A new U.S. study has revealed that one in five pediatricians in the U.S refuse to treat unvaccinated children, Tech Times reports.

This practice is common among doctors in the Northeast and the South states that allow families to waive vaccinations due to religious beliefs and personal preferences.

Currently, there are 20 states in the U.S. where the law allows parents to waive mandatory children's vaccinations for philosophical reasons. The number with this legal loophole will drop in 2016 from 20 to 18 states, UPI reports.

"Even though the American Academy of Pediatrics discourages providers from dismissing families, some providers continue to do so. Instead of dismissing families, we need a better understanding of the reasons for vaccine refusal to find evidence-based strategies for communication that are effective at convincing hesitant parents to vaccinate," said lead author O'Leary, a specialist in pediatric infectious disease.

The study was conducted on 815 pediatric doctors and family physicians in 2012.

Nearly 66 percent of the doctors participated in the survey.

"I'm hearing the practice [of refusing care] has become more common, particularly in California, following the outbreak," said Sean O'Leary, a pediatric infectious disease specialist at Children's Hospital Colorado, told HealthDay, "Parents say, 'I don't want to take my child to a clinic with non-vaccinators and expose them to risk,' so there is parental pressure on some pediatricians."

The study revealed that 83 percent of pediatric doctors come across families who refuse vaccinations every month. When this happens, four percent of family doctors and 21 percent of pediatric doctors shared that they 'often' dismiss the families. 

The researchers published their findings in the Pediatrics journal on Nov. 2, 2015. The study was funded by the Centers for Disease Control and Prevention