How can hiv/aids not pass to a child a woman is carrying?

Treatment: One of the best successes in HIV treatment has been the reduction of maternal transmission to her fetus/newborn.If started and continued throughout the pregnancy, mom's viral load is minimized and transmission to baby can be cut down to 5% or less. C-section delivery is often chosen to avoid babies exposure to maternal blood.

Aggressive approach: It has been a standard to screen all pregnant women and start zidovudine therapy if tests positive. Hiv positive pregnant women also receive IV infusion of zidovudine while they are in labor. Elective c-section is preferred. Infants born to them receive 6-week zidovudine therapy as well. No breastfeeding allowed. This approach decreased the perinatal HIV transmission to less than 2 percent.