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Open Access Publications from the University of California

Scholarly Works (40 results)

  • Thesis
  • Peer Reviewed
UC Berkeley Electronic Theses and Dissertations (2019)

Understanding the etiology of adverse birth outcomes is of critical public health importance. Preterm delivery and small-for-gestational age births are especially problematic because infants with these conditions experience heightened risk for serious morbidities, mortality, and poorer health and economic outcomes over the life course. There is stark patterning by race/ethnicity and socioeconomic position in the prevalence of adverse birth outcomes, but individual-level risk factors have not adequately explained these disparities. Researchers therefore have expanded their focus upstream to potential fundamental causes like neighborhood poverty and structural racism. However, given that these causes do not necessarily map to realistic interventions, researchers have sought to find a middle ground between fundamental and proximal causes, where the links between levels of causation are clearly articulated, to acknowledge the source of the inequities, but to also identify plausible policy or clinical interventions that could reduce disparities in maternal and infant health. This dissertation contributes to this literature by examining the role of community violence in the etiology of adverse pregnancy outcomes and the perpetuation of inequities in reproductive health. Community violence is a social exposure that is associated with neighborhood and individual socioeconomic status, factors that have been linked to adverse birth outcomes around the world. In addition, Black women in the United States are disproportionately likely to experience both community violence and poor pregnancy outcomes; therefore, community violence may be an important factor for understanding disparities in reproductive health outcomes by race/ethnicity. Furthermore, given that violence in a community is often tied to histories of racial/ethnic segregation, economic exclusion, and social marginalization, exposure to community violence may be an important mechanism through which historical patterns of social inequity continue to shape health disparities today. The first chapter of this dissertation provides background on this question and details potential pathways that could connect community violence with pregnancy outcomes. The second chapter addresses how exposure to homicide in one's neighborhood during early pregnancy influences risk of preterm delivery and small-for-gestational-age birth. The third chapter examines whether overall levels of firearm violence in a woman's community impact her risk of pregnancy complications and health behaviors during pregnancy and subsequent preterm birth. This work aims to assess the relationship between these factors, and to explore how they may be operating to produce disparities in preterm birth. The fourth chapter examines the relationship between exposure to fatal police violence during pregnancy on the hazard of early and late preterm delivery, and assesses whether there is effect modification by race/ethnicity. This chapter also addresses the fact that exposure to violence-related stress during pregnancy may be associated with an increased risk of spontaneous or induced abortion, and includes a simulation study to explore how using birth records that exclude these conceptions may affect the findings. The fifth chapter concludes. Overall, this work contributes new evidence about the relationship between community violence and adverse pregnancy outcomes, and improves our understanding of the etiology of inequities in reproductive health.

    Cover page: Community violence and pregnancy: An understudied exposure in the etiology of adverse birth outcomes
    • Article
    • Peer Reviewed
    Berkeley Research Impact Initiative (BRII) (2018)

    Background

    Few studies have explored the relationship between air pollution and fertility. We used a natural experiment in California when coal and oil power plants retired to estimate associations with nearby fertility rates.

    Methods

    We used a difference-in-differences negative binomial model on the incident rate ratio scale to analyze the change in annual fertility rates among California mothers living within 0-5 km and 5-10 km of 8 retired power plants between 2001 and 2011. The difference-in-differences method isolates the portion of the pre- versus post-retirement contrast in the 0-5 km and 5-10 km bins, respectively, that is due to retirement rather than secular trends. We controlled for secular trends with mothers living 10-20 km away. Adjusted models included fixed effects for power plant, proportion Hispanic, Black, high school educated, and aged > 30 years mothers, and neighborhood poverty and educational attainment.

    Results

    Analyses included 58,909 live births. In adjusted models, we estimated that after power plant retirement annual fertility rates per 1000 women aged 15–44 years increased by 8 births within 5 km and 2 births within 5-10 km of power plants, corresponding to incident rate ratios of 1.2 (95% CI: 1.1–1.4) and 1.1 (95% CI: 1.0–1.2), respectively. We implemented a negative exposure control by randomly selecting power plants that did not retire and repeating our analysis with those locations using the retirement dates from original 8 power plants. There was no association, suggesting that statewide temporal trends may not account for results.

    Conclusions

    Fertility rates among nearby populations appeared to increase after coal and oil power plant retirements. Our study design limited the possibility that our findings resulted from temporal trends or changes in population composition. These results require confirmation in other populations, given known methodological limitations of ecologic study designs.

      • Article
      • Peer Reviewed
      UC San Francisco Previously Published Works (2023)
      Synopsis: Fossil fuels contribute to climate change and petrochemicals, both of which increase maternal and child disease. Reducing fossil fuels can reap a double benefit for climate change and improved health.
        Creative Commons 'BY' version 4.0 license
        • Article
        • Peer Reviewed
        UC San Francisco Previously Published Works (2020)

        Background

        Systematic reviews are increasingly prevalent in environmental health due to their ability to synthesize evidence while reducing bias. Different systematic review methods have been developed by the US National Toxicology Program's Office of Health Assessment and Translation (OHAT), the US Environmental Protection Agency's (EPA) Integrated Risk Information System (IRIS), and by the US EPA under the Toxic Substances Control Act (TSCA), including the approach to assess risk of bias (ROB), one of the most vital steps which is used to evaluate internal validity of the studies. Our objective was to compare the performance of three tools (OHAT, IRIS, TSCA) in assessing ROB.

        Methods

        We selected a systematic review on polybrominated diphenyl ethers and intelligence quotient and/or attention deficit hyperactivity disorder because it had been endorsed by the National Academy of Sciences. Two reviewers followed verbatim instructions from the tools and independently applied each tool to assess ROB in 15 studies previously identified. We documented the time to apply each tool and the impact the ROB ratings for each tool had on the final rating of the quality of the overall body of evidence.

        Results

        The time to complete the ROB assessments varied widely (mean = 20, 32, and 40 min per study for the OHAT, IRIS, and TSCA tools, respectively). All studies were rated overall "low" or "uninformative" using IRIS, due to "deficient" or "critically deficient" ratings in one or two domains. Similarly, all studies were rated "unacceptable" using the TSCA tool because of one "unacceptable" rating in a metric related to statistical power. Approximately half of the studies had "low" or "probably low ROB" ratings across all domains with the OHAT and Navigation Guide tools.

        Conclusions

        Tools that use overall ROB or study quality ratings, such as IRIS and TSCA, may reduce the available evidence to assess the harms of environmental exposures by erroneously excluding studies, which leads to inaccurate conclusions about the quality of the body of evidence. We recommend using ROB tools that circumvents these issues, such as OHAT and Navigation Guide.

        Systematic review registration

        This review has not been registered as it is not a systematic review.
          Cover page: Assessing risk of bias in human environmental epidemiology studies using three tools: different conclusions from different tools.
          • Article
          • Peer Reviewed
          UC Berkeley Previously Published Works (2021)
          Restricting to live births can induce bias in studies of pregnancy and developmental outcomes, but whether this live-birth bias results in underestimating disparities is unknown. Bias may arise from collider stratification due to an unmeasured common cause of fetal loss and the outcome of interest, or depletion of susceptibles, where exposure differentially causes fetal loss among those with underlying susceptibility.

          Methods

          We conducted a simulation study to examine the magnitude of live-birth bias in a population parameterized to resemble one year of conceptions in California (N = 625,000). We simulated exposure to a non-time-varying environmental hazard, risk of spontaneous abortion, and time to live birth using 1000 Monte Carlo simulations. Our outcome of interest was preterm birth. We included a social vulnerability factor to represent social disadvantage, and estimated overall risk differences for exposure and preterm birth using linear probability models and stratified by the social vulnerability factor. We calculated how often confidence intervals included the true point estimate (CI coverage probabilities) to illustrate whether effect estimates differed qualitatively from the truth.

          Results

          Depletion of susceptibles resulted in a larger magnitude of bias compared with collider stratification, with larger bias among the socially vulnerable group. Coverage probabilities were not adversely affected by bias due to collider stratification. Depletion of susceptibles reduced coverage, especially among the socially vulnerable (coverage among socially vulnerable = 46%, coverage among nonsocially vulnerable = 91% in the most extreme scenario).

          Conclusions

          In simulations, hazardous environmental exposures induced live-birth bias and the bias was larger for socially vulnerable women.
            Cover page: Environmental hazards, social inequality, and fetal loss: Implications of live-birth bias for estimation of disparities in birth outcomes
            • Article
            • Peer Reviewed
            UC Berkeley Previously Published Works (2019)
            Police use of force is an important public health issue in the US. Recent high-profile incidents suggest a potential link between mental disorders and police use of force, however little research has examined their co-occurrence in the general population. We aimed to assess the overall association between specific mental and substance use disorders (MSUDs) and nonfatal legal intervention injury. We identified nonfatal legal intervention injury cases (n = 90,099) and MSUD diagnoses from all hospital and emergency department (ED) records in California between 2005 and 2014. Age-, sex-, and race-standardized MSUD prevalence estimates among legal intervention injury cases, stratified by inpatient status, were compared to general US population-based estimates from the National Comorbidity Survey Replication. Compared to the general US population, nonaffective psychoses, mood disorders, alcohol use disorders, and drug use disorders were substantially overrepresented among inpatient legal intervention injuries (prevalence difference [PD]: 19.2%, (95% confidence interval [CI]: 18.0, 20.4); PD: 15.3%, (95% CI: 13.9, 16.7); PD: 21.1%, (95% CI: 19.8, 22.4); PD: 29.7%, (95% CI: 28.4, 31.0), respectively). Associations for all except mood disorders were similar but attenuated among ED injury cases. In contrast, anxiety disorders were underrepresented in both inpatient and ED injury cases. Results for mood disorders and suicidal ideation were mixed. In summary, MSUDs characterized by more overt behavioral symptoms were substantially overrepresented among legal intervention injury cases. Findings support the potential importance of interventions to improve treatment and law enforcement recognition of such disorders. Additional research should disentangle the complex relationship between MSUDs and legal intervention injury.
              Cover page: Mental and substance use disorders among legal intervention injury cases in California, 2005–2014
              • Article
              • Peer Reviewed
              UC Berkeley Previously Published Works (2019)

              Background

              Community violence is an understudied aspect of social context that may affect risk of preterm birth and small-for-gestational age (SGA).

              Methods

              We matched California mothers with live singleton births who were exposed to a homicide in their Census tract of residence in 2007-2011 to unexposed mothers within the same tract. We estimated risk differences with a weighted linear probability model, with weights corresponding to the matched data structure. We estimated the average treatment effect on the treated of homicide exposure on the risk of preterm birth and SGA during the preconception period and first and second trimester.

              Results

              We found a small increase in risk of SGA associated with homicide exposure in the first trimester (0.14% [95% confidence interval (CI) = -0.01%, 0.30%]), but not for exposure during the preconception period (-0.01% [95% CI = -0.17%, 0.15%]) or the second trimester (-0.06% [95% CI = -0.23%, 0.11%]). Risk of preterm birth was not affected by homicide exposure. When women were exposed to homicides during all three exposure windows, there was a larger increase in risk of SGA (1.09% [95% CI = 0.15%, 2.03%]) but not preterm birth (0.14% [95% CI = -0.74%, 1.01%]). Exposure to three or more homicides was also associated with greater risk of SGA (0.78% [95% CI = 0.15%, 1.40%]). Negative controls indicated that residual confounding by temporal patterning was unlikely.

              Conclusions

              Homicide exposure during early pregnancy is associated with a small increased risk of SGA.
                Cover page: Exposure to Community Homicide During Pregnancy and Adverse Birth Outcomes: A Within-Community Matched Design.
                • Article
                • Peer Reviewed
                UCSF Open Access Publishing Fund (2020)
                  • Article
                  • Peer Reviewed
                  UC San Francisco Previously Published Works (2020)
                  BACKGROUND: Previous studies have shown a correlation between fluoride concentrations in urine and community water fluoride concentrations. However, there are no studies of the relationship between community water fluoridation, urine, serum, and amniotic fluid fluoride concentrations in pregnant women in the US. The aim of this study was to determine the relationship between maternal urine fluoride (MUF), maternal urine fluoride adjusted for specific gravity (MUFSG), maternal serum fluoride (MSF), amniotic fluid fluoride (AFF) concentrations during pregnancy, and community water fluoridation in Northern California. METHODS: Archived samples of urine, serum and amniotic fluid collected from second trimester pregnant women in Northern California from 47 different communities in Northern California and one from Montana (n = 48), were analyzed for fluoride using an ion specific electrode following acid microdiffusion. Womens addresses were matched to publicly reported water fluoride concentrations. We examined whether fluoride concentrations in biospecimens differed by fluoridation status of the community water, and determined the association between water fluoride concentrations and biospecimen fluoride concentrations using linear regression models adjusted for maternal age, smoking, Body Mass Index (BMI), race/ethnicity, and gestational age at sample collection. RESULTS: Fluoride concentrations in the community water supplies ranged from 0.02 to 1.00 mg/L. MUF, MSF , and AFF concentrations were significantly higher in pregnant women living in communities adhering to the U.S. recommended water fluoride concentration (0.7 mg/L), as compared with communities with less than 0.7 mg/L fluoride in drinking water. When adjusted for maternal age, smoking status, BMI, race/ethnicity, and gestational age at sample collection, a 0.1 mg/L increase in community water fluoride concentration was positively associated with higher concentrations of MUF (B = 0.052, 95% CI:0.019,0.085), MUFSG (B = 0.028, 95% CI: -0.006, 0.062), MSF (B = 0.001, 95% CI: 0.000, 0.003) and AFF (B = 0.001, 95% CI: 0.000, 0.002). CONCLUSIONS: We found universal exposure to fluoride in pregnant women and to the fetus via the amniotic fluid. Fluoride concentrations in urine, serum, and amniotic fluid from women were positively correlated to public records of community water fluoridation. Community water fluoridation remains a major source of fluoride exposure for pregnant women living in Northern California.
                    Cover page: Maternal and fetal exposures to fluoride during mid-gestation among pregnant women in northern California.
                    • Article
                    • Peer Reviewed
                    UC San Francisco Previously Published Works (2022)
                    In the original publication of this article [1], the new reference citation has been included in the body text repeatedly and not added as an endnote.
                      Cover page: Correction: Authors’ rebuttal to Integrated Risk Information System (IRIS) response to “Assessing risk of bias in human environmental epidemiology studies using three tools: different conclusions from different tools”Creative Commons 'BY' version 4.0 license
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