Might a newborn baby be at any risk living with someone infected with hiv?

HIV. Hiv is transmitted through sexual contact and blood. As long as you are using universal precautions there should be no problem. Good hand washing, properly disposing any items with blood or other secretions, etc.
Passed through fluid. Hiv is passed through body fluids (blood, saliva, semen, etc), so just living with a person does not put them at increased risk of the disease. People with HIV may have reduced immunity and therefore may contract more illnesses than others- these may pose a risk to the baby who also have reduced immunity. Practice good hygiene and hand washing and keep baby away when others are sick.