The baby quickly fell asleep in the driver's arms as emergency services were called.
Ivic then brings the baby aboard the bus, where another passenger lends the baby a jacket.
Authorities soon arrived at the scene and assisted the baby, who was unharmed.
A bus driver in Wisconsin was honored for saving a less than one-year-old child she found walking alone and barefoot on an overpass in Milwaukee in freezing temperatures.
Ms Ivic said she was grateful she was in the right place at the right time to keep the baby safe.
The child went missing after officials believe the child's mother had a mental health crisis, the transit system release said. When police gathered near his home, he noticed his child was not there and ran outside.
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The girl has now been reunited with her father.
Milwaukee police told WITI no charges were filed in the case.
"She did a lot more than her job".
"If it's a sad thing that its the ninth time than an MCTS driver has had to help a lost child get back to their family it is an extraordinary thing that we have drivers like Irena who are there to do it without hesitation", Abele added. "I don't take that kind of compassion for granted", said County Executive Abele. She has worked for the MCTS for five years.
When asked about what happened Ivic herself, who is originally from Serbia, told reporters, "If I find myself in same situation, I will of course help, always".
Editor's note: A previous version of this story from the Associated Press identified the child as a boy.