal outcomes in multiple gestation pregnancies. We found, for mothers aged 35 years and older carrying multiples--after adjusting for mothers' parity, neighbourhood income and residence (rural/urban)--an increased risk of pregnancy complications including pre-existing hypertension, gestational hypertension, pre-eclampsia/eclampsia, gestational diabetes and placenta previa and an increased risk for Caesarean delivery.

A recent Canadian Institute for Health Information report on all-cause readmission identified that cancer patients had higher-than-average readmission rates. This study provides further insight on the experience of cancer patients, exploring the risk factors associated with readmission at patient, hospital and community levels. An analysis showed that patient characteristics, including the reason for initial hospitalization, sex, co-morbidity levels, admission through the emergency department and the number of previous acute care admissions, were associated with readmission for cancer patients. In addition, we found that the readmission rate for these patients varied by hospital size and whether the patients lived in rural or urban locations.

Objective To examine the possible association between oral contraceptive use and adverse birth outcomes. Study design We conducted a population-based cohort study of pregnant women who used oral contraceptives within 3 months before their last menstrual period. Subjects were divided into three groups, according to the interval (0–30, 31–60, and 61–90 days) between the dispensing date and their last menstrual period. For each exposed subject, 4 subjects without exposure to oral contraceptives were individually matched by infant's year of birth and plurality and by mother's age and parity. Results Oral contraceptive use within 30 days prior to the last menstrual period was associated with increased risks of very low birth weight (OR: 3.24, 95% CI: 1.18, 8.92), low birth weight (OR: 1.93, 95% CI: 1.17, 3.20), and preterm birth (OR: 1.61, 95% CI: 1.01, 2.55); however, oral contraceptive use 31–90 days prior to the last menstrual period did not increase the risk of low birth weight or preterm birth. Conclusion Our results indicate the use of oral contraceptives near the time of conception may be associated with an increased risk of low birth weight and preterm birth.

Most previous studies on the effect of paternal age have focused on the association of advanced paternal age with congenital anomalies. The objective of this study was to determine whether paternal age is associated with the risk of adverse birth outcomes independent of maternal confounders. We carried out a retrospective cohort study of 2 614 966 live singletons born to married nulliparous women aged 20-29 years between 1995 and 2000 in the USA. Multiple logistic regressions were applied to estimate the independent effect of paternal age on adverse birth outcomes. Compared with infants born to fathers aged 20-29 years infants fathered by teenagers (less than 20 years old) had an increased risk of preterm birth [odds ratio (OR) = 1.15 95% confidence interval (CI): 1.10 1.20] low birth weight (OR = 1.13 95% CI: 1.08 1.19) small-for-gestational-age births (OR = 1.17 95% CI: 1.13 1.22) low Apgar score (OR = 1.13 95% CI: 1.01 1.27) neonatal mortality (OR = 1.22 95% CI: 1.01 1.49) and post-neonatal mortality (OR = 1.41 95% CI: 1.09 1.82). Advanced paternal age (greater than or equal to 40 years) was not associated with the risk of adverse birth outcomes. Teenage fathers carry an increased risk of adverse birth outcomes that is independent of maternal confounders whereas advanced paternal age is not an independent risk factor for adverse birth outcomes. (authors)

To compare the effects of new-onset hypertension (NOH) in late pregnancy on fetal growth in singletons and twins.A retrospective cohort study was conducted to evaluate the effect of NOH on fetal growth in 17, 720, 900 singletons and 463, 104 twins born in the United States between 1995 and 2000.NOH was associated with lower mean birth weight in both preterm and term singletons. Increased risk of low birth weight and decreased risk of high birth weight was associated with NOH in preterm and term singletons. NOH was associated with increased risk for small-for-gestational-age (SGA) births and decreased risk for large-for-gestational-age (LGA) births in preterm singletons, whereas it was associated with increased risk of both SGA and LGA births in term singletons. NOH was associated with higher mean birth weight in early preterm twins, and lower mean birth weight in term twins. Decreased risk for low birth weight was found in the NOH group among early preterm twins, and increased risk for low birth weight in term twins. NOH was associated with increased risk of SGA births and decreased risk for large-for-gestational-age (LGA) births in early preterm twins, while increased risk of SGA births in term twins.NOH is associated with slower fetal growth in singletons delivered at different gestational ages, but the effect varies in twins depending on gestational age at delivery with faster growth in early preterm twins.

BACKGROUND: Teenage pregnancy may be associated with some forms of congenital anomalies. The objective of this study was to identify the types of congenital anomalies associated with teenage pregnancy. METHODS: We carried out a retrospective cohort study of 5 542 861 nulliparous pregnant women younger than 35 years of age with a live singleton birth between 1995 and 2000 in the USA. RESULTS: Compared with adult pregnancy (20–34 years old), and after adjustment for confounding variables, teenage pregnancy (13–19 years old) was associated with increased risk of central nervous system anomalies [odds ratio (OR) 1.08; 95% confidence interval (CI): 1.01, 1.16], gastrointestinal anomalies (OR: 1.39; 95% CI: 1.31, 1.49) and musculoskeletal/integumental anomalies (OR: 1.06; 95% CI: 1.03, 1.10). The teenage pregnancy associated increase in risk for central nervous system anomalies was mainly attributable to anomalies other than anencephalus, spina bifida/meningocele and hydrocephalus and microcephalus; for gastrointestinal anomalies the risk was mainly attributable to omphalocele/gastroschisis; and for musculoskeletal/integumental anomalies the risk was mainly attributable to cleft lip/palate and polydactyly/syndactyly/adactyly. No increased risk was found for circulatory/respiratory anomalies, urogenital anomalies, or Down’s syndrome. CONCLUSIONS: Teenage pregnancy increases the risks of congenital anomalies in central nervous, gastrointestinal and musculoskeletal/integumental systems.

Background: Previous studies have found that inadequate prenatal care was associated with increased neonatal mortality in the general pregnant women. Aims: To examine the association between adequacy of prenatal care and neonatal mortality in the presence and absence of antenatal high-risk conditions. Methods: We conducted a retrospective cohort study of infants based on 1995–2000 vital statistics data in the USA. The relative risk for neonatal death associated with adequacy of prenatal care was estimated by multivariate logistic regressions with adjustment of confounding factors. Results: Inadequate prenatal care was associated with increased neonatal mortality when pregnancies were complicated by anaemia, cardiac disease, lung disease, chronic hypertension, diabetes, renal disease, pregnancy-induced hypertension, and previous preterm/small-for-gestational-age birth. The observed association also existed in the absence of these antenatal high-risk conditions. Overutilisation of prenatal care was associated with increased risk of neonatal deaths in both the presence and the absence of antenatal high-risk conditions. When gestational age at delivery and birthweight were further adjusted, the observed association between inadequate prenatal care and neonatal mortality was not significant in pregnancies with various high-risk conditions. Conclusions: Inadequate prenatal care is associated with increased neonatal death in both the presence and the absence of antenatal high-risk conditions. The observed association between inadequate prenatal care and neonatal mortality may be mediated by increased risk of preterm delivery and low birthweight in these pregnancies. Overutilisation of prenatal care is associated with potential risks for fetal and neonatal development, leading to increased neonatal mortality.

Objective To determine the potential pathway of the association between teenage pregnancy and neonatal and postneonatal mortality. Study Design and setting We carried out a retrospective cohort study of 4,037,009 nulliparous pregnant women under 25 years old who had a live singleton birth during 1995 to 2000, based on linked birth and infant death data set of the United States. Results Teenage pregnancy (10–19 years old) was associated with increased neonatal mortality (odds ratio [OR]: 1.20, 95% confidence interval [CI] = 1.16–1.24) and postneonatal mortality (OR: 1.47, 95% CI = 1.41–1.54) after adjustment for potential confounders. With further adjustment for weight gain during pregnancy, teenage pregnancy was still associated with increased risk of neonatal (OR: 1.23, 95% CI = 1.19–1.28) and postneonatal mortality (OR: 1.48, 95% CI = 1.42–1.55). When adjustment was made for gestational age at birth, there was no association of teenage pregnancy with neonatal mortality (OR: 0.98, 95% CI = 0.95–1.02), whereas there was significant association with postneonatal mortality (OR: 1.40, 95% CI = 1.34–1.46). Conclusion The increased risk of neonatal death associated with teenage pregnancy is largely attributable to higher risk of preterm births, whereas increased postneonatal mortality is independent of the known confounders and gestational age at birth.

Objective To assess the effect of pregnancy-induced hypertension (PIH) on infant mortality in different birthweight centiles (small for gestational age [SGA], appropriate for gestational age [AGA], and large for gestational age [LGA]) and gestational ages (early preterm, late preterm, and full term). Design Retrospective cohort study. Setting Linked birth and infant death data set of USA between 1995 and 2000. Population A total of 17 464 560 eligible liveborn singleton births delivered after 20th gestational week. Methods Multivariate logistic regression models were applied to evaluate the association between PIH and infant mortality, with adjustment of potential confounders stratified by birthweight centiles and gestational age. Main outcome measure Infant death (0–364 days) and its three components: early neonatal death (0–6 days), late neonatal death (7–27 days), and postneonatal death (28–364 days). Results PIH was associated with decreased risks of infant mortality, early neonatal mortality, and late neonatal mortality in both preterm and term SGA births, and PIH was associated with lower postneonatal mortality in preterm SGA births. PIH was associated with decreased risks of infant mortality, early neonatal mortality, late neonatal mortality and postneonatal mortality in preterm AGA births. Decreased risk of infant mortality and early neonatal mortality was associated with PIH in early preterm LGA births. Conclusions The association between PIH and infant mortality varies depending on different birthweight centiles, gestational age, and age at death. PIH is associated with a decreased risk of infant mortality in SGA births, preterm AGA births, and early preterm LGA births.

Whether the association between teenage pregnancy and adverse birth outcomes could be explained by deleterious social environment, inadequate prenatal care, or biological immaturity remains controversial. The objective of this study was to determine whether teenage pregnancy is associated with increased adverse birth outcomes independent of known confounding factors.We carried out a retrospective cohort study of 3,886,364 nulliparous pregnant women25 years of age with a live singleton birth during 1995 and 2000 in the United States.All teenage groups were associated with increased risks for pre-term delivery, low birth weight and neonatal mortality. Infants born to teenage mothers aged 17 or younger had a higher risk for low Apgar score at 5 min. Further adjustment for weight gain during pregnancy did not change the observed association. Restricting the analysis to white married mothers with age-appropriate education level, adequate prenatal care, without smoking and alcohol use during pregnancy yielded similar results.Teenage pregnancy increases the risk of adverse birth outcomes that is independent of important known confounders. This finding challenges the accepted opinion that adverse birth outcome associated with teenage pregnancy is attributable to low socioeconomic status, inadequate prenatal care and inadequate weight gain during pregnancy.

To assess the association between new-onset hypertension in late pregnancy (NOH) and fetal and infant mortality in early preterm, late preterm, and full-term twins.We conducted a retrospective cohort study in 275, 316 twins in 1995-1997 based on multiple birth registration dataset of USA. Generalized estimating equations (GEEs) was used to evaluate the odds ratios (OR) of fetal and infant death (at individual level) associated with NOH, with adjustment of potential confounders at both twin set level and individual level.The risks for early neonatal death (OR = 0.52, 95% CI: 0.36, 0.76) and late neonatal death (OR = 0.57, 95% CI: 0.37, 0.87) were decreased in early preterm twins born to mothers with NOH compared with early preterm twins born to mothers with normal blood pressure. The decreased risks for fetal death (OR = 0.40, 95% CI: 0.30, 0.53; OR = 0.46, 95% CI: 0.53, 0.65) and infant death (OR = 0.35, 95% CI: 0.28, 0.44; OR = 0.68, 95% CI: 0.51, 0.91) were associated with NOH in both early and late preterm twins, whereas no association between NOH and fetal/infant mortality were observed in full-term twins.NOH is associated with lower risk of fetal death and infant death in preterm twins.

To examine the association between maternal age, paternal age, and new-onset hypertension in late pregnancy.We carried out a retrospective cohort study of 9,302,675 pregnant women with live births in the United States between 1995 and 1998. Maternal and paternal ages were analyzed together using "couple age" in multivariate logistic regression models to reduce colinearity between maternal age and paternal age. The effect of paternal age was also analyzed with stratification of maternal age.Compared with couples with both a maternal and paternal age of 20 to 34 years, an older maternal age (above 35 years) was associated with an increased risk for new-onset hypertension, except for couples with a very young father (below 20 years). Younger maternal age (below 20 years) was associated with a decreased risk for new-onset hypertension, except for couples with a very old father (above 45 years). There was no significant association between paternal age and new-onset hypertension with stratification of maternal age.Increased risk for new-onset hypertension in late pregnancy is significantly associated with advancing maternal age, whereas there is no association between paternal age and new-onset hypertension in late pregnancy.

Although previous studies have found that maternal smoking decreases the risk of pregnancy-induced hypertension (PIH), the difference of this effect between primiparous and multiparous women has not been well studied and the results of the exposure-response relationships between maternal smoking and PIH are inconsistent. No previous study has specifically examined the relationship between maternal smoking and eclampsia.We analysed data from a population-based retrospective cohort study of 3 153 944 singleton pregnancies in the US. The data were derived from the national linked birth/infant mortality database for 1998. Multiple logistic regressions were used to describe the relationship between cigarette smoking and PIH and eclampsia.The adjusted odds ratios (ORs) [95% confidence intervals (95% CIs)] for PIH were 0.80 (0.77-0.83) for primiparous women and 0.81 (0.78-0.83) for multiparous women among smokers compared with non-smokers. The corresponding adjusted ORs (95% CIs) for eclampsia were 0.74 (0.66-0.82) and 0.75 (0.68-0.83), respectively. For PIH, the adjusted OR (95% CI) for smokers vs non-smokers were 0.82 (0.79-0.86), 0.81 (0.78-0.83), 0.80 (0.77-0.83), and 0.88 (0.79-0.98), respectively, for 1-5, 6-10, 11-20, and20 cigarettes per day (test for trend: P = 0.86). The corresponding figures for eclampsia were 0.85 (0.75-0.95), 0.74 (0.66-0.82), 0.68 (0.58-0.78), and 0.73 (0.49-1.04), respectively (test for trend: P = 0.02).Maternal cigarette smoking decreases the risk of PIH and eclampsia, with a significant inverse exposure-response relationship apparent for eclampsia.

Objective The objective of the study was to evaluate the association between folic acid supplementation in early second trimester and the risk of developing preeclampsia. Study Design We carried out a prospective cohort study between October 2002-December 2005. We recruited women who had their prenatal care visit (12-20 weeks’ gestation) at the Ottawa Hospital and Kingston General Hospital. All charts for participants with a diagnosis of preeclampsia were audited and blindly adjudicated by 4 study investigators to validate the diagnosis. Results A total of 2951 pregnant women were included in the final analysis. Supplementation of multivitamins containing folic acid was associated with increased serum folate (on average 10.51 μmol/L), decreased plasma homocysteine (on average 0.39 μmol/L), and reduced risk of preeclampsia (adjusted odds ratio, 0.37; 95% confidence interval, 0.18-0.75). Conclusion Supplementation of multivitamins containing folic acid in the second trimester is associated with reduced risk of preeclampsia.

Objective The objective of the study was to evaluate the association between folic acid supplementation in early second trimester and the risk of developing preeclampsia. Study Design We carried out a prospective cohort study between October 2002-December 2005. We recruited women who had their prenatal care visit (12-20 weeks’ gestation) at the Ottawa Hospital and Kingston General Hospital. All charts for participants with a diagnosis of preeclampsia were audited and blindly adjudicated by 4 study investigators to validate the diagnosis. Results A total of 2951 pregnant women were included in the final analysis. Supplementation of multivitamins containing folic acid was associated with increased serum folate (on average 10.51 μmol/L), decreased plasma homocysteine (on average 0.39 μmol/L), and reduced risk of preeclampsia (adjusted odds ratio, 0.37; 95% confidence interval, 0.18-0.75). Conclusion Supplementation of multivitamins containing folic acid in the second trimester is associated with reduced risk of preeclampsia.