Table 1 Modified PICOT chart outlining the framework underlying this systematic review of the literature reporting early pregnancy loss incidence
| Â | Included | Excluded |
|---|---|---|
Population | All recognized pregnancies, defined by either self-report or report to a health care provider or indicated by a pregnancy-related clinical encounter, in OECD-classified high-income settings, representing general pregnant populations. | Pregnancies not recognized by the pregnant person or pregnancies occurring in a setting not classified as high-income by OECD; study populations restricted to assisted reproductive technology settings |
Outcome | Early pregnancy loss, defined as unintended pregnancy loss occurring prior to 20 weeks’ gestation expressed as the number of losses among all pregnancies in the study period, including all types of unintended pregnancy loss occurring before 20 weeks of gestation or only common types of early pregnancy loss (spontaneous, missed, incomplete abortions only) | Induced abortion, stillbirth (intrauterine fetal demise after 20 completed weeks of gestation), and less common subtypes of early pregnancy loss examined separately (hydatidiform mole/molar pregnancy, anembryonic pregnancy, ectopic pregnancy) |
Time | Jan 1, 1990–August 31, 2021 | Before Jan 1, 1990, or after August 31, 2021 |