Mother-to-child transmission is shortened and we call it MTCT.
A mother can pass HIV during her pregnancy. Nowadays, mothers with HIV are put onto ARVs (medication to slow down the virus and keep the immune system healthy) while pregnant as this acts as an effective barrier to prevent the baby from getting the virus directly from the mother.
Another way is during natural child delivery. Again, we have fought this battle and won- mothers who have HIV are given a dose of an ARV called Nevirapine to protect the new born baby from getting HIV. The baby is also given a few drops of an ARV to further protect him/her.
A mother can also give her baby HIV if she is breast feeding for a prolonged period of time. The rule is that 'breast is best' and that a mother who has HIV must not mix feed, that is, no food, formula, tea in conjunction with the breast milk. She must breast feed exclusively. Once she introduces solids or formula, she must stop breast feeding. The period that doctors and experts recommend is that for 6 months mothers can exclusively breast feeding.
If she continues to breast feed with mixed feeding, the baby has a higher chance of getting HIV.
It is not easy for a mother to transmit HIV to her child if she is on ARVs, nor in delivery if she is on ARVs. With breastfeeding if she is breastfeeding exclusively the baby will not get HIV easily. Only with mixed feeding does the risk get bigger if the mother continues to breast feed.