From here to there: changing the way we evaluate equitable coverage of health services

Reducing inequality in health-service coverage is central to universal health coverage, but the evidence base on how to design successful equity-oriented policies is inadequate to inform decision makers and tends to rely on case studies. Further, conventional measures of inequality capture a single timepoint, one service at a time; this obscures how inequity evolves as coverage increases. We reframe equity as a trajectory and ask how it evolves as total coverage rises, comparing systematically across countries and health areas. Using 132 Demographic and Health Surveys from 22 low- and middle-income countries (1990-2023), we estimated coverage at the subnational (admin1) level by wealth quintile for six representative maternal and child health indicators. For each country-indicator pair, we fit a natural cubic spline of the wealthiest-poorest gap against total regional coverage, extracted features describing each curve, and grouped them using hierarchical clustering. This yielded three archetypes: large rollout gaps (mean peak ~58%), modest but persistent inequality (~30%), and minimal inequality that sometimes reversed to favor the poor (~17%). Most trajectories traced an inverted U pattern, widening early, then closing only near 100% regional coverage. How a service is delivered, more than where, drove its path: institutional delivery was the most inequitable (15 of 20 countries with large gaps), whereas one-touch and campaign-delivered services such as bed nets and vaccines rarely produced large gaps and were sometimes pro-poor. Despite this, some countries achieved equity across nearly all services, indicating that proactive governance may be able to overcome structural challenges to achieve equitable outcomes. For policy, these archetypes let programs anticipate which groups will be left behind and when, replace assumed scenarios with empirical ones in impact models, and target investment early to ensure that new services achieve more equitable coverage.