Serina Marie Brock, 20, is charged with endangering the welfare of a minor and her son is now in state custody.
Brock allegedly failed to take her baby boy to required doctor visits setup to monitor his progress after he was determined to be underweight.
Police say Brock was told to bring the child to the doctor once a week but had stopped doing so in September.
The child's grandmother eventually became concerned last week and took him to the doctor herself. A police incident report says the baby boy weighed in at nearly 10 pounds, and medical staff noted he should be closer to 16 pounds at his age and height.
When clinic staff called Brock, she allegedly hung up on them and refused to answer calls thereafter.
Two other juveniles were removed from Brock's home when the baby was taken into state custody, according to police.