Herbert and Catherine Schaible face more than a decade in prison for the January 2009 death of their two-year-old son Kent.
Defense lawyers say the parents have been targeted because their fundamentalist Christian beliefs espouse faith healing.
Pennsylvania law says parents have a legal duty to protect their children's health and safety, although the law does not specify if or when medical care must be sought.
The Schaibles have six other children.
Experts say about a dozen children die in such cases each year.