From Family Structure and Children’s Health in the United States:

Highlights
Children in nuclear families [one or more children living with two parents who are married to one another and are each biological or adoptive parents to all children in the family] were generally less likely than children in nonnuclear families
• to be in good, fair, or poor health [Note: these three categories are considered “less than optimal”];
• to have a basic action disability;
• to have learning disabilities or attention deficit hyperactivity disorder;
• to lack health insurance coverage;
• to have had two or more emergency room visits in the past 12 months;
• to have receipt of needed prescription medication delayed during the past 12 months due to lack of affordability;
• to have gone without needed dental care due to cost in the past 12 months;
• to be poorly behaved;
• and to have definite or severe emotional or behavioral difficulties during the past 6 months.

h/t: FRC for pointing this out.