How long will it take before a babies is free of her mother's antibodies and be tested negative?

All pregnant women transfer their antibodies to their babies during pregnancy. The majority of this antibody transfer occurs in the last trimester of pregnancy which is why babies born very prematurely have very low levels of mothers antibodies. All HIV infected women will transfer their HIV antibodies to their babies but only 1 out of 4 babies will also be infected with the virus at the time of birth[ additional babies may become infected during the breastfeeding process]. All babies born to HIV infected mothers will be HIV antibody positive because of maternal antibodies and it can take up to 18 months for all of these maternal antibodies to completely disappear. Early in the HIV epidemic we only had antibody tests to make the diagnosis of HIV infection and in the case of mother to child transmission we had to wait untill mothers antibodies diappeared at 18 months of age to make the diagnosis. Currently, we can detect the virus itself using very sensitive HIV DNA or RNA tests and can make the diagnosis at birth or soon after. Unfortunately, these new tests are expensive and are not readily available in the developing world where antibody tests are still the most commonly used test for diagnosis of HIV infection.JLS.