Introduction Anemia is a major public health problem affecting roughly 37% (32 million) of pregnant women worldwide. Anemia during pregnancy is a leading cause of low birth weight, preterm birth, and perinatal/neonatal mortality. Women in developing countries are at higher risk of anemia due to micronutrient deficiencies, hemoglobinopathies, infections, or other socio-demographic factors, especially among pregnant women. This study describes the trends and identifies factors associated with anemia among pregnant women aged 15-49 years old in Cambodia. Methods We analyzed data from the Cambodia Demographic and Health Survey (CDHS) for 2005, 2010, and 2014. Data were pooled across the three survey years for all pregnant women aged 15-49 years. Survey weights were applied to account for the complex survey design of the CDHS. Descriptive statistics were estimated for key sociodemographic characteristics of the study population. We ran bivariate and multivariable logistic regressions to assess factors associated with anemia among pregnant women aged 15-49 years old. Results Anemia in pregnant women aged 15-49 in Cambodia decreased from 56% in 2005 to 53% in 2014. Compared to pregnant women from the wealthiest households, women from poorest households were more likely to have anemia (AOR = 2.8; 95% CI: 1.76-4.9). Pregnant women from coastal regions were almost twice as likely of having anemia (AOR = 1.9; 95% CI: 1.2-3.0). Pregnant women were more likely anemic if they were in their 2 nd trimester (AOR = 2.6; 95% CI: 1.9-3.6) or 3 rd trimester (AOR = 1.6 95% CI: 1.2-2.3). Conclusion Anemia remains highly prevalent among pregnant women in Cambodia. Pregnant women from poorer households, those who were further along in the pregnancy, and those living in coastal and sea regions were at greatest risk of anemia. Public health interventions and policies to alleviate anemia should be prioritized and shaped to address these factors.