Background <p>The DECO-MOM mobile program was developed to enhance prenatal environmental health behaviors among pregnant women, addressing the challenges of climate change and environmental pollution. This pilot study aimed to assess the feasibility and preliminary impacts of the DECO-MOM app on personal and community health behaviors, quality of life, subjective health status, depression, anxiety, and e-learning satisfaction, guided by the revised protection motivation theory.</p> Methods/Design <p>This non-randomized controlled study employed a pre-post-test design with experimental and control groups. The study analyzed data from 31 participants in the experimental group and 34 in the control group after a four-week mobile application intervention conducted from September 26 to October 24, 2023, in three cities in South Korea.</p> Results <p>The experimental group demonstrated significant improvements in personal environmental health behaviors (<i>p</i> = .003), community environmental health behaviors (<i>p</i> = .001), quality of life (<i>p</i> = .043), and e-learning satisfaction (<i>p</i> = .005) compared to the control group. Significant increases were observed in subcategories such as lifestyle (<i>p</i> = .005), dust (<i>p</i> &lt; .001), reduction (<i>p</i> = .011), involvement (<i>p</i> = .007), recycling (<i>p</i> = .005), reuse (<i>p</i> = .035), content (<i>p</i> &lt; .001), and communication (<i>p</i> = .039). However, no significant increases were found in subjective health status, depression, or anxiety.</p> Discussion <p>The DECO-MOM app demonstrated feasibility and potential as a mobile health tool to promote environmental health behaviors among pregnant women. Future studies should explore the long-term effects, scalability, and integration of psychological support features to optimize outcomes.</p> Trial registration <p>Trial registration Number: KCT0007725, Registered September 22, 2022. Prospectively registered.</p>