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To identify determinants of cesarean delivery (CD) and examine associations between mode of delivery (MOD) and maternal and perinatal outcomes.We conducted a retrospective analysis of a Canadian multicentre birth cohort derived from provincial data collected in 2008/2009. Maternal and perinatal characteristics and outcomes were compared between vaginal and cesarean birth and between the following MOD subgroups: spontaneous vaginal delivery (VD), assisted VD, planned cesarean delivery (CD), and intrapartum CD. Multivariate regression identified determinants of CD and the effects of MOD and previous CD on maternal and perinatal outcomes.The cohort included 264 755 births (72.1% VD and 27.9% CD) from 91 participating institutions. Determinants of CD included maternal age, parity, previous CD, chronic hypertension, diabetes, urinary tract infection or pyelonephritis, gestational hypertension, vaginal bleeding, labour induction, pre-term gestational age, low birth weight, large for gestational age, malpresentation, and male sex. CD was associated with greater risk of maternal and perinatal morbidity and mortality. Subgroup analysis demonstrated higher risk of adverse pregnancy outcomes with assisted VD and intrapartum CD than spontaneous VD. Planned CD reduced the risk of obstetric wound hematoma and perinatal mortality but increased maternal and neonatal morbidity. Previous CD increased the risk of maternal and neonatal morbidity among multiparous women.The CD rate in Canada is consistent with global trends reflecting demographic and obstetric intervention factors. The risk of adverse pregnancy outcomes with CD warrants evaluation of interventions to safely prevent nonessential cesarean birth.

Objective To assess the risk of birth defects in infants born after assisted human reproduction (AHR). Design Retrospective cohort study. Setting Niday Perinatal Database for the province of Ontario, 82 sites, both primary and tertiary centers. Patient(s) In 2005, information about reproductive assistance was reported for 61,569 deliveries. Intervention(s) The prevalence of birth defects diagnosed in the prenatal period or at birth was estimated for all types of AHR together and then by type of procedure. Main Outcome Measure(s) The excess risks of birth defects by AHR were calculated by unconditional logistic regressions using spontaneously conceived pregnancies as the reference and were expressed by odds ratio and 95% confidence intervals and adjusted for maternal age, smoking, infant gender, gestation, and parity. Result(s) The prevalence of birth defects with AHR procedures was 2.91%, which was 1.55-fold higher (95% confidence interval [CI], 1.03–2.38) than in the non-AHR population (1.86%). Specific anomalies that increased with AHR were gastrointestinal (odds ratio [OR], 9.85; 95% CI, 3.44–28.44), cardiovascular (OR, 2.30; 95% CI, 1.11–4.77), and musculoskeletal defects (OR, 1.54; 95% CI, 0.48–4.94). The risks of birth defects by types of AHR were 2.35% for ovulation induction, 2.89% for IUI, and 3.45% for IVF. Conclusion(s) There is a significant increased risk of birth defects associated with AHR, and the risk is higher in IVF and IUI. The potential risk of anomalies associated with AHR may be considered in the counseling that is offered to infertile couples.

Background: Explicit patient consent requirements in privacy laws can have a negative impact on health research, leading to selection bias and reduced recruitment. Often legislative requirements to obtain consent are waived if the information collected or disclosed is de-identified. Objective: The authors developed and empirically evaluated a new globally optimal de-identification algorithm that satisfies the k-anonymity criterion and that is suitable for health datasets. Design: Authors compared OLA (Optimal Lattice Anonymization) empirically to three existing k-anonymity algorithms, Datafly, Samarati, and Incognito, on six public, hospital, and registry datasets for different values of k and suppression limits. Measurement: Three information loss metrics were used for the comparison: precision, discernability metric, and non-uniform entropy. Each algorithm's performance speed was also evaluated. Results: The Datafly and Samarati algorithms had higher information loss than OLA and Incognito; OLA was consistently faster than Incognito in finding the globally optimal de-identification solution. Conclusions: For the de-identification of health datasets, OLA is an improvement on existing k-anonymity algorithms in terms of information loss and performance.

Objective To ascertain differences in pregnancy outcomes between women with diabetes subtypes (type 1 [DM1], type 2 [DM2], women with gestational [GDM])] and non-diabetic women within a large Canadian population. Methods We performed a retrospective multi-cohort analysis of all obstetrical deliveries that occurred in the province of Ontario between April 1, 2005, and March 31, 2006. Data were extracted from the Ontario Niday Perinatal Database. Results Increased rates of major negative maternal and perinatal outcomes (i.e. preterm delivery, Caesarean section, pregnancy-induced hypertension/preeclampsia) occurred in women with DM1. Both DM1 and GDM subtypes were associated with the greatest risk of macrosomia, shoulder dystocia, and congenital anomalies. DM2 did not demonstrate an association with an increased risk of congenital malformations and stillbirth. Conclusion Diabetes in pregnancy, irrespective of subtype, predisposes women to poorer outcomes than those of the general obstetric population. However, this large population analysis is consistent with previous studies in showing that the adversity remains greatest for women with type 1 diabetes.

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.

to assess the association between neighbourhood family income and adverse birth outcomes.we conducted a retrospective cohort study of 334 231 singleton births during 2004 and 2006 based on the Niday Perinatal Database from Ontario. Median neighbourhood family incomes from the 2001 Canadian census were linked with the Niday Perinatal Database by dissemination areas. Generalized estimating equations were applied to estimate the odds ratios of adverse birth outcomes associated with lower neighbourhood income, with adjustment for maternal confounding variables at the individual level.compared with the highest neighbourhood income quintile, mothers from the lowest quintile were at increased risk of having small for gestational age neonates (OR 1.51; 95% CI 1.46 to 1.57), low birth weight (OR 1.43; 95% CI 1.36 to 1.50), preterm birth (OR 1.17; 95% CI 1.12 to 1.23), low Apgar score (7) at five minutes (OR 1.32; 95% CI 1.21 to 1.44), and stillbirth (OR 1.39; 95% CI 1.19 to 1.62). The risks of women from the lowest income quintiles delivering a macrosomic baby (OR 0.81; 95% CI 0.79 to 0.84) or a large for gestational age baby (OR 0.82; 95% CI 0.80 to 0.85) were significantly decreased. No difference in risk of congenital anomaly was found among different income quintiles.a lower level of neighbourhood income is associated with increased risks of small for gestational age babies, low birth weight, preterm birth, low Apgar score at five minutes, and stillbirth.

Background A common disclosure control practice for health datasets is to identify small geographic areas and either suppress records from these small areas or aggregate them into larger ones. A recent study provided a method for deciding when an area is too small based on the uniqueness criterion. The uniqueness criterion stipulates that an the area is no longer too small when the proportion of unique individuals on the relevant variables (the quasi-identifiers) approaches zero. However, using a uniqueness value of zero is quite a stringent threshold, and is only suitable when the risks from data disclosure are quite high. Other uniqueness thresholds that have been proposed for health data are 5% and 20%. Methods We estimated uniqueness for urban Forward Sortation Areas (FSAs) by using the 2001 long form Canadian census data representing 20% of the population. We then constructed two logistic regression models to predict when the uniqueness is greater than the 5% and 20% thresholds, and validated their predictive accuracy using 10-fold cross-validation. Predictor variables included the population size of the FSA and the maximum number of possible values on the quasi-identifiers (the number of equivalence classes). Results All model parameters were significant and the models had very high prediction accuracy, with specificity above 0.9, and sensitivity at 0.87 and 0.74 for the 5% and 20% threshold models respectively. The application of the models was illustrated with an analysis of the Ontario newborn registry and an emergency department dataset. At the higher thresholds considerably fewer records compared to the 0% threshold would be considered to be in small areas and therefore undergo disclosure control actions. We have also included concrete guidance for data custodians in deciding which one of the three uniqueness thresholds to use (0%, 5%, 20%), depending on the mitigating controls that the data recipients have in place, the potential invasion of privacy if the data is disclosed, and the motives and capacity of the data recipient to re-identify the data. Conclusion The models we developed can be used to manage the re-identification risk from small geographic areas. Being able to choose among three possible thresholds, a data custodian can adjust the definition of "small geographic area" to the nature of the data and recipient.

Objective We sought to examine the difference in use of labor epidural analgesia among women from different neighborhood socioeconomic groups. Study Design Neighborhood socioeconomic variables from the 2001 Canadian Census were linked to singleton vaginal births from the Niday perinatal database (2004–2006) in Ontario, Canada. Births were divided into income and education groups by quintiles. Generalized estimating equations were employed to evaluate the association between labor epidural and neighborhood socioeconomic status. Supplementary analysis was conducted after stratifying data by hospital types. Results Compared with those from the richest neighborhood, women from the poorest quintile were the least likely to receive labor epidural analgesia (odds ratio [OR], 0.59; 95% confidence interval [CI], 0.58–0.61). The differences were smallest in teaching hospitals (OR, 0.73; 95% CI, 0.67–0.79) and largest in small community hospitals (OR, 0.57; 95% CI, 0.50–0.64). Similar association was found in neighborhood education quintiles. Conclusion The use of labor epidural analgesia is decreased with decreasing neighborhood economic and education levels.

To assess the utilization of health care services by pregnant women affected by preeclampsia (PE).Population-based study.Perinatal partnership hospitals in Ontario.Obstetric deliveries in 2005 Canadian province of Ontario (about 95% of births).For each PE case, four subjects without PE matched by age, parity, plurality, and hospital at childbirth were chosen as the controls. We compared the utilization of intra-partum care services and infant outcomes between the two groups. We also estimated the extra costs to the health care system in Ontario for caesarean delivery and caring of extremely low birth weight infants attributable to PE during the neonatal period and in the first 2 years of life.Cesarean delivery, hospital stay, extremely low birth weight infants, cost.Of the 120,611 obstetric deliveries included in this analysis, 1240 (1.3%) were diagnosed with PE. Patients with PE and matched controls were similar in maternal age, parity, and other demographic characteristics. Compared with study subjects without PE, those with PE had increased uses of spinal anesthesia, maternal transfer, Cesarean delivery, labour induction, neonatal transfer, newborn resuscitation, longer hospital stay for childbirth, and higher rates of preterm births and low birth weight. The extra costs to the health care system for cesarean delivery and caring of extremely low-birth-weight infants attributable to PE during the neonatal period and in the first 2 years of life in Ontario were $0.5 millions, 3.1 millions, and $5.1 million per year, respectively, if we use the reported PE rate in this database.PE is associated with substantially increased costs to the health care system.