Descriptive summary of study sample.

Adolescent girls and young women (AGYW) in sub-Saharan Africa (SSA) face heightened risks of adverse sexual and reproductive health outcomes. Water insecurity may contribute to these vulnerabilities by creating social and environmental stressors that undermine reproductive health and rights, yet this relationship remains understudied. This study examined associations between water insecurity and reproductive health outcomes among AGYW in 29 SSA countries, using recent Demographic and Health Survey data. Modern contraceptive use, early sexual initiation, and early childbirth were assessed as reproductive health indicators, while the type of water source and time required to reach the water source served as measures of water stress. A total of 162,077 AGYW were included. Binary multivariable logistic regression models were used to estimate the associations between water insecurity and reproductive health outcomes. AGYW with access to improved drinking water sources were 16% more likely to use modern contraceptives (AOR = 1.16; 95% CI: 1.10 - 1.22), 7% less likely to report early sexual debut (AOR = 0.93; 95% CI: 0.88 - 0.98), and 6% less likely to have a first birth before age 18 (AOR = 0.94; 95% CI: 0.89 - 0.99) compared with those relying on unimproved sources. Additionally, those who spent 30 minutes or less travelling to their water source were 7% more likely to use modern contraceptives (AOR = 1.07; 95% CI: 1.02 - 1.13) and were slightly less likely to initiate sexual activity before age 15 (AOR = 0.98; 95% CI: 0.92 - 1.03). These findings suggest that water insecurity may play a meaningful role in shaping AGYW’s reproductive health in SSA. Consequently, addressing water insecurity and related stressors could support improved reproductive health outcomes and strengthen efforts to protect the well-being and rights of AGYW.