Carole B. Rudra

Adult Weight Change, Weight Cycling, and Prepregnancy Obesity in Relation to Risk of Preeclampsia

Background: Preeclampsia has been shown to be associated with obesity, with other risk factors for cardiovascular disease, and with subsequent cardiovascular disease itself. However, the possible association with weight gain and weight cycling has not been evaluated. Methods: In this prospective study of a cohort of 1644 pregnant women, we assessed adult weight change, intentional weight cycling, and prepregnancy obesity in relation to preeclampsia risk. Net weight change from age 18 years to the period 3 months before conception was determined for each participant. Weight cycling was defined as intentional weight loss and unintentional regain of at least 15 pounds during periods not related to pregnancy or lactation. We used multivariate regression procedures to calculate risk ratios (RRs) and 95% confidence intervals (CIs). Results: Relative to women with stable weight (gained or lost <2.5 kg) women who gained 5.0–9.9 kg experienced a 2.6-fold increased risk of preeclampsia (95% CI = 1.0–6.7). The corresponding risk ratio (RR) for women who gained ≥10 kg was 5.1 (2.2–12.2). Intentional weight cycling, after controlling for weight at age 18 years, adult weight change, and other risk factors, was not associated with increased risk of preeclampsia (RR = 1.1; CI = 0.6–1.8). RRs increased monotonically with increasing prepregnancy body mass index greater than 19.8 kg/m2. After adjusting for confounders, the RR for prepregnancy overweight women and obese women were 1.7 (0.6–4.9) and 3.4 (1.5–7.6) respectively. Conclusions: These results suggest that adult weight gain and prepregnancy overweight and obesity status are associated with an increased risk of preeclampsia.

Infant exposure to fine particulate matter and traffic and risk of hospitalization for RSV bronchiolitis in a region with lower ambient air pollution

Few studies investigate the impact of air pollution on the leading cause of infant morbidity, acute bronchiolitis. We investigated the influence of PM(2.5) and other metrics of traffic-derived air pollution exposure using a matched case-control dataset derived from 1997 to 2003 birth and infant hospitalization records from the Puget Sound Region, Washington State. Mean daily PM(2.5) exposure for 7, 30, 60 and lifetime days before case bronchiolitis hospitalization date were derived from community monitors. A regional land use regression model of NO(2) was applied to characterize subjects exposure in the month prior to case hospitalization and lifetime average before hospitalization. Subjects residential proximity within 150 m of highways, major roadways, and truck routes was also assigned. We evaluated 2604 (83%) cases and 23,354 (85%) controls with information allowing adjustment for mothers education, mothers smoking during pregnancy, and infant race/ethnicity. Effect estimates derived from conditional logistic regression revealed very modest increased risk and were not statistically significant for any of the exposure metrics in fully adjusted models. Overall, risk estimates were stronger when restricted to bronchiolitis cases attributed to respiratory syncytial virus (RSV) versus unspecified and for longer exposure windows. The adjusted odds ratio (OR(adj)) and 95% confidence interval per 10 mcg/m(3) increase in lifetime PM(2.5) was 1.14, 0.88-1.46 for RSV bronchiolitis hospitalization. This risk was also elevated for infants who resided within 150 m of a highway (OR(adj) 1.17, 0.95-1.44). This study supports a developing hypothesis that there may be a modest increased risk of bronchiolitis attributable to chronic traffic-derived particulate matter exposure particularly for infants born just before or during peak RSV season. Future studies are needed that can investigate threshold effects and capture larger variability in spatial contrasts among populations of infants.

Ambient carbon monoxide and fine particulate matter in relation to preeclampsia and preterm delivery in western Washington State.

Background Preterm delivery and preeclampsia are common adverse pregnancy outcomes that have been inconsistently associated with ambient air pollutant exposures. Objectives We aimed to prospectively examine relations between exposures to ambient carbon monoxide (CO) and fine particulate matter [≤ 2.5 μm in aerodynamic diameter (PM2.5)] and risks of preeclampsia and preterm delivery. Methods We used data from 3,509 western Washington women who delivered infants between 1996 and 2006. We predicted ambient CO and PM2.5 exposures using regression models based on regional air pollutant monitoring data. Models contained predictor terms for year, month, weather, and land use characteristics. We evaluated several exposure windows, including prepregnancy, early pregnancy, the first two trimesters, the last month, and the last 3 months of pregnancy. Outcomes were identified using abstracted maternal medical record data. Covariate information was obtained from maternal interviews. Results Predicted periconceptional CO exposure was significantly associated with preeclampsia after adjustment for maternal characteristics and season of conception [adjusted odds ratio (OR) per 0.1 ppm = 1.07; 95% confidence interval (CI), 1.02–1.13]. However, further adjustment for year of conception essentially nullified the association (adjusted OR = 0.98; 95% CI, 0.91–1.06). Associations between PM2.5 and preeclampsia were nonsignificant and weaker than associations estimated for CO, and neither air pollutant was strongly associated with preterm delivery. Patterns were similar across all exposure windows. Conclusions Because both CO concentrations and preeclampsia incidence declined during the study period, secular changes in another preeclampsia risk factor may explain the association observed here. We saw little evidence of other associations with preeclampsia or preterm delivery in this setting.

A prospective analysis of recreational physical activity and preeclampsia risk.

PURPOSE Although literature suggests that physical activity may reduce preeclampsia risk, most prior studies have relied on retrospective exposure assessment. We aimed to assess prospectively the relation between recreational physical activity before and during pregnancy and risk of preeclampsia. METHODS We used data from a 1996-2003 cohort study of 2241 pregnant western Washington State residents. During structured interviews conducted at 15 wk of gestation, on average, women reported recreational activities during the year before pregnancy and during the previous 7 d. Preeclampsia diagnosis was established for 111 women using medical record data and standard guidelines. RESULTS Recreational activity in the year before pregnancy was nonstatistically significantly associated with reduced preeclampsia risk (adjusted odds ratio [OR] for any vs none 0.55, 95% confidence interval [CI] 0.30-1.02). Any activity during early pregnancy was not strongly associated with preeclampsia risk (adjusted OR = 1.07, 95% CI = 0.67-1.69). Compared with women who reported no recreational activity before or during early pregnancy, risk was nonsignificantly lower among those who were active only before pregnancy (OR = 0.73, 95% CI = 0.30-1.77) and during both periods (OR = 0.76, 95% CI = 0.34-1.73). Those who were active only in early pregnancy had nonsignificantly increased preeclampsia risk (OR = 2.03, 95% CI = 0.71-5.81). CONCLUSION These results corroborate previous case-control studies suggesting that prepregnancy recreational activity reduces preeclampsia risk. The absence of an association with early-pregnancy recreational activity in this cohort may be due to misclassification of usual early-pregnancy activity.

Perceived exertion in physical activity and risk of gestational diabetes mellitus.

Background: Physical activity has been associated with decreased risk of gestational diabetes mellitus. Expanding on 2 previously published analyses of absolute exertion measures (time spent and energy expended), we assessed the relation between perceived exertion during usual prepregnancy recreational physical activity and gestational diabetes. Methods: We analyzed data from a Washington State 1998–2002 case–control study (216 cases, 472 controls) and a 1996–2002 prospective cohort study (897 participants) separately. We used logistic regression models to derive odds ratios (ORs) and 95% confidence intervals (CIs). Results: Among case–control participants, risk of gestational diabetes was markedly lower for women who reported very strenuous to maximal exertion in usual activity during the year before pregnancy versus those who reported negligible or minimal exertion (adjusted OR = 0.19; CI = 0.15–0.50). There was a direct inverse relation between perceived exertion and risk of gestational diabetes. This relation was also evident among the subset of participants who did not meet physical activity guidelines in the year before pregnancy. Similarly, the OR among cohort participants reporting very strenuous to maximal exertion was 0.57 (0.24–1.37) versus those reporting negligible to moderate exertion. Conclusions: These results suggest that risk of gestational diabetes is inversely related to the exertion perceived during recreational physical activity in the year before pregnancy. Perceived exertion may be a valuable addition to behavior and fitness measures in assessing relations between physical activity and pregnancy-related health outcomes.

Pre-pregnancy body mass index and weight gain during pregnancy in relation to preterm delivery subtypes

Background. Associations between preterm delivery (PTD) and pre‐pregnancy body mass index (BMI) and pregnancy weight gain may differ across outcome subtypes. Methods. The authors analyzed data from 2,468 cohort participants in western Washington State, USA (1996–2005) and examined pre‐pregnancy BMI and weight gain rate from pre‐pregnancy to 18–22 weeks’ gestation in relation to spontaneous PTD after preterm labor, spontaneous PTD after preterm premature rupture of membranes (PPROM), and indicated PTD. Results. Each 5kg/m2 BMI increase was associated with indicated PTD (adjusted odds ratio [OR] 1.71, 95% confidence interval [CI] 1.40–2.06). The association weakened somewhat after adjustment for hypertension and diabetes before and/or during pregnancy (5kg/m2 adjusted OR, 1.40; 95% CI, 1.12–1.75). Associations with spontaneous PTD and PPROM were weaker (5kg/m2 adjusted ORs, 0.90 and 1.14, respectively). Weight gain was associated with indicated delivery among women with normal BMI (0.1kg/week adjusted OR, 1.22; 95% CI, 1.02–1.45) but not among overweight or obese women (adjusted OR, 1.02; 95% CI, 0.87–1.20). Weight gain was inversely associated with spontaneous PTD (0.1kg/week adjusted OR, 0.87; 95% CI, 0.77–0.99) and not strongly associated with PPROM (adjusted OR, 1.03; 95% CI, 0.90–1.17). Conclusions. Pre‐pregnancy overweight increases indicated PTD risk independently of hypertension and diabetes. High early pregnancy weight gain increases indicated PTD risk in women with a normal BMI.

Monthly variation in preeclampsia prevalence: Washington state, 1987–2001

Objective. We investigated the extent of monthly variation in preeclampsia prevalence among primiparous women in Washington State who delivered from 1987 through 2001. Methods. We identified all primiparae who gave birth to a singleton live infant during the study period using state birth records linked to hospital inpatient discharge data. We obtained a random sample and excluded women with pre-existing hypertension, renal disease, or diabetes mellitus or missing information on estimated date of conception (EDC) (n = 79 298). We defined preeclampsia (n = 6680) according to maternal birth hospitalization diagnosis codes and birth records. We calculated adjusted prevalence odds ratios (PR) and 95% confidence intervals (95% CI) of preeclampsia in each month of conception, relative to the month of lowest prevalence. Results. The prevalence of preeclampsia among primiparae was lowest among those conceiving in January (7.7%) and peaked among February, April, and July conceptions (8.9%). After adjustment, prevalence was significantly higher among women conceiving in February and April through August (PRs versus January: 1.14–1.19). Conclusions. The prevalence of preeclampsia among primiparous women in Washington peaks among those conceiving in spring and summer. Exposures with similar monthly fluctuations may contribute to the etiology of preeclampsia.

Using smartphones to collect time-activity data for long-term personal-level air pollution exposure assessment.

Because of the spatiotemporal variability of people and air pollutants within cities, it is important to account for a person’s movements over time when estimating personal air pollution exposure. This study aimed to examine the feasibility of using smartphones to collect personal-level time–activity data. Using Skyhook Wireless’s hybrid geolocation module, we developed “Apolux” (Air, Pollution, Exposure), an AndroidTM smartphone application designed to track participants’ location in 5-min intervals for 3 months. From 42 participants, we compared Apolux data with contemporaneous data from two self-reported, 24-h time–activity diaries. About three-fourths of measurements were collected within 5 min of each other (mean=74.14%), and 79% of participants reporting constantly powered-on smartphones (n=38) had a daily average data collection frequency of <10 min. Apolux’s degree of temporal resolution varied across manufacturers, mobile networks, and the time of day that data collection occurred. The discrepancy between diary points and corresponding Apolux data was 342.3 m (Euclidian distance) and varied across mobile networks. This study’s high compliance and feasibility for data collection demonstrates the potential for integrating smartphone-based time–activity data into long-term and large-scale air pollution exposure studies.

iMAP: Indirect measurement of air pollution with cellphones

In this paper, we introduce the cellphone-based indirect sensing problem. While participatory sensing aims at monitoring of a phenomenon by deploying a dense set of sensors carried by individuals, our indirect sensing problem aims at inferring the manifestations of a sparsely monitored phenomenon on the individuals. The main advantage of the indirect sensing method is that, by making use of existing exposure modeling and estimation methods, it provides a more feasible alternative to direct sensing. Collection of time-location logs using the cellphones plays a major role in our indirect sensing method, while direct sensing at the cellphones is unneeded. We focus on the air pollutant exposure estimation problem as an application of the indirect sensing technique and propose a web-based framework, iMAP, for addressing this problem. We also discuss the information quality (IQ) requirements of indirect sensing in the iMAP framework.

Relation of Blood Cadmium, Lead, and Mercury Levels to Biomarkers of Lipid Peroxidation in Premenopausal Women

Exposures to cadmium, lead, and mercury are associated with adverse health effects, including cardiovascular disease, which may be promoted by lipid peroxidation. The authors examined cadmium, lead, and mercury in relation to plasma levels of F(2)-8α isoprostanes (isoprostane), 9-hydroperoxy-10,12-octadecadienoic acid (9-HODE), 13-hydroxy-9,11-octadecadienoic acid (13-HODE), and thiobarbituric acid reactive substances (TBARS) in 252 women from western New York State (2005-2007). Healthy premenopausal women were followed for ≤2 menstrual cycles, with biomarkers of lipid peroxidation being assessed ≤8 times per cycle. Metals were measured at baseline in whole blood. Linear mixed models were used to estimate the association between cadmium, lead, and mercury and lipid peroxidation biomarkers. Median cadmium, lead, and mercury levels were 0.30 μg/L, 0.86 μg/dL, and 1.10 μg/L, respectively. Blood cadmium, lead, and mercury were not associated with increases in isoprostane, TBARS, 9-HODE, or 13-HODE levels. Isoprostane levels decreased 6.80% (95% confidence interval: -10.40, -3.20) per 1% increase in mercury. However, after adjustment for a simulated strong confounding factor, such as precisely measured fish consumption, the observed association was attenuated, suggesting that this unexpected association could be attributable to unmeasured confounding. In this population of healthy premenopausal women with low exposure levels, cadmium, lead, and mercury were not associated with elevated lipid peroxidation biomarkers.