The success of Conditional Cash Transfer (CCTs) program in several health and social domains has led to recent experiments testing CCTs for sexual and reproductive health. However, this approach has yielded mixed results and has been understudied. My dissertation explores whether sexual relationship power - the power women have to decide if and when to have sex, with whom, and with or without a condom - influences the effectiveness of CCTs to reduce STIs, and additionally, if these CCTs influence relationship power. If we can answer these questions, researchers will be better able to design CCT interventions to reduce the spread of STIs and HIV.

My overall hypotheses are: (1) CCTs given to women with high baseline relationship power are more effective at reducing STIs than CCTs given to women with low baseline relationship power (Chapter 1); and (2) that the CCT itself changes the relationship power of those enrolled in the intervention (Chapter 2). A relevant example of women’s power to negotiate safer sex is female sex workers’ interactions with their clients. Therefore, in chapter 3, I draw on theoretical models and previous literature related to the determinants of safer sex among commercial sex workers to analyze qualitatively how Female Sex Workers (FSWs) respond to a novel pilot study using CCTs to incentivize safe sex (Chapter 3).

To test these hypotheses, I conducted three studies: The first explores the effect modification of baseline relationship power on the impact of CCTs to reduce STIs; the second is an intent-to-treat analysis of the effect of the CCT on relationship power; and the third is a qualitative analysis of how female sex workers respond to a pilot CCT intervention to incentivize safe sex. Chapters 1 and 2 draw on data from the RESPECT study in Tanzania and Chapter 3 draws on data from the RESPECT II Pilot study to reduce STIs and HIV among female sex workers in Tanzania.

My analysis reveals that women’s relationship power significantly modifies the effect of the CCT on STIs. In addition, I show that a CCT improved women’s relationship power, but whether or not women were eligible to receive a high, low, or no cash transfer had little relative impact on changes in their relationship power. Finally, I identify the salient domains of power for female sex workers that are necessary to meet the conditions of a CCT intervention.

Taken together, acknowledging and addressing both the degrees of relationship power and domains of relationship power that women experience when enrolled in a CCT will improve the outcomes of these interventions in the context of STIs and HIV.

Globally over 249 million children in low- and middle-income countries (LMICs) are at risk of not meeting developmental milestones on the motor, cognitive, language or socio-emotional domains. This compromised development may result in less educational attainment and lower economic earnings later in life. The nurturing care framework, developed by the World Health Organization, summarizes the inputs required to promote healthy child development. These inputs include good health, nutrition, responsive caregiving, access to early learning, and safety and security. In pursuit of improved child development, caregiver support interventions have been developed and implemented in numerous LMICs, and have succeeded at improving child language and cognitive development. Most of these interventions, however, were designed to be implemented on a small scale and focus primarily on access to early learning and responsive caregiving.

This dissertation aims to inform the design and evaluation of large-scale interventions to improve child development over the life-course in low-resource settings. In Chapter 1, I evaluate the effects of a multicomponent intervention, that covers early learning, responsive caregiving nutrition, water, sanitation, hygiene, caregiver mental health and lead exposure prevention on child development and risk factors for poor child development. I use data from a cluster randomized controlled trial of an intervention that was delivered primarily in groups in Kishoreganj, Bangladesh. This research contributes to existing literature on the effects on caregiver support interventions on early child development and expands the scope of these interventions to include additional components that may result in larger and more sustained impacts on child outcomes. In Chapter 2, I assess the concurrent correlation between two measures of child development: (i) the Bangladeshi-adapted Ages and Stages Questionnaire: Inventory and (ii) the Bayley Scales of Infant Development-III. The Ages and Stages Questionnaire: Inventory is primarily a caregiver report measure that is feasible to implement to evaluate intervention effects when financial, human, and time resources are constrained, as may be the case with large-scale evaluations. The Bayley Scales of Infant Development-III is a direct assessment measure for child development that has been adapted for use in Bangladesh, and is considered to be less biased than caregiver report in evaluating the effects of early child development interventions. I use endline data from the same cluster randomized trial used in Chapter 1 to examine correlations overall, by age, and by intervention status. This work illustrates the potential of the Bangladeshi-adapted Ages and Stages Questionnaire: Inventory for use in the evaluation of large-scale child development interventions. Finally, in Chapter 3, I describe how the distribution of risk factors for poor child development shifted in response to experiences during the COVID-19 pandemic in Chatmohar, Bangladesh. I analyze data from the evaluation of a large-scale multicomponent child development intervention in Chatmohar, Bangladesh. This analysis highlights the shift of intervention targets for improving population-level early child development in the context of the COVID-19 pandemic. Taken together, this dissertation contributes to the evidence for the design and measurement of effective and scalable interventions to improve child development in LMICs.

Breastfeeding is unmatched in its health benefits for mothers and babies. Breastfeeding is not only a mode of nutrition but also a public health and women’s rights issue. The second half of the twentieth century was a historically unprecedented time for women in the United States. Women began entering the workforce in large numbers, and this surge in labor force participation created complications for breastfeeding. Prolonged physical separation between a mother and baby, lack of adequate space or time to pump breastmilk at work, short maternity leaves, unpaid leave, punitive employers, and rigid work schedules are among the many reasons why returning to work after childbirth is one of the leading factors for early breastfeeding cessation among women in the United States.

Maternity leave is a form of breastfeeding promotion and protection. Paid time away from work after giving birth avoids the multitude of logistical challenges required to maintain breastfeeding while at work and allows women to not have to decide between economic hardship and time off from work. Every single country from the Organization for Economic Cooperation and Development (OECD) mandates paid maternity leave after childbirth except for the United States. The lack of paid maternity leave in the United States forces many women to return to work shortly after childbirth to avoid financial hardship, which has an exceptionally negative impact on breastfeeding outcomes.

On March 19, 2020, Governor Gavin Newson issued a statewide stay-at-home order to reduce the spread of COVID-19, which made California the first state to mandate a community mitigation strategy against COVID-19. Subsequent legislation followed across the country, and each state experienced a reduction in overall mobility with fewer visits to public transit centers, schools, and workplaces. For the first time since women largely entered the workforce in the early 1960s, employed women in the United States were not required to return to work in-person shortly after childbirth. By the end of April 2020, more than 300 million Americans were urged to stay home. These conditions created an opportunity to investigate the impact of extended time away from the workplace on breastfeeding outcomes among women who have been systemically denied a national maternity leave policy.

Paper one is a literature review that explores the intersections between maternity leave length, paid maternity leave, workplace flexibility, and breastfeeding outcomes among employed women in the United States. This paper is guided by three objectives: 1) summarize existing research on the associations between maternity leave length, paid maternity leave, and breastfeeding rates, 2) review the associations between reduced and flexible workhours and breastfeeding outcomes, and 3) highlight where research is needed for improving maternity leave and employment policies to support and sustain breastfeeding. We found strong evidence of a negative relationship between shorter maternity leave length (<12 weeks) and breastfeeding outcomes, moderate evidence of a positive relationship between paid maternity leave and breastfeeding outcomes, and strong evidence that reduced work hours and schedule flexibility improve breastfeeding outcomes. Key actions are needed to support legislation and workplace policies for extended maternity leave, paid maternity leave, and reduced and flexible work hours to increase breastfeeding rates for employed mothers.

Paper two uses 2020-2021 PRAMS data (Pregnancy Risk Assessment and Monitoring System) to examine the associations between having experienced a loss of a job or reduction in work hours or pay due to the COVID-19 pandemic and breastfeeding outcomes for births that occurred in 2020. In our study of 10,192 recently postpartum women, we found that women who did not experience job loss or decreased work hours or pay due to the pandemic were less likely to ever breastfeed and continue breastfeeding at 1 and 2 months than women who had lost a job or experienced a decrease in work hours or pay. Not experiencing job or pay changes due to the pandemic was associated with a lower prevalence of breastfeeding at three months among women who were not married and a lower prevalence of breastfeeding at one and two months among women with lower education levels. Significant interactions were found for women who were not married and had lower education levels, suggesting that an increase in autonomy after job or pay loss may have improved breastfeeding for vulnerable groups of women. Our findings suggest that a flexible schedule is critical for sustaining breastfeeding and more flexibility in work schedules and time off from work after childbirth may improve breastfeeding initiation and duration in the United States, particularly for women with social or education disadvantages.

Paper three uses 2020-2021 PRAMS data to examine the associations between maternity leave length and type with breastfeeding initiation and breastfeeding duration at 1, 2, and 3 months after delivery, and to describe how the findings compare to data collected prior to the COVID-19 pandemic. In our study of 3,683 recently postpartum women who were employed during pregnancy and were newly postpartum in 2020 during the COVID-19 pandemic, maternity leave length was not associated with breastfeeding initiation or breastfeeding continuation at 1, 2, or 3 months. Pre-pandemic data shows associations between shorter maternity leave length and a lower prevalence of breastfeeding initiation and duration whereas our data from during the pandemic reveals no associations between leave length and breastfeeding outcomes. Sub-group analyses revealed significant interactions for women who were not married, received no paid leave, had lower education levels, or were younger in age. Our findings suggest that paid maternity leave may have minimized differences in breastfeeding duration between women who took shorter maternity leaves and women who took longer maternity leaves during the pandemic. Furthermore, taking a shorter maternity leave may have increased the likelihood of breastfeeding cessation specifically for women who were not married, less educated, younger, and received no paid leave.

The age-standardized incidence of cardiovascular disease in high-income countries has fallen precipitously from 844 cases per 100,000 in 1990 to 597 in 2019. However, this reduction in average incidence obscures significant disparities in risk by socioeconomic, genetic, biological, and health behavioral factors. To date, most studies of the risk factors for cardiovascular disease attempt to isolate the effect of a single risk factor. This single-exposure focus belies the dynamic interplay between genetics, socioeconomic status, and traditional health and health behavioral factors that ultimately determine an individual’s cardiovascular disease risk. This dissertation explores the ways in which different domains of risk interact to produce heterogeneous, individualized risk of cardiovascular disease.

The second chapter of this dissertation employs Mendelian randomization, an instrumental variable technique that uses random genetic variation as the instrument, to understand the causal effect of adiposity on cardiovascular disease incidence for individuals at different levels of socioeconomic status. Both high adiposity and low socioeconomic status increase cardiovascular disease risk. However, it is unclear whether the risk caused by an increase in adiposity is itself identical for individuals at varying levels of socioeconomic status or if, instead, individuals at lower levels of socioeconomic status face a greater risk from an increase in adiposity than their peers. If such a disparity did exist, it would imply that the risk implications of weight gain may differ by socioeconomic status. In UK Biobank data, we find that differences in risk in these Mendelian randomization models existed only for individuals with versus without a university degree. The differences in cardiovascular disease risk from higher body mass index by educational attainment or income – if they exist - are small in magnitude, though imprecisely estimated. The results for waist-to-hip ratio adjusted for body mass index, a measure of central adiposity, generally showed even smaller differences between socioeconomic groups.

The third chapter of this dissertation explores whether a health behavior related to lower cardiovascular disease risk, physical activity, might ameliorate some of the risk of coronary artery disease caused by an individual’s genetic predisposition. Specifically, I use wrist-worn accelerometer data combined with the most powerful polygenic risk score in the literature to determine how physical activity volume and intensity impact an individual’s risk of coronary artery disease at different levels of genetic risk. If individuals at higher risk benefit more from greater physical activity than their lower risk peers, this could imply that more personalized physical activity standards should be considered for at-risk patients.Physical activity volume and intensity each had significant independent associations with incident coronary artery disease, with physical activity intensity demonstrating the strongest association. However, no interactive effect of physical activity and genetic risk on coronary artery disease risk was found.

Future research should focus both on the impact of individual risk factors on cardiovascular disease risk and - particularly - how different risk factors and domains might contribute and interact to determine an individual’s overall cardiovascular disease risk. With the proliferation of large-scale cohort datasets such as the UK Biobank, the Million Veteran Program, and All of Us, researchers face an unprecedented opportunity to understand how every aspect of a person’s life from their social and built environment to their medical care access, genetic code, and health behaviors interconnect to determine disease risk.

Objectives Poverty reduction interventions through cash transfers and microcredit have had mixed effects on mental health. In this quasi-experimental study, we evaluate the effect of a living wage intervention on depressive symptoms of apparel factory workers in the Dominican Republic.

Setting Two apparel factories in the Dominican Republic.

Participants The final sample consisted of 204 hourly wage workers from the intervention (99) and comparison (105) factories.

Interventions In 2010, an apparel factory began a living wage intervention including a 350% wage increase and significant workplace improvements. The wage increase was plausibly exogenous because workers were not aware of the living wage when applying for jobs and expected to be paid the usual minimum wage. These individuals were compared with workers at a similar local factory paying minimum wage, 15–16 months postintervention.

Primary outcome measures Workers’ depressive symptoms were assessed using the Center for Epidemiologic Studies-Depression Scale (CES-D). Ordinary least squares and Poisson regressions were used to evaluate treatment effect of the intervention, adjusted for covariates.

Results Intervention factory workers had fewer depressive symptoms than comparison factory workers (unadjusted mean CES-D scores: 10.6±9.3 vs 14.7±11.6, p=0.007). These results were sustained when controlling for covariates (β=−5.4, 95% CI −8.5 to −2.3, p=0.001). In adjusted analyses using the standard CES-D clinical cut-off of 16, workers at the intervention factory had a 47% reduced risk of clinically significant levels of depressive symptoms compared with workers at the comparison factory (23% vs 40%).

Conclusions Policymakers have long grappled with how best to improve mental health among populations in low-income and middle-income countries. We find that providing a living wage and workplace improvements to improve income and well-being in a disadvantaged population is associated with reduced depressive symptoms.