Unprotected sex with HIV-negative and untested people:

 

 

 

If you are living with HIV, using condoms during sex with people who know that they are HIV-negative or are unsure of their HIV status will protect them against HIV and protect both of you from STIs.

There's a lot of debate about how infectious people with HIV are if they are taking HIV treatment and have an undetectable viral load. Most experts agree that when HIV treatment is keeping viral load under control, the risk of HIV transmission is reduced to a low level, but that some risk still exists. 

 Sometimes, couples who are 'serodiscordant' (one has HIV and one does not), choose to have unprotected sex because they want to have a baby. It's a good idea to talk to your doctor about this option, so that you and your partner can make sure you are as healthy as possible before trying to conceive.

Source: aidsmap