Table 3.
Participants, Exposure, Comparator, and Outcomes (PECO) Statement
| Category | Description |
|---|---|
| Participants | Pregnant women |
| Exposure | Any pregnancy exposure to air pollution and social determinant of health (SDOH) or preexisting condition that occurred prior to the preeclampsia (PE) or gestational hypertension (GH) assessment. |
| 1) “Any pregnancy exposure” is defined as maternal exposure incurred any time in proximity to conception (as defined by authors of the included study) through birth. | |
| 2) “Air pollution” is defined as any indoor or outdoor source of any inhaled airborne particulate matter or ozone, excluding active and passive smoking. | |
| 3) “SDOH” in our study is limited to a set of exposures determined a priori: poverty, race/ethnicity, psychosocial stress, access to nutrition, access to health care; SDOH exposures can be at the community or individual level. | |
| 4) “Pre-existing condition” is a pregnant woman with a health condition such as diabetes, chronic hypertension, obesity/overweight, or asthma. | |
| 5) Exposures “prior to the PE or GH assessment” include direct and proxy measures for this time period, such as trimesters or entire pregnancy. Note that there is uncertainty about the relevant exposure window for the development of PE or GH, but one hypothesis focuses on conception through first trimester as the most relevant period. | |
| Comparator | Pregnant women exposed to lower levels of air pollution than the more highly exposed women. Pregnant women exposed to lower levels of social stressors than the more highly exposed women. Pregnant women compared to nonpregnant women. |
| 1) This definition is intended to include groups defined by PE or GH case-control studies; for instance, comparing the air pollution exposure levels for people with PE or GH versus those without. | |
| 2) We distinguish the comparator for evaluation within a study used here from the comparison group for the policy synthesis (e.g., the non-at-risk population) | |
| Outcome | Any clinical diagnosis or other continuous or dichotomous scale assessment of preeclampsia or gestational hypertension.a |
a
Preeclampsia is generally defined as new hypertension (blood pressure >140/90mm Hg) and proteinuria (≥300mg in 24 hours) at or after 20 weeks’ gestation and affects 2–10 percent of pregnancies and only resolves with delivery. Gestational hypertension is pregnancy-induced hypertension without proteinuria.