Amazonian populations are increasingly exposed to climatic shocks, yet knowledge of related health impacts is limited. Understanding how health risks are coproduced by local climatic variability, place and social inequities is vital for improving decision-making, particularly in decentralized contexts. We assess the impacts of rainfall variability and multiscale vulnerabilities on birth weight, which has lifelong health consequences. We focus on highly river-dependent areas in Amazonia, using urban and rural birth registrations during 2006–2017. We find a strong but spatially differentiated relationship between local rainfall and subsequent river-level anomalies. Using Bayesian models, we disentangle the impacts of rainfall shocks of different magnitudes, municipal characteristics, social inequities and seasonality. Prenatal exposure to extremely intense rainfall is associated with preterm birth, restricted intra-uterine growth and lower mean birth weight (≤−183 g). Adverse birth outcomes also follow non-extreme intense rainfall (40% higher odds of low birth weight), drier conditions than seasonal averages (−39 g mean birth weight) and conception in the rising-water season (−13 g mean birth weight). Babies experience penalties totalling 646 g when born to adolescent, Amerindian, unmarried mothers that received no formal education or antenatal or obstetric health care. Rainfall variability confers intergenerational disadvantage, especially for socially marginalized Amazonians in forgotten places. Structural changes are required to reduce inequities, foster citizen empowerment and improve the social accountability of public institutions.

亚马逊河人口越来越多地遭受气候冲击，但是对相关健康影响的了解却很有限。了解当地气候变化，地点和社会不平等如何共同产生健康风险，对于改善决策尤其是在权力下放的情况下至关重要。我们评估降雨的可变性和多尺度脆弱性对出生体重的影响，这会对终身健康产生影响。我们将重点放在亚马逊河流域高度依赖河流的地区，使用2006-2017年期间的城市和农村出生登记。我们发现局部降雨与随后的河流水位异常之间存在强烈的但在空间上存在差异的关系。使用贝叶斯模型，我们可以解开不同强度，市政特征，社会不平等和季节性的降雨冲击的影响。产前暴露于极强的降雨与早产，子宫内生长受限和平均出生体重降低（≤−183 g）有关。不利的分娩结果还取决于非极端的强降雨（低出生体重的几率高40％），比季节平均水平（−39 g平均出生体重）更干燥的条件以及在上升水季节受孕（平均出生体重−13 g） 。未接受正规教育，产前或产科保健的青春期，美洲印第安人，未婚母亲所生的婴儿总共受到646克的罚款。降雨的多变性赋予代际劣势，尤其是对于那些在被遗忘的地方处于社会边缘地位的亚马逊人而言。需要进行结构性改革，以减少不平等现象，增强公民权能并改善公共机构的社会责任感。