# HIV Transmission Question **URL:** \ **Category:** Factual Questions\ **Created:** [April 22, 2014, 6:51pm UTC](https://boards.straightdope.com/t/hiv-transmission-question/686706 "2014-04-22T18:51:05Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![dolphinboy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dolphinboy/32/330_2.png) [@dolphinboy](https://boards.straightdope.com/u/dolphinboy)\ **Post date:** [April 22, 2014, 6:51pm UTC](https://boards.straightdope.com/t/hiv-transmission-question/686706/1 "2014-04-22T18:51:05Z")
Can a mother who is HIV+, whether being treated for that condition at the time or not, give birth to a baby that is not HIV+? I’m not talking about treating the baby with antivirals immediately after birth to suppress the virus, I mean that the baby is somehow born 100% free of the virus. Or does the fact that the baby was exposed for months to the mother’s blood mean that inevitably it will be born HIV+? I’m wondering if some babies have strong enough immune systems to counteract their exposure during pregnancy. ---
**Author:** ![Iggy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/iggy/32/3364_2.png) [@Iggy](https://boards.straightdope.com/u/Iggy)\ **Post date:** [April 22, 2014, 6:56pm UTC](https://boards.straightdope.com/t/hiv-transmission-question/686706/2 "2014-04-22T18:56:04Z")
Looks like even without treatment for the mother there is “only” a 25% chance that HIV would be passed to the fetus. With treatment the odds are much better. [Cite](http://aids.gov/hiv-aids-basics/prevention/reduce-your-risk/pregnancy-and-childbirth/) ETA: It probably has little to do with the baby’s immune system and more to do with how the placenta acts as a sort of barrier between the maternal and fetal blood supplies. ---
**Author:** ![SpoilerVirgin](https://avatars.discourse-cdn.com/v4/letter/s/4491bb/32.png) [@SpoilerVirgin](https://boards.straightdope.com/u/SpoilerVirgin)\ **Post date:** [April 22, 2014, 6:59pm UTC](https://boards.straightdope.com/t/hiv-transmission-question/686706/3 "2014-04-22T18:59:29Z")
According to [WHO](http://www.who.int/hiv/topics/mtct/en/): > [@](#): > > In the absence of any interventions transmission rates [from an HIV-positive mother to her child during pregnancy, labour, delivery or breastfeeding] range from 15-45%. I’ve also seen the figure of 25% cited above. It’s definitely not a sure thing. ---
**Author:** ![dolphinboy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dolphinboy/32/330_2.png) [@dolphinboy](https://boards.straightdope.com/u/dolphinboy)\ **Post date:** [April 22, 2014, 7:02pm UTC](https://boards.straightdope.com/t/hiv-transmission-question/686706/4 "2014-04-22T19:02:53Z")
Good answers. Thanks for the cite. I wonder why only 25% or so manage to contract it while the vast majority of babies don’t. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [April 22, 2014, 7:10pm UTC](https://boards.straightdope.com/t/hiv-transmission-question/686706/5 "2014-04-22T19:10:13Z")
It’s biology. There’s never any such thing as 100% or 0%. ---
**Author:** ![susan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/susan/32/17537_2.png) [@susan](https://boards.straightdope.com/u/susan)\ **Post date:** [April 22, 2014, 10:01pm UTC](https://boards.straightdope.com/t/hiv-transmission-question/686706/6 "2014-04-22T22:01:16Z")
As noted above, the placenta. The rate is up to 25% from untreated mom to child, with factors increasing the risk including vaginal delivery and breastfeeding. Hepatitis C can be transmitted vertically (mother to child) as well, and a mother with HCV and HIV has a higher risk of transmission.