Was told people who are hiv positive run a high risk of infection when around a pregnant woman or a baby..why would this be?

See below: Around pregnant women, their immune systems are ramped down a bit due to the pregnancy and can cause them to be more susceptible to infections - as with babies who are developing their immune system and are exposed more often due to proximity of other children with daycares, schools and older sibs and thus will be sick more often. Thus, people with HIV would be exposed to more infections.