Purpose: This study aimed to explore the meaning of pregnancy myths and how they contribute to the oscillation of health behaviors among pregnant women in the context of stunting risk in Samarinda, Indonesia.

Methodology: A qualitative study using a phenomenological approach was conducted with 278 pregnant women from two sub-districts with the highest prevalence of stunting, Loa Janan Ilir and Loa Bakung, with data collected over three months through in-depth interviews at five primary healthcare centers and analyzed using Colaizzi's method to identify significant statements, formulate meanings, and develop thematic structures.

Results: Pregnancy myths function as behavioral regulators, particularly through restrictions on sleep, including prohibitions against frequent sleeping, morning sleep, and daytime naps, and dietary practices, including avoidance of banana blossom, squid, octopus, and cold beverages, and these beliefs contribute to an oscillation of health behaviors characterized by irregular sleep patterns and inconsistent dietary intake.

Conclusions: Pregnancy myths contribute to the emergence of oscillating health behaviors among pregnant women, which may increase the risk of stunting, and culturally sensitive health interventions are needed to bridge traditional beliefs with evidence-based maternal health practices.

Limitations: The cross-sectional, self-reported design cannot establish causal links to measured nutritional or growth outcomes, and findings from two sub-districts may not transfer directly to other sociocultural settings.

Contributions: The study introduces health behavior oscillation as a novel conceptual pathway linking cultural belief systems to maternal health practices and stunting risk.