Abstract
BACKGROUND: Within-country inequalities in antenatal care (ANC) coverage are widely documented. With recent international guidelines recommending eight or more visits, we hypothesized that this increase could reveal wider inequalities in Brazil, consistent with the Inverse Equity Hypothesis, which postulates that new interventions initially widen socioeconomic gaps because privileged groups are the first to adopt them. We assess how the magnitude of inequality varies by increasing ANC visit thresholds. METHODS: We analyzed data from the Brazilian Live Births Information System (SINASC) for 2,537,511 live births in 2023, calculating national coverage 1 + to 8 + ANC visits. Estimates were stratified by maternal schooling, self-reported race/skin color, age at birth, and geographic region. Measures of inequality included the Slope Index of Inequality (SII) and the mean absolute difference to the overall mean (MADM). RESULTS: National coverage for 1 + ANC visits was 99.4% and for 8 + visits, 67.4%. For maternal schooling, SII rose from 1.6% points (p.p.) for 1 + visit to 26.4 p.p. for 8 + visits. For 8 + visits, indigenous women showed the largest dropout rates and the lowest coverage (37.8%), whereas white women showed the opposite (74.7% coverage). The North region and adolescents also showed low coverage of 8 + ANC visits (50.8% and 55.4%, respectively). CONCLUSIONS: Increasing the number of recommended ANC visits exacerbates socioeconomic, racial, and regional inequities in Brazil, consistent with the inverse equity hypothesis. Higher coverage thresholds disclose wider inequities, thus further exposing the vulnerability of indigenous, with no formal schooling, adolescent women and residents of the North. Improved detection of such inequities is essential to guide policies that ensure high-quality ANC reaches all women and children, thereby eliminating current inequalities in maternal and newborn health outcomes. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12939-026-02811-4.