Effects of the ARRIVE (A Randomized Trial of Induction Versus Expectant Management) Trial on Elective Induction and Obstetric Outcomes in Term Nulliparous Patients.

OBJECTIVE: To evaluate the effect of publication of the ARRIVE (A Randomized Trial of Induction Versus Expectant Management) trial on perinatal outcomes in singleton, term, nulliparous patients. METHODS: An interrupted time series analysis was performed using clinical data for nulliparous singleton births at 39 weeks of gestation or later at 13 hospitals in the Northwest region of the United States (January 2016-December 2020). A modified Poisson regression was used to model time trends and changes after the ARRIVE trial (August 9, 2018). Outcomes of interest were elective induction, unplanned cesarean births, hypertensive disorders of pregnancy, a composite of perinatal adverse outcomes, and neonatal intensive care unit admissions. RESULTS: The analysis included 28,256 births (15,208 pre-ARRIVE and 13,048 post-ARRIVE). The rate of elective labor induction was 3.6% during the pre-ARRIVE period (January 2016-July 2018) and 10.8% post-ARRIVE (August 2018-December 2020). In the interrupted time series analysis, elective induction increased by 42% (relative risk [RR] 1.42; 95% CI 1.18-1.71) immediately after the ARRIVE trial publication. Thereafter, the trend was unchanged compared with the pre-ARRIVE period. There was no statistically significant change in cesarean birth (RR 0.96; 95% CI 0.89-1.04) or hypertensive disorders of pregnancy (RR 0.91; 95% CI 0.79-1.06) immediately after the trial, and no change in trend. After the ARRIVE trial, there was no immediate change in adverse perinatal outcomes, but a statistically significant increase in trend of adverse perinatal events (1.03; 95% CI 1.01-1.05) when compared with a declining trend observed in the pre-ARRIVE period. CONCLUSION: Publication of the ARRIVE trial was associated with an increase in elective induction, and no change in cesarean birth or hypertensive disorders of pregnancy in singleton nulliparous patients giving birth at 39 weeks or later. There was a flattening of the pre-ARRIVE decreasing trend in perinatal adverse events.

Expanding midwifery care in the United States: Implications for clinical outcomes and cost.

BACKGROUND: This study compared clinical and financial outcomes for low-risk birthing people between those attended by midwives and those attended by obstetricians during hospital births. METHODS: We conducted a retrospective cohort analysis of births from January 1, 2016 to December 31, 2020 at hospitals participating in a perinatal quality improvement collaborative, Obstetrical Care Outcomes Assessment Program (OB COAP), in the Northwest region of the United States and estimated risk ratios using a multivariate regression approach with a modified Poisson binomial for mode of delivery, labor interventions, and newborn outcomes comparing midwife-led to obstetrician-led care. Using publicly available data on average costs of vaginal and cesarean births, we then extrapolated the cost differences in care between midwives and obstetricians. RESULTS: Births in the midwife group were less likely to be associated with induction (17.6% vs. 20.3% RR 0.74; 95% CI 0.70-0.78), epidural use (58.9% vs. 76.3% RR 0.78; 95% CI 0.77-0.80), and episiotomy (2.2% vs. 3.4% RR 0.68; 95% CI 0.58-0.81). Cesarean birth was also lower in the midwifery group (7.8% vs. 12.3% RR 0.68, 95% CI 0.62-0.73), without a corresponding increase in risk in adverse neonatal outcomes. We estimated that expanding midwifery care to 100% of low-risk births across the United States could save as much as $340 million per year. CONCLUSIONS: Midwifery care is associated with a lower risk of cesarean birth and other interventions versus care provided by obstetricians and is therefore likely lower-cost.

The effect of changing screening practices and demographics on the incidence of gestational diabetes in British Columbia, 2005-2019.

BACKGROUND: Rates of gestational diabetes are reported to be increasing in many jurisdictions, but the reasons for this are poorly understood. We sought to evaluate the relative contribution of screening practices for gestational diabetes (including completion and methods of screening) and population characteristics to risk of gestational diabetes in British Columbia, Canada, from 2005 to 2019. METHODS: We used a population-based cohort from a provincial registry of perinatal data, linked to laboratory billing records. We used data on screening completion, screening method (1-step 75-g glucose test or 2-step approach of 50-g glucose screening test, followed by a diagnostic test for patients who screen positive) and demographic risk factors. We modelled predicted annual risk for gestational diabetes, sequentially adjusted for screening completion, screening method and risk factors. RESULTS: We included 551 457 pregnancies in the study cohort. The incidence of gestational diabetes more than doubled over the study period, from 7.2% in 2005 to 14.7% in 2019. Screening completion increased from 87.2% in 2005 to 95.5% in 2019. Use of 1-step screening methods increased from 0.0% in 2005 to 39.5% in 2019 among those who were screened. Unadjusted models estimated a 2.04 (95% confidence interval [CI] 1.94-2.13) increased risk of gestational diabetes in 2019 (v. 2005). This increase was 1.89 (95% CI 1.81-1.98) after accounting for the rise in screening completion and 1.34 (95% CI 1.28-1.40) after accounting for changes in screening methods. Further accounting for demographic risk factors (e.g., age, body mass index, prenatal care) had a small impact (increase of 1.25, 95% CI 1.19-1.31). INTERPRETATION: Most of the observed increase in the incidence of gestational diabetes was attributable to changes in screening practices (primarily changes in screening methods) rather than changing population factors. Our findings highlight the importance of understanding variation in screening practices when monitoring incidence rates for gestational diabetes.

Weight gain in pregnancy and infant birthweight after the onset of the COVID-19 pandemic: an interrupted time series analysis.

BACKGROUND: Increased weight gain and decreased physical activity have been reported in some populations since the coronavirus disease 2019 (COVID-19) pandemic, but this has not been well characterized in pregnant populations. OBJECTIVES: Our objective was to characterize the impact of the COVID-19 pandemic and associated countermeasures on pregnancy weight gain and infant birthweight in a US cohort. METHODS: Washington State pregnancies and births (1 January, 2016 to 28 December, 2020) from a multihospital quality improvement organization were examined for pregnancy weight gain, pregnancy weight gain z-score adjusted for pregestational BMI and gestational age, and infant birthweight z-score, using an interrupted time series design that controls for underlying time trends. We used mixed-effect linear regression models, controlled for seasonality and clustered at the hospital level, to model the weekly time trends and changes on 23 March, 2020, the onset of local COVID-19 countermeasures. RESULTS: Our analysis included 77,411 pregnant people and 104,936 infants with complete outcome data. The mean pregnancy weight gain was 12.1 kg (z-score: -0.14) during the prepandemic time period (March to December 2019) and increased to 12.4 kg (z-score: -0.09) after the onset of the pandemic (March to December 2020). Our time series analysis found that after the pandemic onset, the mean weight gain increased by 0.49 kg (95% CI: 0.25, 0.73 kg) and weight gain z-score increased by 0.080 (95% CI: 0.03, 0.13), with no changes in the baseline yearly trend. Infant birthweight z-scores were unchanged (-0.004; 95% CI: -0.04, 0.03). Overall, the results were unchanged in analyses stratified by pregestational BMI categories. CONCLUSIONS: We observed a modest increase in weight gain after the onset of the pandemic among pregnant people but no changes in infant birthweights. This weight change could be more important in high BMI subgroups.

Validation of Insurance Billing Codes for Monitoring Antenatal Screening.

BACKGROUND: Prevalence statistics for pregnancy complications identified through screening such as gestational diabetes usually assume universal screening. However, rates of screening completion in pregnancy are not available in many birth registries or hospital databases. We validated screening-test completion by comparing public insurance laboratory and radiology billing records with medical records at three hospitals in British Columbia, Canada. METHODS: We abstracted a random sample of 140 delivery medical records (2014-2019), and successfully linked 127 to valid provincial insurance billings and maternal-newborn registry data. We compared billing records for gestational diabetes screening, any ultrasound before 14 weeks gestational age, and Group B streptococcus screening during each pregnancy to the gold standard of medical records by calculating sensitivity and specificity, positive predictive value, negative predictive value, and prevalence with 95% confidence intervals (CIs). RESULTS: Gestational diabetes screening (screened vs. unscreened) in billing records had a high sensitivity (98% [95% CI = 93, 100]) and specificity (>99% [95% CI = 86, 100]). The use of specific glucose screening approaches (two-step vs. one-step) were also well characterized by billing data. Other tests showed high sensitivity (ultrasound 97% [95% CI = 92, 99]; Group B streptococcus 96% [95% CI = 89, 99]) but lower negative predictive values (ultrasound 64% [95% CI = 33, 99]; Group B streptococcus 70% [95% CI = 40, 89]). Lower negative predictive values were due to the high prevalence of these screening tests in our sample. CONCLUSIONS: Laboratory and radiology insurance billing codes accurately identified those who completed routine antenatal screening tests with relatively low false-positive rates.

Trends in Gestational Diabetes Screening Practices in British Columbia from 2005-2019.

OBJECTIVES: To examine trends in the frequency and method (one-step vs. two-step) of gestational diabetes mellitus (GDM) screening in British Columbia (BC), Canada, across subgroups of pregnant individuals in the context of changing local and national clinical practice guidelines. METHODS: We conducted a retrospective cohort study using de-identified, linked perinatal and laboratory billing data. We included all pregnancies delivered in BC after 28 weeks gestation, with screening dates between June 2004 and May 2019. We calculated the prevalence of each screening method with 95% CI overall and over time, and we examined screening practices in subgroups and different geographic regions. In October 2010, BC began recommending a one-step method; therefore, we examined time periods relative to this and other Canadian guideline changes. RESULTS: Screening completion increased over the study period, from 88% in 2004 to 96% in 2019. After a guideline change in 2010, use of one-step screening increased sharply from 2.0% (95% CI 1.9-2.0) to 45.2% (95% CI 44.9-45.6). Following the 2013 Diabetes Canada guideline change, one-step screening decreased to 42.8% (95% CI 42.5-43.1). Of those receiving one-step screening, 18% were diagnosed with GDM compared to 9% with two-step screening. Use of one-step screening was higher in pregnant people with risk factors and in larger urban centres. CONCLUSION: GDM screening in BC demonstrated higher use of one-step screening among people with risk factors; however, there were strong regional disparities and considerable variation in screening practices over time and across subgroups.

Impact of the COVID-19 pandemic on perinatal care and outcomes in the United States: An interrupted time series analysis.

BACKGROUND: Hospitals quickly adapted perinatal care to mitigate SARS-CoV-2 transmission at the onset of the COVID-19 pandemic. The objective of this study was to estimate the impact of pandemic-related hospital policy changes on perinatal care and outcomes in one region of the United States. METHODS: This interrupted time series analysis used retrospective data from consecutive singleton births at 15 hospitals in the Pacific Northwest from 2017 to 2020. The primary outcomes were those hypothesized to be affected by pandemic-related hospital policies and included labor induction, epidural use, oxytocin augmentation, mode of delivery, and early discharge (<48 hours after cesarean and <24 hours after vaginal births). Secondary outcomes included preterm birth, severe maternal morbidity, low 5-minute Apgar score, neonatal intensive care unit (NICU) admission, and 30-day readmission. Segmented Poisson regression models estimated the outcome level shift changes after the pandemic onset, controlling for underlying trends, seasonality, and stratifying by parity. RESULTS: No statistically significant changes were detected in intrapartum interventions or mode of delivery after onset of the pandemic. Early discharge increased for all births following cesarean and vaginal birth. Newborn readmission rates increased but only among nulliparas (aRR: 1.49, 95%CI: 1.17, 1.91). Among multiparas, decreases were observed in preterm birth (aRR: 0.90, 95%CI: 0.84, 0.96), low 5-minute Apgar score (aRR: 0.75, 95%CI: 0.68, 0.81), and term NICU admission rates (aRR: 0.85, 95%CI: 0.80, 0.91). CONCLUSIONS: Increases in early discharge and newborn readmission rates among nulliparas suggest a need for more postpartum support during the pandemic. Decreases in preterm birth and term NICU admission among multiparas may have implications beyond the pandemic and deserve further study.

Birth Outcomes for Planned Home and Licensed Freestanding Birth Center Births in Washington State.

OBJECTIVE: To describe rates of maternal and perinatal birth outcomes for community births and to compare outcomes by planned place of birth (home vs state-licensed, freestanding birth center) in a Washington State birth cohort, where midwifery practice and integration mirrors international settings. METHODS: We conducted a retrospective cohort study including all births attended by members of a statewide midwifery professional association that were within professional association guidelines and met eligibility criteria for planned birth center birth (term gestation, singleton, vertex fetus with no known fluid abnormalities at term, no prior cesarean birth, no hypertensive disorders, no prepregnancy diabetes), from January 1, 2015 through June 30, 2020. Outcome rates were calculated for all planned community births in the cohort. Estimated relative risks were calculated comparing delivery and perinatal outcomes for planned births at home to state-licensed birth centers, adjusted for parity and other confounders. RESULTS: The study population included 10,609 births: 40.9% planned home and 59.1% planned birth center births. Intrapartum transfers to hospital were more frequent among nulliparous individuals (30.5%; 95% CI 29.2-31.9) than multiparous individuals (4.2%; 95% CI 3.6-4.6). The cesarean delivery rate was 11.4% (95% CI 10.2-12.3) in nulliparous individuals and 0.87% (95% CI 0.7-1.1) in multiparous individuals. The perinatal mortality rate after the onset of labor (intrapartum and neonatal deaths through 7 days) was 0.57 (95% CI 0.19-1.04) per 1,000 births. Rates for other adverse outcomes were also low. Compared with planned birth center births, planned home births had similar risks in crude and adjusted analyses. CONCLUSION: Rates of adverse outcomes for this cohort in a U.S. state with well-established and integrated community midwifery were low overall. Birth outcomes were similar for births planned at home or at a state-licensed, freestanding birth center.

Household income and contraceptive methods among female youth: a cross-sectional study using the Canadian Community Health Survey (2009-2010 and 2013-2014).

BACKGROUND: Low socioeconomic status is one of many barriers that may limit access to family planning services. We aimed to examine the relation between household income and contraceptive methods among female youth in Canada. METHODS: Our study population included sexually active females aged 15-24 who were trying to avoid pregnancy. We used cross-sectional data from the 2009-2010 and 2013-2014 cycles of the Canadian Community Health Survey to compare household income and other sociodemographic covariates for those using oral contraceptives, injectable contraceptives, condoms or a dual method (condoms plus oral or injectable contraceptives). RESULTS: Of female youth at risk for unintended pregnancy, 59.2% reported using oral contraceptives, 29.0% used dual methods, 16.8% used condoms only, 2.5% used injectable contraceptives and 13.6% did not use contraception. In multiple regression models, lower annual household income (< $80 000) was associated with decreased use of oral contraceptives (relative risk [RR] 0.85, 95% confidence interval [CI] 0.80-0.91) and dual methods (RR 0.81, 95% CI 0.71-0.91), increased use of condoms (RR 1.36, 95% CI 1.11-1.67) and injectable contraceptives (RR 1.69, 95% CI 0.98-2.92), and a greater risk of contraceptive nonuse (RR 1.19, 95% CI 0.94-1.50). INTERPRETATION: We found that lower household income was associated with decreased use of oral contraceptives and increased reliance on injectable contraceptives and condoms only. Young, low-income females may face barriers to accessing the full range of contraceptive methods available in Canada. Easier access to affordable contraception may decrease the number of female youth at risk for unintended pregnancy due to financial barriers.

Comparison of Midwifery and Obstetric Care in Low-Risk Hospital Births.

OBJECTIVE: To compare midwife and obstetrician labor practices and birth outcomes in women with low-risk pregnancies delivered in the hospital. METHODS: We conducted a retrospective cohort study of singleton births of 37 0/7-42 6/7 weeks of gestation at 11 hospitals between January 1, 2014, and December 31, 2018. Exclusions included intrapartum transfer from home-birth center, antepartum stillbirth, previous cesarean delivery, practitioner other than midwife or obstetrician, prelabor cesarean, prepregnancy maternal disease, and pregnancy complications or risk factors. Interventions (induction, artificial rupture of membranes, epidural, oxytocin, and episiotomy), mode of delivery, maternal outcomes (third- or fourth-degree laceration, postpartum hemorrhage, blood transfusion, and severe maternal morbidity), and newborn outcomes (shoulder dystocia, 5-minute Apgar score less than 7, resuscitation at delivery, birth trauma, and neonatal intensive care unit admission) were examined by practitioner type. We used modified Poisson regression models adjusted for individual confounders to assess risk ratios, stratified by parity, for health care provider type and perinatal outcomes. RESULTS: The study cohort comprised 23,100 births (3,816 midwife and 19,284 obstetrician). Compared with obstetricians, midwifery patients had significantly lower intervention rates, an approximately 30% lower risk of cesarean delivery in nulliparous patients (adjusted relative risk [aRR] 0.68; 95th% CI 0.57-0.82), and an approximately 40% lower risk of cesarean in multiparous patients (aRR 0.57; 95th% CI 0.36-0.89). Operative vaginal birth was also less common in nulliparous patients (aRR 0.73; 95th% CI 0.57-0.93) and multiparous patients (aRR 0.30; 95th% CI 0.14-0.63). Shoulder dystocia was more common in multiparous patients receiving midwifery care (aRR 1.42; 95th% CI 1.04-1.92). CONCLUSIONS: In low-risk pregnancies, midwifery care in labor was associated with decreased intervention, decreased cesarean and operative vaginal births, and, in multiparous women, an increased risk for shoulder dystocia. Greater integration of midwifery care into maternity services in the United States may reduce intervention in labor and potentially even cesarean delivery, in low-risk pregnancies. Larger research studies are needed to evaluate uncommon but important maternal and newborn outcomes.

The Giving Voice to Mothers study: inequity and mistreatment during pregnancy and childbirth in the United States.

BACKGROUND: Recently WHO researchers described seven dimensions of mistreatment in maternity care that have adverse impacts on quality and safety. Applying the WHO framework for quality care, service users partnered with NGOs, clinicians, and researchers, to design and conduct the Giving Voice to Mothers (GVtM)-US study. METHODS: Our multi-stakeholder team distributed an online cross-sectional survey to capture lived experiences of maternity care in diverse populations. Patient-designed items included indicators of verbal and physical abuse, autonomy, discrimination, failure to meet professional standards of care, poor rapport with providers, and poor conditions in the health system. We quantified the prevalence of mistreatment by race, socio-demographics, mode of birth, place of birth, and context of care, and describe the intersectional relationships between these variables. RESULTS: Of eligible participants (n = 2700), 2138 completed all sections of the survey. One in six women (17.3%) reported experiencing one or more types of mistreatment such as: loss of autonomy; being shouted at, scolded, or threatened; and being ignored, refused, or receiving no response to requests for help. Context of care (e.g. mode of birth; transfer; difference of opinion) correlated with increased reports of mistreatment. Experiences of mistreatment differed significantly by place of birth: 5.1% of women who gave birth at home versus 28.1% of women who gave birth at the hospital. Factors associated with a lower likelihood of mistreatment included having a vaginal birth, a community birth, a midwife, and being white, multiparous, and older than 30 years. Rates of mistreatment for women of colour were consistently higher even when examining interactions between race and other maternal characteristics. For example, 27.2% of women of colour with low SES reported any mistreatment versus 18.7% of white women with low SES. Regardless of maternal race, having a partner who was Black also increased reported mistreatment. CONCLUSION: This is the first study to use indicators developed by service users to describe mistreatment in childbirth in the US. Our findings suggest that mistreatment is experienced more frequently by women of colour, when birth occurs in hospitals, and among those with social, economic or health challenges. Mistreatment is exacerbated by unexpected obstetric interventions, and by patient-provider disagreements.

What does sleep hygiene have to offer children's sleep problems?

Sleep hygiene practices have been described extensively in the literature. There is considerably less clarity about relationships between particular elements of sleep hygiene and particular sleep outcomes, and which intervention approaches using sleep hygiene principles are effective. In this review, we describe themes extracted from a systematic review of the sleep hygiene literature. We systematically searched Psycinfo, CINAHL, Cochrane, Ovid Medline, Embase, and Web of Science Search Engines up to August, 2017. We included all studies that associated sleep hygiene (behaviors adjacent to bedtime and during the night) with sleep duration and/or sleep onset latency and/or night waking or that used sleep-hygiene based interventions to improve sleep duration and/or sleep onset latency and/or night waking (n = 44). We organized our findings into themes by age group, sleep hygiene factors, and interventions. We provide evidence-based recommendations about areas of sleep hygiene that have significant empirical support and those that require urgent attention.

A systematic review of nonpharmacological prenatal interventions for pregnancy-specific anxiety and fear of childbirth.

BACKGROUND: Despite a sharp increase in the number of publications that report on treatment options for pregnancy-specific anxiety and fear of childbirth (PSA/FoB), no systematic review of nonpharmacological prenatal interventions for PSA/FoB has been published. Our team addressed this gap, as an important first step in developing guidelines and recommendations for the treatment of women with PSA/FoB. METHODS: Two databases (PubMed and Mendeley) were searched, using a combination of 42 search terms. After removing duplicates, two authors independently assessed 208 abstracts. Sixteen studies met eligibility criteria, ie, the article reported on an intervention, educational component, or treatment regime for PSA/FoB during pregnancy, and included a control group. Independent quality assessments resulted in the retention of seven studies. RESULTS: Six of seven included studies were randomized controlled trials (RCTs) and one a quasi-experimental study. Five studies received moderate quality ratings and two strong ratings. Five of seven studies reported significant changes in PSA/FoB, as a result of the intervention. Short individual psychotherapeutic interventions (1.5-5 hours) delivered by midwives or obstetricians were effective for women with elevated childbirth fear. Interventions that were effective for pregnant women with a range of different fear/anxiety levels were childbirth education at the hospital (2 hours), prenatal Hatha yoga (8 weeks), and an 8-week prenatal education course (16 hours). CONCLUSIONS: Findings from this review can inform the development of treatment approaches to support pregnant women with PSA/FoB.

Rural community birth: Maternal and neonatal outcomes for planned community births among rural women in the United States, 2004-2009.

BACKGROUND: Approximately 22% of women in the United States live in rural areas with limited access to obstetric care. Despite declines in hospital-based obstetric services in many rural communities, midwifery care at home and in free standing birth centers is available in many rural communities. This study examines maternal and neonatal outcomes among planned home and birth center births attended by midwives, comparing outcomes for rural and nonrural women. METHODS: Using the Midwives Alliance of North America Statistics Project 2.0 dataset of 18 723 low-risk, planned home, and birth center births, rural women (n = 3737) were compared to nonrural women. Maternal outcomes included mode of delivery (cesarean and instrumental delivery), blood transfusions, severe events, perineal lacerations, or transfer to hospital and a composite (any of the above). The primary neonatal outcome was a composite of early neonatal intensive care unit or hospital admissions (longer than 1 day), and intrapartum or neonatal deaths. Analysis involved multivariable logistic regression, controlling for sociodemographics, antepartum, and intrapartum risk factors. RESULTS: Rural women had different risk profiles relative to nonrural women and reduced risk of adverse maternal and neonatal outcomes in bivariable analyses. However, after adjusting for risk factors and confounders, there were no significant differences for a composite of maternal (adjusted odds ratio [aOR] 1.05 [95% confidence interval {CI} 0.93-1.19]) or neonatal (aOR 1.13 [95% CI 0.87-1.46]) outcomes between rural and nonrural pregnancies. CONCLUSION: Among this sample of low-risk women who planned midwife-led community births, no increased risk was detected by rural vs nonrural status.

Using Global Positioning Systems (GPS) and temperature data to generate time-activity classifications for estimating personal exposure in air monitoring studies: an automated method.

BACKGROUND: Personal exposure studies of air pollution generally use self-reported diaries to capture individuals' time-activity data. Enhancements in the accuracy, size, memory and battery life of personal Global Positioning Systems (GPS) units have allowed for higher resolution tracking of study participants' locations. Improved time-activity classifications combined with personal continuous air pollution sampling can improve assessments of location-related air pollution exposures for health studies. METHODS: Data was collected using a GPS and personal temperature from 54 children with asthma living in Montreal, Canada, who participated in a 10-day personal air pollution exposure study. A method was developed that incorporated personal temperature data and then matched a participant's position against available spatial data (i.e., road networks) to generate time-activity categories. The diary-based and GPS-generated time-activity categories were compared and combined with continuous personal PM2.5 data to assess the impact of exposure misclassification when using diary-based methods. RESULTS: There was good agreement between the automated method and the diary method; however, the automated method (means: outdoors = 5.1%, indoors other =9.8%) estimated less time spent in some locations compared to the diary method (outdoors = 6.7%, indoors other = 14.4%). Agreement statistics (AC1 = 0.778) suggest 'good' agreement between methods over all location categories. However, location categories (Outdoors and Transit) where less time is spent show greater disagreement: e.g., mean time "Indoors Other" using the time-activity diary was 14.4% compared to 9.8% using the automated method. While mean daily time "In Transit" was relatively consistent between the methods, the mean daily exposure to PM2.5 while "In Transit" was 15.9 µg/m3 using the automated method compared to 6.8 µg/m3 using the daily diary. CONCLUSIONS: Mean times spent in different locations as categorized by a GPS-based method were comparable to those from a time-activity diary, but there were differences in estimates of exposure to PM2.5 from the two methods. An automated GPS-based time-activity method will reduce participant burden, potentially providing more accurate and unbiased assessments of location. Combined with continuous air measurements, the higher resolution GPS data could present a different and more accurate picture of personal exposures to air pollution.

Development of temporally refined land-use regression models predicting daily household-level air pollution in a panel study of lung function among asthmatic children.

Regulatory monitoring data and land-use regression (LUR) models have been widely used for estimating individual exposure to ambient air pollution in epidemiologic studies. However, LUR models lack fine-scale temporal resolution for predicting acute exposure and regulatory monitoring provides daily concentrations, but fails to capture spatial variability within urban areas. This study coupled LUR models with continuous regulatory monitoring to predict daily ambient nitrogen dioxide (NO(2)) and particulate matter (PM(2.5)) at 50 homes in Windsor, Ontario. We compared predicted versus measured daily outdoor concentrations for 5 days in winter and 5 days in summer at each home. We also examined the implications of using modeled versus measured daily pollutant concentrations to predict daily lung function among asthmatic children living in those homes. Mixed effect analysis suggested that temporally refined LUR models explained a greater proportion of the spatial and temporal variance in daily household-level outdoor NO(2) measurements compared with daily concentrations based on regulatory monitoring. Temporally refined LUR models captured 40% (summer) and 10% (winter) more of the spatial variance compared with regulatory monitoring data. Ambient PM(2.5) showed little spatial variation; therefore, daily PM(2.5) models were similar to regulatory monitoring data in the proportion of variance explained. Furthermore, effect estimates for forced expiratory volume in 1 s (FEV(1)) and peak expiratory flow (PEF) based on modeled pollutant concentrations were consistent with effects based on household-level measurements for NO(2) and PM(2.5). These results suggest that LUR modeling can be combined with continuous regulatory monitoring data to predict daily household-level exposure to ambient air pollution. Temporally refined LUR models provided a modest improvement in estimating daily household-level NO(2) compared with regulatory monitoring data alone, suggesting that this approach could potentially improve exposure estimation for spatially heterogeneous pollutants. These findings have important implications for epidemiologic studies - in particular, for research focused on short-term exposure and health effects.

Urinary polycyclic aromatic hydrocarbons as a biomarker of exposure to PAHs in air: a pilot study among pregnant women.

Recent studies have linked increased polycyclic aromatic hydrocarbons (PAHs) in air and adverse fetal health outcomes. Urinary PAH metabolites are of interest for exposure assessment if they can predict PAHs in air. We investigated exposure to PAHs by collecting air and urine samples among pregnant women pre-selected as living in "high" (downtown and close to steel mills, n=9) and "low" (suburban, n=10) exposure areas. We analyzed first-morning urine voids from all 3 trimesters of pregnancy for urinary PAH metabolites and compared these to personal air PAH/PM(2.5)/NO(2)/NO(X) samples collected in the 3rd trimester. We also evaluated activities and home characteristics, geographic indicators and outdoor central site PM(2.5)/NO(2)/NO(X) (all trimesters). Personal air exposures to the lighter molecular weight (MW) PAHs were linked to indoor sources (candles and incense), whereas the heavier PAHs were related to outdoor sources. Geometric means of all personal air measurements were higher in the "high" exposure group. We suggest that centrally monitored heavier MW PAHs could be used to predict personal exposures for heavier PAHs only. Urine metabolites were only directly correlated with their parent air PAHs for phenanthrene (Pearson's r=0.31-0.45) and fluorene (r=0.37-0.58). Predictive models suggest that specific metabolites (3-hydroyxyfluorene and 3-hydroxyphenanthrene) may be related to their parent air PAH exposures. The metabolite 2-hydroxynaphthalene was linked to smoking and the metabolite 1-hydroxypyrene was linked to dietary exposures. For researchers interested in predicting exposure to airborne lighter MW PAHs using urinary PAH metabolites, we propose that hydroxyfluorene and hydroxyphenanthrene metabolites be considered.

Time-activity patterns of pregnant women and changes during the course of pregnancy.

Numerous studies suggest that in utero exposures to environmental contaminants are associated with fetal development, congenital anomalies, learning difficulties or other health impacts later in life. Although location and time-activity data have been used to model exposure to specific contaminants in epidemiological studies, little information is available about time-activity patterns of pregnant women. We measured changes in location-based activity patterns over the course of pregnancy (48-h periods, during two or three trimesters) using a self-reported time-activity log among a nonrandom sample of pregnant women (n=62). We assessed the influence of demographics and personal factors on changes in activity over pregnancy using mixed effects regression models. Increasing weeks of pregnancy was a significant predictor for increased time spent at home (1 h/day increase for each trimester of pregnancy), after adjusting for income (2.6 more h/day at home in lowest income group), work status (3.5 more h/day at home for nonworkers) and other children in the family (1.5 more h/day at home with other children). No other measured activities (time outdoors, time in transit modalities or time in other indoor locations) were related to weeks of pregnancy. As our results indicate that pregnant women tend to spend more time at home during the latter stages of pregnancy, future exposure and epidemiological research should consider the potential increase in home-based exposures (i.e., indoor air pollution or chemicals in the home) late in pregnancy, and increased confidence in exposure proxies based on home locations or characteristics during the same period.

The influence of living near roadways on spirometry and exhaled nitric oxide in elementary schoolchildren.

BACKGROUND: Living near major roadways has been associated with an increase in respiratory symptoms, but little is known about how this relates to airway inflammation. OBJECTIVE: We assessed the effects of living near local residential roadways based on objective indicators of ventilatory function and airway inflammation. METHODS: We estimated ambient air pollution, resolved to the level of the child's neighborhood, using a land-use regression model for children 9-11 years of age. We also summed the length of roadways found within a 200-m radius of each child's neighborhood. We had measurements of both air pollution exposure and spirometry for 2,328 children, and also had measurements of exhaled nitric oxide (eNO) for 1,613 of these children. RESULTS: Each kilometer of local roadway within a 200-m radius of the home was associated with a 6.8% increase in eNO (p = 0.045). Each kilometer of any type of roadway (local, major, highway) was also associated with an increase in eNO of 10.1% (p = 0.002). Each microgram per cubic meter increase in PM2.5 was associated with a 3.9% increase in eNO (p = 0.058) and 0.70% decrease in forced vital capacity (FVC) expressed as a percentage of predicted (p = 0.39). Associations between roadway density and both forced expired volume in 1 sec and FVC were negative but not statistically significant at p < 0.05. CONCLUSION: Traffic from local neighborhood roadways may cause airway inflammation as indicated by eNO. This may be a more sensitive indicator of adverse air pollution effects than traditional measures of ventilatory function.