Objectives: To investigate pregnant women’s attitudes and behaviours towards hypertensive disorders of pregnancy and their treatment. Methods: Face-to-face, in-depth interviews were undertaken with 27 pregnant women diagnosed with and being treated for hypertensive disorders of pregnancy to investigate attitudes and behaviours regarding the conditions and their treatment. Written consent was obtained individually from each participant, and the interviews ranged from 16 to 54 minutes. Data collection was continued until thematic saturation was reached. Thematic analysis was employed to interpret the data. Results: Four major themes emerged around beliefs and behaviours of pregnant women regarding treatment of their hypertension: understanding of hypertensive disorders of pregnancy and their implications, risks versus benefits of antihypertensive medication during pregnancy, trust in medical professionals and adherence to medication. The women’s level of understanding of hypertensive disorders of pregnancy and their implications determined whether they were able to make informed decisions about their treatment. Prior experiences and concern for preservation of the pregnancy played major roles in the perception of the risk/benefit balance of using antihypertensive medication during pregnancy. The degree of trust in the treating medical professionals varied according to the perception of their confidence and knowledge. Conclusions: Sound understanding of the condition, a positive risk/benefit balance regarding antihypertensive medication use during pregnancy, and trust in medical professionals contributed to adherence to medication. Good communication with healthcare professionals is important to achieve optimal treatment.