Carrie Nobles

Ambient air pollution and the risk of pregnancy loss: a prospective cohort study

OBJECTIVEnTo estimate the association of pregnancy loss with common air pollutant exposure. Ambient air pollution exposure has been linked to adverse pregnancy outcomes, but few studies have investigated its relationship with pregnancy loss.nnnDESIGNnProspective cohort study.nnnSETTINGnNot applicable.nnnPATIENT(S)nA total of 343 singleton pregnancies in a multisite prospective cohort study with detailed protocols for ovulation and pregnancyxa0testing.nnnINTERVENTION(S)nNone.nnnMAIN OUTCOME MEASURE(S)nTiming of incident pregnancy loss (from ovulation).nnnRESULT(S)nThe incidence of pregnancy loss was 28% (n = 98). Pollutant levels at womens residences were estimated using modified Community Multiscale Air Quality models and averaged during the past 2xa0weeks (acute) and the whole pregnancy (chronic). Adjusted Cox proportional hazards models showed that an interquartile range increase in average whole pregnancy ozone (hazard ratio [HR] 1.12, 95% confidence interval [CI] 1.07-1.17) and particulate matter <2.5xa0μm (HR 1.13, 95% CI 1.03-1.24) concentrations were associated with faster time to pregnancy loss. Sulfate compounds also appeared to increase risk (HR 1.58, 95% CI 1.07-2.34). Last 2xa0weeks of exposuresxa0were not associated with loss.nnnCONCLUSION(S)nIn a prospective cohort of couples trying to conceive, we found evidence that exposure to air pollution throughout pregnancyxa0was associated with loss, but delineating specific periods of heightened vulnerability await larger preconception cohort studies with daily measured air quality.

Time-varying cycle average and daily variation in ambient air pollution and fecundability

STUDY QUESTIONnDoes ambient air pollution affect fecundability?nnnSUMMARY ANSWERnWhile cycle-average air pollution exposure was not associated with fecundability, we observed some associations for acute exposure around ovulation and implantation with fecundability.nnnWHAT IS KNOWN ALREADYnAmbient air pollution exposure has been associated with adverse pregnancy outcomes and decrements in semen quality.nnnSTUDY DESIGN, SIZE, DURATIONnThe LIFE study (2005-2009), a prospective time-to-pregnancy study, enrolled 501 couples who were followed for up to one year of attempting pregnancy.nnnPARTICIPANTS/MATERIALS, SETTING, METHODSnAverage air pollutant exposure was assessed for the menstrual cycle before and during the proliferative phase of each observed cycle (n = 500 couples; n = 2360 cycles) and daily acute exposure was assessed for sensitive windows of each observed cycle (n = 440 couples; n = 1897 cycles). Discrete-time survival analysis modeled the association between fecundability and an interquartile range increase in each pollutant, adjusting for co-pollutants, site, age, race/ethnicity, parity, body mass index, smoking, income and education.nnnMAIN RESULTS AND THE ROLE OF CHANCEnCycle-average air pollutant exposure was not associated with fecundability. In acute models, fecundability was diminished with exposure to ozone the day before ovulation and nitrogen oxides 8 days post ovulation (fecundability odds ratio [FOR] 0.83, 95% confidence interval [CI]: 0.72, 0.96 and FOR 0.84, 95% CI: 0.71, 0.99, respectively). However, particulate matter ≤10 microns 6 days post ovulation was associated with greater fecundability (FOR 1.25, 95% CI: 1.01, 1.54).nnnLIMITATIONS, REASONS FOR CAUTIONnAlthough our study was unlikely to be biased due to confounding, misclassification of air pollution exposure and the moderate study size may have limited our ability to detect an association between ambient air pollution and fecundability.nnnWIDER IMPLICATIONS OF THE FINDINGSnWhile no associations were observed for cycle-average ambient air pollution exposure, consistent with past research in the United States, exposure during critical windows of hormonal variability was associated with prospectively measured couple fecundability, warranting further investigation.nnnSTUDY FUNDING/COMPETING INTEREST(S)nThis work was supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (Longitudinal Investigation of Fertility and the Environment study contract nos. #N01-HD-3-3355, NO1-HD-#-3356, N01-HD-3-3358 and the Air Quality and Reproductive Health Study Contract No. HHSN275200800002I, Task Order No. HHSN27500008). We declare no conflict of interest.

Preconception Blood Pressure Levels and Reproductive Outcomes in a Prospective Cohort of Women Attempting Pregnancy

Elevated blood pressure in young adulthood is an early risk marker for cardiovascular disease. Despite a strong biological rationale, little research has evaluated whether incremental increases in preconception blood pressure have early consequences for reproductive health. We evaluated preconception blood pressure and fecundability, pregnancy loss, and live birth in the EAGeR trial (Effects of Aspirin on Gestational and Reproduction; 2007–2011), a randomized clinical trial of aspirin and reproductive outcomes among 1228 women attempting pregnancy with a history of pregnancy loss. Systolic and diastolic blood pressure were measured during preconception in the first observed menstrual cycle and in early pregnancy and used to derive mean arterial pressure. Fecundability was assessed as number of menstrual cycles until pregnancy, determined through human chorionic gonadotropin testing. Pregnancy loss included both human chorionic gonadotropin–detected and clinical losses. Analyses adjusted for treatment assignment, age, body mass index, race, marital status, smoking, parity, and time since last loss. Mean preconception systolic and diastolic blood pressure were 111.6 mmu2009Hg (SD, 12.1) and 72.5 (SD, 9.4) mmu2009Hg. Risk of pregnancy loss increased 18% per 10 mmu2009Hg increase in diastolic blood pressure (95% confidence interval, 1.03–1.36) and 17% per 10 mmu2009Hg increase in mean arterial pressure (95% confidence interval, 1.02–1.35) in adjusted analyses. Findings were similar for early pregnancy blood pressure. Preconception blood pressure was not related to fecundability or live birth in adjusted analyses. Findings suggest that preconception blood pressure among healthy women is associated with pregnancy loss, and lifestyle interventions targeting blood pressure among young women may favorably impact reproductive health. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00467363.

C-Reactive protein in relation to fecundability and anovulation among eumenorrheic women

OBJECTIVEnTo assess systemic inflammation in relation to fecundability and anovulation.nnnDESIGNnProspective cohort study among participants in the Effects of Aspirin in Gestation and Reproduction trial who were assigned to the placebo.nnnSETTINGnAcademic medical centers.nnnPATIENT(S)nHealthy eumenorrheic women (n = 572), 18-40xa0years of age, with one or two pregnancy losses, attempting spontaneous pregnancy.nnnINTERVENTION(S)nBaseline serum high-sensitivity C-reactive protein (hsCRP) values <10xa0mg/L were categorized into tertiles.nnnMAIN OUTCOME MEASURE(S)nDiscrete Cox proportional hazards models estimated the fecundability odds ratio (FOR) and 95% confidence interval (CI) and adjusted for potential confounders. Log-binomial regression estimated the risk ratio (RR) and 95% CI of anovulation. The algorithm to define anovulation used data on urinary concentrations of hCG, pregnanediol-3-glucuronide, and LH as well as fertility monitor readings.nnnRESULT(S)nHigher hsCRP was associated with reduced fecundability but not with an increased risk of anovulation.nnnCONCLUSION(S)nAmong healthy women attempting pregnancy after one or two pregnancy losses, we found preliminary evidence that systemic inflammation is associated with reduced fecundability, but not independently from adiposity. Sporadic anovulation did not appear to drive this association.nnnCLINICAL TRIAL REGISTRATION NUMBERnClinicalTrials.gov: NCT00467363.

Ambient air pollution and semen quality

Background Ambient air pollution is associated with systemic increases in oxidative stress, to which sperm are particularly sensitive. Although decrements in semen quality represent a key mechanism for impaired fecundability, prior research has not established a clear association between air pollution and semen quality. To address this, we evaluated the association between ambient air pollution and semen quality among men with moderate air pollution exposure. Methods Of 501 couples in the LIFE study, 467 male partners provided one or more semen samples. Average residential exposure to criteria air pollutants and fine particle constituents in the 72 days before ejaculation was estimated using modified Community Multiscale Air Quality models. Generalized estimating equation models estimated the association between air pollutants and semen quality parameters (volume, count, percent hypo‐osmotic swollen, motility, sperm head, morphology and sperm chromatin parameters). Models adjusted for age, body mass index, smoking and season. Results Most associations between air pollutants and semen parameters were small. However, associations were observed for an interquartile increase in fine particulates ≤2.5 &mgr;m and decreased sperm head size, including −0.22 (95% CI −0.34, −0.11) &mgr;m2 for area, −0.06 (95% CI −0.09, −0.03) &mgr;m for length and −0.09 (95% CI −0.19, −0.06) &mgr;m for perimeter. Fine particulates were also associated with 1.03 (95% CI 0.40, 1.66) greater percent sperm head with acrosome. Conclusions Air pollution exposure was not associated with semen quality, except for sperm head parameters. Moderate levels of ambient air pollution may not be a major contributor to semen quality. HighlightsSperm development is sensitive to oxidative stress, a key effect of air pollution.Prior evidence is inconclusive for an effect of air pollution on semen quality.Ambient air pollution was not associated with most semen quality parameters.Fine particulate matter was associated with smaller sperm head measures.Findings are generally reassuring for healthy men exposed to moderate air pollution.

Racial residential segregation and racial disparities in stillbirth in the United States

Abstract We examined whether current and/or persistent racial residential segregation is associated with black‐white stillbirth disparities among 49,969 black and 71,785 white births from the Consortium on Safe Labor (2002–2008). Black‐white segregation was measured using the dissimilarity index and the isolation index, categorized into population‐based tertiles. Using hierarchical logistic models, we found low and decreasing levels of segregation were associated with decreased odds of stillbirth, with blacks benefitting more than whites. Decreasing segregation may prevent approximately 900 stillbirths annually among U.S. blacks. Reducing structural racism, segregation in particular, could help reduce black‐white stillbirth disparities. HighlightsLow and decreasing segregation was associated with decreased risk of stillbirth, with blacks benefitting more than whites.Decreasing segregation may prevent approximately 900 stillbirths annually among blacks.Reducing segregation could potentially reduce persistent racial health disparities.Additional research examining temporal changes in structural racism will advance our understanding of how structural racism is related to persistent racial health disparities.

Air pollution exposure during pregnancy: maternal asthma and neonatal respiratory outcomes

PURPOSEnMaternal asthma increases adverse neonatal respiratory outcomes, and pollution may further increase risk. Air quality in relation to neonatal respiratory health has not been studied.nnnMETHODSnTransient tachypnea of the newborn (TTN), asphyxia, and respiratory distress syndrome (RDS) were identified using medical records among 223,375 singletons from the Consortium on Safe Labor (2002-2008). Community Multiscale Air Quality models estimated pollutant exposures. Multipollutant Poisson regression models calculated adjusted relative risks of outcomes for interquartile range increases in average exposure. Maternal asthma and preterm delivery were evaluated as effect modifiers.nnnRESULTSnTTN risk increased after particulate matter (PM) less than or equal to 10-micron exposure during preconception and trimester one (9-10%), and whole-pregnancy exposure to PM less than or equal to 2.5 microns (PM2.5; 17%) and carbon monoxide (CO; 10%). Asphyxia risk increased after exposure to PM2.5 in trimester one (48%) and whole pregnancy (84%), CO in trimester two and whole pregnancy (28-32%), and consistently for ozone (34%-73%). RDS risk was associated with increased concentrations of nitrogen oxides (33%-42%) and ozone (9%-21%) during all pregnancy windows. Inverse associations were observed with several pollutants, particularly sulfur dioxide. No interaction with maternal asthma was observed. Restriction to term births yielded similar results.nnnCONCLUSIONSnSeveral pollutants appear to increase neonatal respiratory outcome risks.

Ambient temperature and risk of cardiovascular events at labor and delivery: A case-crossover study

Background: Extreme ambient temperatures are linked to cardiac events in the general population, but this relationship is unclear among pregnant women. We estimated the associations and attributable risk between ambient temperature and the risk of cardiovascular event at labor/delivery, and investigated whether these associations vary by maternal race/ethnicity. Methods: We identified 680 women with singleton deliveries affected by cardiovascular events across 12 US sites (2002–2008). Average daily temperature during the week before, delivery day, and each of the seven days before delivery was estimated for each woman. In a case‐crossover analysis, exposures during these hazard periods were compared to two control periods before and after delivery using conditional logistic regression adjusted for other environmental factors. Results: During the cold season (October‐April), 1 °C lower during the week prior to delivery was associated with a 4% (95% CI: 1–7%) increased risk of having a labor/delivery affected by cardiovascular events including cardiac arrest and stroke. During the warm season (May‐September), 1 °C higher during the week prior was associated with a 7% (95% CI: 3–12%) increased risk. These risks translated to 13.4 and 23.9 excess events per 100,000 singleton deliveries during the cold and warm season, respectively. During the warm season, the risks were more pronounced on days closer to delivery and Black women appeared to be more susceptible to the same temperature increase. Conclusion: Small changes in temperature appear to affect the risk of having cardiovascular events at labor/delivery. Black women had a differentially higher warm season risk. These findings merit further investigation. HighlightsLower temperature increased the risk of cardiovascular event in the cold season.Higher temperature was associated with risk during the warm season.In the warm season, risks were more pronounced on days closer to delivery.Black women were more susceptible to higher temperature in the warm season.