Self-medication during pregnancy is a common practice associated with significant risks for both the mother and the fetus. Pregnant women often use medications without medical supervision, driven by various individual and contextual factors. Understanding the determinants of this behavior is essential for designing preventive strategies and promoting safe medication practices. A narrative review was conducted using original articles published between 2015 and 2025, retrieved from PubMed. Inclusion and exclusion criteria were predefined, and the selection process was performed independently by two reviewers using the Rayyan platform, with validation by a third researcher. A total of 18 studies met the eligibility criteria and were included in the synthesis. The review identified multiple determinants of self-medication during pregnancy. These include obstetric factors (primiparity, multiparity, unplanned pregnancy), maternal age, level of education, previous history of self-medication, gestational age, limited access to health care, economic constraints, and cultural or religious beliefs. Additionally, the perception of symptoms as mild and the availability of over-the-counter medications were significant facilitators. Self-medication among pregnant women is influenced by a complex interplay of personal, socioeconomic, cultural, and healthcare-related factors. Addressing these determinants is crucial to promote rational drug use and protect maternal-fetal health.