Determinants and effects of abortion accessibility in the United States

Abortion, the termination of pregnancy, is safe when provided as a surgical procedure by a trained provider or when the correct dosage of the drugs mifepristone and/or misoprostol are used. Despite this, many barriers to abortion care exist. In the United States (US), targeted state-level abortion restrictions create barriers to care, which make it so that people who wish to utilize abortion care face difficulty or are unable to do so. Such barriers to care have important public health implications, as studies have shown that individuals who cannot access wanted abortion care have poorer psychological, physical, social, and economic outcomes than those who obtained care. This dissertation aims to examine one component of abortion access, accessibility, operationalized as the drive time from a woman’s home to the nearest abortion-providing facility. We employ a novel measure of abortion accessibility constructed from three data sources: (1) the Advancing New Standards in Reproductive Health facility database; (2) US Census estimates and shapefiles; and (3) OpenStreetMap data. In the first study, we used geographic information systems (GIS) to explore the effect of programmatic and policy changes related to telemedicine for medication abortion services (TMAB) on population-level measures of abortion accessibility, or drive time to the nearest abortion-providing facility. We found that either expansions in TMAB services or removal of TMAB bans could improve abortion accessibility in the US. For these two exposure scenarios, compared to the current abortion provision scenario, increases in the proportion of women within a 30-, 60-, and 90-minute drive time of an abortion-providing facility ranged from 1.25 percentage points, or an additional 781,556 US women aged 15-44 years with accessibility, to 5.66 percentage points, or an additional 3,530,423 US women aged 15-44 years with accessibility. In the second study, we used GIS to assess the potential effect of the geographic unit of analysis (i.e., block group, ZIP code tabulation area [ZCTA], or county) on misclassification of the proportion of US women of reproductive age within a 30-minute drive time of an abortion-providing facility relative to a measure calculated using Census blocks. We found that block group- or ZCTA-based estimates of abortion accessibility were an underestimate, but resulted in little misclassification relative to measures constructed using Census blocks at the national level; however, county-based measures substantially underestimated abortion accessibility compared with Census block-based measures. Nationwide, the Census block-based abortion accessibility estimate was 0.35 percentage points greater than the block group-based estimate, 2.72 percentage points greater than the ZCTA-based estimate, and 24.21 percentage points greater than the county-based estimate. By state, the Census block-based abortion accessibility estimate ranged from 0 to 8.51 percentage points greater than the block group-based estimate, from 0 to 27.86 percentage points greater than the ZCTA-based estimate, and from 0 to 79.49 percentage points greater than the county-based estimate. Given that state-level ZCTA-based estimates could be substantially different from the Census block-based estimate, ZCTA-based estimates are likely not appropriate for state-level analyses or US analyses stratified by state. Finally, in the third study, we assessed the relationship between level of accessibility in an abortion client’s home ZCTA and the gestational age at which the client obtained abortion care, using fine stratification by propensity score to control confounding. We found that compared with living in a ZCTA with >0% accessibility, living in a ZCTA with 0% accessibility was associated with a decreased risk of being at or beyond 14 weeks’ gestation at abortion visit. These unexpected findings could be due to a selection bias induced by limiting the sample to those who obtained abortion care, uncontrolled or poorly controlled confounding, misclassification of exposure and/or outcome, and/or unidentified effect measure modification by state abortion provision landscape. Through these three dissertation studies, we highlighted the potential impact on abortion accessibility in the US with different changes in programming and policy, quantified misclassification of abortion accessibility, and examined how misclassification varied by geographic measure and location. The third study in this dissertation suggests a need for more research to identify how selection bias may affect studies of abortion access in the US that rely on data only from those who are able to access care