Rebecca Bredow, from Michigan, was sentenced to seven days in prison for contempt of court after refusing to immunise her son because it goes against what she believes in.
In Michigan it is legal for parents to put off vaccinations due to personal beliefs.
However, Ms Bredow agreed with her former husband to have her nine-year-old son immunised in 2016 and was recently ordered by Judge Karen McDonald to follow through with the agreement.
More reading

New mums uncertain about vaccination
The anti-vaxxer told court that immunisation "goes against my beliefs".
"I would rather sit behind bars standing up for what I believe in, than giving in to something I strongly don't believe in," she also added.
Immunisation in the United States falls under state and local jurisdiction.
School’s have the ability to refuse a child’s attendance if parents don’t follow their vaccination guidelines.
Parents can also be jailed for truancy if they fail to meet these guidelines.
This is why anti-vaccination parents are choosing to homeschool their children, according to President of the National Vaccine Information Centre Barbara Fisher.