This study compares drug use, injecting and sexual risk-taking behaviour among pregnant injecting drug users (IDUs) enrolled in methadone maintenance treatment (MMT), non-pregnant women IDUs enrolled in MMT and women IDUs not enrolled in treatment. There was no significant difference between pregnant IDUs enrolled in MMT and women IDUs not enrolled in treatment in terms of their injecting risk-taking behaviour. Both groups reported significantly higher levels of injecting risk-taking behaviour compared to (non-pregnant) women enrolled in MMT. Pregnant women enrolled in MMT reported a significantly lower methadone dose compared to non-pregnant women in MMT. There was a trend for pregnant women enrolled in MMT to report a higher level of heroin use compared to non-pregnant women in MMT. The lack of evidence for a difference in level of injecting risk-taking behaviour between pregnant IDUs enrolled in MMT and women IDUs not enrolled in treatment suggests the need for additional strategies among pregnant IDUs to reduce IDU and injecting risk-taking behaviour. Possible strategies include maintenance on higher doses of methadone and the application of relapse prevention strategies.