BACKGROUND:Non-adherence with medications in pregnancy is increasingly recognized and often results in a higher rate of preventable maternal and fetal morbidity and mortality. Non-adherence with prophylactic aspirin amongst high-risk pregnant women is associated with higher incidence of preeclampsia, preterm delivery and intrauterine growth restriction. Yet, the factors that influences adherence with aspirin in pregnancy, from the women's perspective, remains poorly understood. OBJECTIVE:The study is aimed at understanding the factors, from the women's perspective, that influenced adherence with prophylactic aspirin in their pregnancy. STUDY DESIGN:A sequential-exploratory designed mixed methods quantitative (n = 122) and qualitative (n = 6) survey of women with recent high-risk pregnancy necessitating antenatal prophylactic aspirin was utilized. Women recruited underwent their antenatal care in one of three high-risk pregnancy clinics within the South Western Sydney Local Health District, Australia. The quantitative study was done through an electronic anonymous survey and the qualitative study was conducted through a face-to-face interview. Data obtained was analysed against women's adherence with aspirin utilizing phi correlation (φ) with significance set at <0.05. RESULTS:Two key themes, from the women's perspective, that influenced their adherence with aspirin in pregnancy were identified; (1) pill burden and non-intention omission (2) communication and relationship with health care provider (HCP). Pill burden and its associated non-intentional omission, both strongly corelated with reduced adherence (Φ = 0.8, p = 0.02, Φ = 0.8, p<0.01) whilst the use of reminder strategies minimized accidental omission and improved adherence (Φ = 0.9, p<0.01). Consistent communication between HCPs and a good patient-HCP relationship was strongly associated with improved adherence (Φ = 0.7, p = 0.04, Φ = 0.9, p = <0.01) and more importantly was found to play an important role in alleviating factors that had potentials to negatively influence adherence with aspirin in pregnancy. CONCLUSION:This study identified factors that both positively and negatively influenced adherence with aspirin amongst high-risk pregnant women. Is highlights the importance in recognizing the impact of pill burden in pregnancy and the need to counsel women on the utility of reminder strategies to minimize non-intentional omission. Importantly, it emphasizes on the importance of a positive patient-HCP relationship through effective and consistent communication to achieve the desired maternal and fetal outcomes.