More than five million children in the United States have had a parent in prison and one in nine black children in the US will have a parent incarcerated at some point, according to a study released this week.

A new report published this week by Child Trends, a Maryland based research centre has found that one in 14 children in the US will at some point have a parent incarcerated, and for minority groups the figures are even higher.

With just five per cent of the world’s population, but one quarter of the world’s prisoners the US has seen its prison system expand rapidly and massively in recent decades, but until now there has been limited knowledge of the scale of the effect of this justice policy on the youngest generation of citizens in the country.

The most recent estimates of children affected by parental incarceration was less than two million, however the Child Trends study has included children who have previously had a parent incarcerated, as well as those whose parents are currently in prison. The study is based on data from the 2011-12 National Survey of Children’s Health.

The findings are a threefold increase in the most recent estimates, which only counted children who currently have a parent incarcerated.

Black, rural, poor - all more likely to see a parent in prison

The study found that parental incarceration “is most common among children who face other barriers to opportunity, such as those who are black, live in low-income families, or have parents with low education. Thus, the harm associated with parental incarceration can compound the already difficult circumstances of vulnerable children.”

Black children are twice as likely to have a parent in prison as white children, with 11.5% of all black children – one in nine – having a parent in prison at some point during their childhood. If that sample is narrowed by just looking at black teenagers the difference grows even starker. One in seven of black children age 12-17 have, or has, had a parent incarcerated.

The study again warns that this is likely an underestimate, as there are a high proportion of single parent families in the black community in the US, and the study doesn’t include parents who do not live at home with their kids.

Location also plays a significant factor, with children in rural areas almost twice as likely to face the situation as those in metropolitan areas – 10.7% to 6.3%.

Economic factors are also a major player, with children living in poor families three times more likely to endure parental incarceration as those in high income families.

The long-term effects of parental infcarceration

“The debate is too often all about the people in prison,” David Murphey, a senior researcher at Chld Trends, told the Washington Post.

“We’d do well to shine a light on the collateral effects — the families,” he added.

While the researchers admit that “it can be difficult to identify the unique effects of parental incarceration”, because there are more often than not a range of problems already in the child’s environment, they do point to a series of knock-on effects - including future mental health problems, education issues and, down the line, their problems with the law.

Some of these effects seem somewhat unsurprising - a child with at least one parent in prison will be under less supervision and is more likely to have problems in school. But there are deeper problems, including higher chances of health problems as a child and an adult – including being more susceptible to depression, asthma and anxiety.

While suggesting that “the best long-term solution might be to reduce reliance on imprisonment as a sanction for some categories of criminal behaviour” the researchers say there are some small steps that might limit the damaging effects of parental incarceration. These include increased communication between incarcerated parents and their children, and making prison visits more friendly for children.

While 99% of incarcerated parents are fathers, the report warns that “the number of women in prison and their percentage of the incarcerated population have both been growing.”

While US incarceration numbers are declining they remain the highest in the world of all countries who report such figures.

The US Justice Department has announced it will release 6,000 inmates from prison early, in the hope of easing overcrowding and offering reprieve for prisoners who were handed overly heavy sentences in the past 30 years.