How is HIV passed on? a) HIV is passed on most commonly through unprotected sex – sex without a condom. b) HIV can be passed from a pregnant mother to her child – but this can usually be prevented if the mother takes anti-HIV drugs during pregnancy. c) HIV can also be passed on by blood coming into contact with infected blood – for example people sharing infected injecting needles. Blood transfusions have been safe in the UK for many years, but you might like to be aware if you have recieved a transfusion abroad as the standards are not guaranteed to be the same.