SummaryBackgroundLatin America and the Caribbean present the second highest adolescent fertility rate in the world, only after sub-Saharan Africa, and have reached the third position globally in the incidence of motherhood in adolescence. We aimed to explore trends and inequities in adolescent childbearing in the region.MethodsWe used nationally representative household surveys from Latin American and Caribbean countries to address trends in early childbearing (proportion of women having their first livebirth before age 18 years) over generations and in adolescent fertility rates (AFRs; livebirths per 1000 women aged 15–19 years) over time. For early childbearing, we analysed the most recent survey conducted since 2010 from 21 countries (2010–20); for AFR, we analysed nine countries with two or more surveys, with the most recent being conducted from 2010 onwards. For both indicators, variance-weighted least-square regression was used to estimate the average absolute changes (AACs) at the national level and by wealth (bottom 40%vstop 60%), urban versus rural residence, and ethnicity.FindingsAmong 21 countries studied, we noted a decrease in early childbearing along generations in 13 of them, with declines varying from –0·6 percentage points (95% CI –1·1 to –0·1) in Haiti to –2·7 percentage points (–4·0 to –1·4) in Saint Lucia. We observed increases over generations in Colombia (1·2 percentage points [0·8 to 1·5]) and Mexico (1·3 percentage points [0·5 to 2·0]) and no changes in Bolivia and Honduras. The fastest early childbearing decline occurred among rural women, whereas no clear pattern was observed for wealth groups. Decreasing estimates from oldest to youngest generations were found among Afro-descendants and non-Afro-descendant and non-indigenous groups, but results were mixed for indigenous people. All nine countries with data for AFR presented reductions over time (–0·7 to –6·5 births per 1000 women per year), with the steepest declines observed in Ecuador, Guyana, Guatemala, and the Dominican Republic. In general, adolescents in rural areas and the poorest adolescents had the largest reductions in AFR. If current trends persist, by 2030 most countries will present AFR values ranging between 45 and 89 births per 1000 women, with notable wealth-related inequalities.InterpretationOur results indicate a reduction in AFR in Latin American and Caribbean countries that was not necessarily accompanied by a decrease in early childbearing overall. Large inequalities both between countries and within countries were observed, with no clear reduction over time. Understanding trends in adolescent childbearing and its determinants is essential for planning and designing programmes to ensure the desired reductions in rates and gaps across population subgroups.FundingPAHO, Bill & Melinda Gates Foundation, and Wellcome Trust.TranslationsFor the Spanish and Portuguese translations of the abstract see Supplementary Materials section.