A new study finds the breast milk you buy over the Internet could be dangerous for your baby.

Researchers at Nationwide Children's Hospital teamed with Cincinnati Children's for the study. 

They bought samples of breast milk through a popular U.S. milk-sharing website and compared them to samples of unpasteurized, donated milk from a milk bank.

Dr. Michelle Medina with the Cleveland Clinic is concerned about the bacteria found in the breast milk.

"If you are somebody who wants to access these sites, who is thinking about actually procuring milk from these websites, you really have to think about that. How safe is this product that I am going to feed my baby?" Medina said.

Three out of every four internet samples had high bacteria counts compared to one in every four from the milk bank. 

Researchers blame poor collection, storage or shipping practices. The study can be found in the journal Pediatrics.