Researchers say children in foster care have much worse health than children in the general population.
In 2014, more than 650,000 children in the U.S. spent time in foster care. On average, children in foster care spend 2 years waiting to be adopted.
Previous studies have suggested that children in foster care may develop physical and mental health issues, primarily as a result of the trauma they have experienced, such as abuse and neglect.
However, the authors of the new study - including Kristin Turney of the University of California-Irvine - note that no research has compared the health of children in foster care with that of children in the general population.
With this in mind, Turney and team analyzed 2011-2012 data from the National Survey of Children's Health, which included more than 900,000 children across the U.S. Of these, around 1.3 percent had been in foster care.
The researchers used logistic regression models to compare the risks of mental and physical health problems of children who had and had not spent time in foster care.
Foster care 'a risk factor for health problems in childhood'
On looking at the risks of physical health problems, the researchers found children who had been in foster care were twice as likely to have asthma and obesity and three times as likely to have hearing and vision problems, compared with children who had not spent time in foster care.
Behavioral problems were six times more likely among children who spent time in foster care, the team reports, and they were also at three times greater risk of attention deficit hyperactivity disorder (ADHD), and twice as likely to have learning disabilities and developmental delays.
Turney says their study makes an "important contribution to the research community" by being the first to demonstrate that the health of children in foster care is much worse than children in other living conditions.
"Our findings also present serious implications for pediatricians by suggesting that foster care placement is a risk factor for health problems in childhood," she adds.
"This is typically a difficult-to-reach population, so having access to descriptive statistics on their living arrangements, physical well-being and behavior provided an excellent opportunity to help identify the health challenges they face.
This study expands our understanding of the mental and physical health of these highly vulnerable children, but we must take a closer look if we are to understand how foster care really affects child well-being."