Why test in pregnancy? The principal purpose of testing a woman for HIV during pregnancy is to prevent any possible infection being passed on to her unborn child.  Mother to Child Transmission (MTCT) can occur during pregnancy, during labor and birth or through breastfeeding. However, with appropriate treatment and intervention, the chances of a child becoming infected can be reduced from around 25% to less than 2%. These days, in areas where antiretroviral therapy is available, testing in pregnancy also allows for the mother's infection to be identified and treated. This will enable her to remain healthy enough to care for her baby and see her child grow up.