In America today, children have no federal rights except under the “doctrine of imminent harm” which allows the child to be taken from the family if the child’s life is endangered by the parent. For the most part, being responsible for killing your own child, unless it’s for religious reasons it is against the law.
At least 30 states still allow parents to withhold lifesaving medical care to their children for religious reasons and children do die because of it. This may sound hyperbolic, but if you did withhold lifesaving medical care in a state that did not allow it for religious reasons, you’d be charged with killing your child. Parents have all the rights and children have no voice except for the guardian ad litem that speaks for them.