This paper examined factors that influence the improvement in maternal health literacy among pregnant women in Paraguay, including those who did not complete compulsory education but participated in a community-based antenatal care program. Structured interviews were conducted to evaluate the pregnant women's maternal health literacy during their first, second, and third visits to the program in the Caazapa Region. The associations between individual maternal health knowledge scores and its gains, healthcare personnel capabilities, available health facility equipment, community social network, and living environment were analyzed by multiple regression analysis. The mean maternal health knowledge score from 124 women who completed three-consecutive assessments increased between the first and third interviews. Higher capabilities of healthcare personnel and better living environment were significantly related to gains in the maternal health knowledge score (p<0.01). Wider application of a community-based antenatal care program to meet the needs of those who are functionally illiterate in the standard language of the country, training for community healthcare personnel to improve capabilities, and resources for social network in the community would contribute to the improvement in maternal health literacy.