If a birth mom is HIV positive, but the child at birth has tested negative for HIV at what point can you be certain the child will not develop HIV? What tests should be run on a baby or toddler to check their HIV status?

The test that is most commonly used to diagnose HIV infection in adults looks for antibodies to the virus. All HIV positive women make antibodies to the virus and pass them to their babies; it can take up to 18 months for uninfected babies to clear these antibodies from their blood. Thus, antibody tests can not be used to diagnose HIV infection in children under the age of 18 months.

In children under the age of 18 months, we use a technique called the polymerase chain reaction (PCR) to look for viral nucleic acids (genetic material) in the blood. In non-breastfed babies, this test can usually pick up HIV infection by 1-2 months of age. If a baby remains negative on this test at 3-4 months of age and the baby is not breastfeeding, the baby would be considered uninfected.