The ability to change behaviors based on past experience is one of the most important and complex functions of the brain. Elucidating how activity of molecules, cells, and circuits all ultimately control learning and memory is difficult, and the simplicity of the nematode C. elegans offers an opportunity to connect these lower-level changes to full-scale changes in behavior. This allows for a depth of understanding of the brain’s biology that is largely impossible in other model organisms. Here we show that the tryptophan metabolite kynurenic acid (KYNA) functions as an inhibitory neuromodulator, communicating information about peripheral physiology to the nervous system to alter behavior. We have found that dietary restriction and many pathways involved in the body’s responses to dietary restriction – long known to affect brain function – enhance learning in C. elegans because they reduce production of KYNA, releasing KYNA-induced inhibition of neuronal activity in a specific pair of interneurons required for learning. In contrast, KYNA production increases with age, accounting for a significant portion of the decline in learning that occurs as animals get older. Furthermore, a C. elegans model of neurodegeneration may also increase KYNA production to impair learning. These studies demonstrate that metabolism can regulate brain function, having profound effects on cellular activity, learning, and memory. They establish that KYNA production is a crucial physiological indicator of peripheral status to the nervous system, offering insight into how the brain integrates information to direct behavior.

The ability of women to safely and effectively control their fertility is a critical health and human rights issue. Family planning provides a range of health, social, and economic benefits for women and their families, yet more than 200 million women worldwide who wish to delay or limit their childbearing are not using any method of contraception. The global health community has recently seen renewed interest in promoting family planning use worldwide. This increased focus on family planning raises questions about how best to deliver reproductive health services to the women who need them, which requires a clearer understanding of how women make decisions about their fertility and how such decisions are carried out.

This dissertation explores the reasons why women's stated fertility intentions do not always align with their fertility behaviors or outcomes. The first paper explores the concept of unmet need for family planning by using both quantitative and qualitative methods to better understand why women who want to prevent a pregnancy choose not to use contraception in Luanda Province, Angola. The second paper considers the social context in which women make decisions about their pregnancies in a post-abortion care context in Zanzibar, Tanzania. The third paper examines how women's experiences in early childhood shape their risk of unintended pregnancy later in life in the United States.

These dissertation papers provide three distinct examples of how researchers' and policy makers' perceptions of women's reproductive decision-making may fail to recognize or address crucial determinants of fertility intentions, behaviors, and outcomes. In particular, they highlight the importance of considering women's fertility decisions within the context of their full reproductive lives, and point to the need for further research to better understand how such decisions shift over the course of women's lives. Policies and programs that can accommodate how these decisions are formed and changed over time are necessary for ensuring that all women have the right to make decisions about their reproduction and to enact these decisions in safe and effective ways.

Background

Methods

Results

Conclusions

The WHO estimates that 13% of maternal mortality is due to unsafe abortion, but challenges with measurement and data quality persist. To our knowledge, no systematic assessment of the validity of studies reporting estimates of abortion-related mortality exists.

Study Design:

To be included in this study, articles had to meet the following criteria: (1) published between September 1^st, 2000-December 1^st, 2011; (2) utilized data from a country where abortion is “considered unsafe”; (3) specified and enumerated causes of maternal death including “abortion”; (4) enumerated ≥100 maternal deaths; (5) a quantitative research study; (6) published in a peer-reviewed journal.

Results :

7,438 articles were initially identified. Thirty-six studies were ultimately included. Overall, studies rated “Very Good” found the highest estimates of abortion related mortality (median 16%, range 1–27.4%). Studies rated “Very Poor” found the lowest overall proportion of abortion related deaths (median: 2%, range 1.3–9.4%).

Conclusions:

Improvements in the quality of data collection would facilitate better understanding global abortion-related mortality. Until improved data exist, better reporting of study procedures and standardization of the definition of abortion and abortion-related mortality should be encouraged