Iron-deficiency anemia is common during pregnancy and can lead to serious health consequences for mothers and babies. Antenatal iron supplementation has been associated with lower anemia prevalence and improved pregnancy outcomes and is recommended by WHO to all pregnant women via daily oral iron (30-60 mg) and folic acid (0.4 mg) supplements. Nevertheless, data on uptake and adherence to iron supplementation among pregnant women in many countries tends to be outdated and fragmented, with few studies having comprehensively summarized barriers and facilitators to supplementation. We conducted a secondary analysis of demographic and health surveys from 69 low- and middle-income countries, to determine uptake and adherence to iron-containing supplements among pregnant women and explore associations between socio-demographic characteristics and antenatal care and supplements consumption. Results show that 86% of all respondents reported receiving iron supplements during pregnancy, and that, among those receiving the supplements, 46.1% reported consuming 90 or more supplements, while 23.3% reported 120 or more, and 7.1% 180 or more. Higher education, wealth, and access to media were strongly associated with higher odds of initiating iron supplementation (OR: 1.32; 95%CI: 1.25-1.38; OR: 1.29; 95%CI: 1.20-1.38; OR: 1.15; 95%CI: 1.05-1.26 respectively) and adhering to the regimen (OR: 1.16; 95%CI: 1.12-1.21; OR: 1.21; 95%CI: 1.13-1.30; OR: 1.14; 95%CI: 1.08-1.20 respectively). Finally, attending antenatal care, and especially attending earlier during the pregnancy, was associated with higher odds of consuming the supplements. Country-specific antenatal care guidelines are needed to provide clear guidance on the timing and frequency of antenatal care attendance and supplementation.