How do stis affect pregnant women and their unborn babies?

Many ways: There are many adverse events that can happen w/ an infection during pregnancy. Depending on the type of infection, and at what point in the pregnancy it occurs, birth defects can occur. The baby can also become infected in the womb, or during delivery, leading to eyesight problems, neurodevelopmental disorders, toxic shock, etc. In short, it is important to prevent stis with safe sex practice.

Varies with disease: Some will infect the baby directly, causing miscarriage, organ damage or eventual disease and potential death. Some are only passed after the bag of waters open & baby is exposed during delivery. Things like herpes could trigger encephalitis and death. Chlamydia could cause eye disease or pneumonia, which could be deadly.It all depends on the disease.