Widening Socioeconomic Inequalities in Maternal Health Service Utilization in Yemen During Humanitarian Crisis (2013-2022): A Trend Analysis Using Secondary Survey Data

Background Yemen’s protracted humanitarian crisis, ongoing since 2015, has devastated the health system and fundamentally altered access to maternal health services. While overall health coverage has declined across all populations, the burden of this decline has not been evenly distributed. This study examines whether socioeconomic inequalities in maternal health service utilization have widened during Yemen’s humanitarian crisis, and whether these inequalities are attributable to modifiable or structural factors. Methods Secondary analysis of three nationally representative surveys spanning the pre-crisis, early crisis, and mid-crisis periods: Yemen Demographic and Health Survey 2013 (n = 9,265 women aged 15–49); Multiple Indicator Cluster Survey (MICS) 2016 (n = 8,750); and MICS 2022–2023 (n = 7,932). Maternal health indicators included antenatal care (≥ 4 visits with skilled provider), skilled birth attendance, and postnatal care within 48 hours. Socioeconomic inequality was measured using the Erreygers Normalized Concentration Index (ECI)—the WHO-recommended metric—supplemented by absolute differences and relative ratios across wealth quintiles, maternal education, urban-rural residence, and geographic region. Complex survey design was accounted for using stratification and clustering parameters. Bootstrap resampling (10,000 replications) generated 95% confidence intervals. Wagstaff-type decomposition analysis partitioned inequality into contributions from modifiable factors (wealth, education, media exposure, occupation) versus non-modifiable factors (age, parity, region). Results Overall maternal health service coverage declined sharply: antenatal care fell from 64.2% (2013) to 38.1% (2022)—a 26.1 percentage point decline. Skilled birth attendance declined from 52.1% to 24.7%. Postnatal care fell from 38.1% to 15.2%. Critically, socioeconomic inequality—measured by the Erreygers Concentration Index—worsened substantially across all services. The ECI for antenatal care nearly doubled from 0.142 (2013) to 0.289 (2022), p-trend < 0.001, indicating pro-rich concentration. Skilled birth attendance ECI increased from 0.168 to 0.305; postnatal care ECI rose from 0.205 to 0.348. The relative gap between richest and poorest women widened dramatically: for antenatal care, richest women were 1.96 times more likely to receive services in 2013 but 3.80 times more likely by 2022. Rural areas experienced steeper coverage declines than urban areas (50.3% vs. 34.1% for antenatal care; p < 0.001). Education emerged as a powerful stratifier: women with secondary or higher education had 3.37 times higher antenatal care coverage than uneducated women (61.4% vs. 18.2%, 2022). Decomposition analysis revealed that 58.1% of observed wealth-based inequality was attributable to modifiable factors—particularly wealth itself (39.2%), maternal education (12.8%), and media exposure (6.1%)—while 41.9% stemmed from non-modifiable factors. This finding suggests that more than half of observed inequality could theoretically be addressed through targeted, equity-focused interventions. Conclusions Yemen’s humanitarian crisis has created a perfect storm for maternal health inequity. From 2013 to 2022, as overall maternal health service coverage collapsed, the crisis disproportionately harmed the poorest and most vulnerable populations, concentrating services among the wealthy. The Erreygers Concentration Index nearly doubled across all major services, representing one of the sharpest documented increases in health inequality during humanitarian crises. Most significantly, approximately 58% of the observed inequality is driven by modifiable factors, actionable targets for intervention. These findings underscore that maternal health inequity during crisis is not inevitable but rather reflects policy choices regarding resource allocation, service distribution priorities, and equity focus. Without deliberate equity-centered strategies, inequality will continue to widen. With targeted intervention addressing wealth barriers, education gaps, and health system access, worsening inequality can be prevented and potentially reversed, even amid ongoing conflict. The humanitarian response must move beyond vertical programming focused solely on absolute service numbers toward explicitly equity-focused health systems strengthening.