Can a UTI bacteria of a pregnant woman affect her baby?

UTI. Infections in pregnancy are very common, but not likely to hurt a child but i advise seeing your OB and being checked.
Premature labor. Pyelonephritis or a kiney UTI can induce early labor resulting in a preterm delivery. Bacteria causing UTI should not otherwise affect baby.
Not likely. Unless the mom becomes critically ill, baby is likely okay. Always consult with md before starting antibiotics, some of which are unsafe for the baby. Some women are found to continually have bacteria in the urine, without symptoms of infection, and this can increase the risk of preterm labor. Routine prenatal care is essential!