Young prisoners should be given better access to their families, Cherie Booth QC has said.
The PM's wife is calling for fewer young parents to be sent to jail
The prime minister's wife suggested it could help prevent offenders' children from becoming criminals themselves.
Speaking at the launch of a Prison Reform Trust report she also said that alternatives to jail were needed for some young parents.
The study suggests that as many as 7 in every 100 primary school children has a parent in jail.
'Cycle of misery'
Ms Booth said fatherhood was currently a "hot topic" at the launch of the report - Young Parents, From Custody to Community, which is based on a three-year research project with young prisoners around the UK.
"Imprisonment too often worsens rather than tackles problems," she added.
No specific research has been carried out to assess whether the children of young prisoners were more likely to offend later in life, the report says.
However, it points to a general survey of prisoners showing 43% had a relative who had also been convicted of a criminal offence.
Director of the Prison Reform Trust Juliet Lyon said the government should do more to prevent a "cycle of misery and crime" being established.
She said: "Crime doesn't have to run in the family. Work to support vulnerable young parents who offend offers a unique opportunity, not only to help them get out of trouble, but also to become the good parents most want to be."
'Breaking up families'
Around 40% of young female offenders and a quarter of young male offenders are believed to be parents.
Government figures show young fathers in custody who maintain contact with their family are six times less likely to re-offend after release.
However, the trust's report revealed maintaining contact was sometimes difficult because prisoners were held on average more than 50 miles away from their homes.
The Young Parents project manager Joanne Sherlock said their study showed families were being put under strain.
"The government is in danger of jeopardizing the prospects of future generations and breaking up families through its failure to meet the needs of young parents in prison," she said.
The trust is calling on the Department for Education and Skills to work with the Home Office to improve support for young prisoners, their children and partners.
It also wants young parents to be given more opportunities to find employment and housing once they leave custody.