Few studies have addressed relationships between health literacy (HL) and nutritional awareness in preconception/pregnancy populations, especially within Asia. We explored the rationale for nutrition-related education and/or HL interventions to improve nutritional intake among preconception/pregnant women. A cross-sectional questionnaire-based real-world study was conducted among 100 preconception and 200 pregnant women in Vietnam in January/February 2022. The questionnaire included a validated screening tool for HL (Newest Vital Sign [NVS]), and questions on preconception/pregnancy-related nutritional knowledge and behavior, prenatal supplementation, sources of nutritional advice. Most respondents (62%) had limited HL and only 5% had adequate HL. Respondents with limited HL (NVS 0-1) showed less awareness of benefits of healthy eating before/during pregnancy, such as reduction in risk of birth defects. Most (94%) considered prenatal supplements beneficial, yet 64% were not convinced of supplement safety. The limited HL group reported the lowest use of supplements, including multivitamins, iron, and folic acid/folate. The prevalence of limited HL and the low awareness of preconception/pregnancy-related nutrition suggest an urgent need to invest in nutrition-specific education and improving HL in maternal populations. This will help support adequate maternal nutrition and appropriate micronutrient supplementation before conception and throughout the "first 1000 days" of life.