Despite women's awareness that drinking alcohol in pregnancy can lead to lifelong disabilities in a child, it appears that an awareness alone does not discourage some pregnant women from drinking. To explore influences on pregnant women's choices around alcohol use, we conducted interviews and group discussions with 14 Indigenous Australian and 14 non-Indigenous pregnant women attending antenatal care in a range of socioeconomic settings. Inductive content analysis identified five main influences on pregnant women's alcohol use: the level and detail of women's understanding of harm; women's information sources on alcohol use in pregnancy; how this information influenced their choices; how women conceptualised their pregnancy; and whether the social and cultural environment supported abstinence. Results provide insight into how Indigenous Australian and non-Indigenous pregnant women understand and conceptualise the harms from drinking alcohol when making drinking choices, including how their social and cultural environments impact their ability to abstain. Strategies for behaviour change need to: correct misinformation about supposed 'safe' timing, quantity and types of alcohol; develop a more accurate perception of Fetal Alcohol Spectrum Disorder; reframe messages about harm to messages about optimising the child's health and cognitive outcomes; and develop a holistic approach encompassing women's social and cultural context.