Residents of church-run homes for unmarried mothers and their children in Northern Ireland suffered a "lifetime of trauma", Stormont's First Minister has said.

A "victim-centred" independent investigation was ordered and Arlene Foster pledged the voices of survivors would be heard "loudly and clearly".

A research report into operation of the institutions examined eight mother and baby homes, a number of former workhouses and four Magdalene laundries.

Mrs Foster said: "It is with huge regret that we acknowledge the pain of those experiences and the hurt caused to women and girls who did nothing more than be pregnant outside of marriage, some of them criminally against their will.

"None of us should be proud of how our society shunned women in these circumstance and of their experiences while resident in these institutions."

More than 10,500 women entered mother and baby homes over a 68-year period from 1922.

Around a third of those admitted were aged under 19 and most were from 20-29.

A number were the victims of sexual crime, including rape and incest.

Mrs Foster added: "The research report to be published later today is only the start of a process to allow the long-silenced voices of women and their children to be heard.

"For too long they have carried a burden of shame and secrecy.

"Too often their treatment from those who were in positions of power and trust caused them real harm and a lifetime of trauma."

Around 4% of babies were either stillborn or died shortly after birth across the entire period.

The research report does not reach firm conclusions about rates of infant mortality in mother and baby homes, the DUP leader added.

An estimated 32% of infants were sent to baby homes following separation from their birth mother.

Other babies were boarded out - fostered in today's terms. Others (around a quarter of babies) were placed for adoption.

Research was undertaken by a team of academics from Queen's University Belfast and Ulster University.

It gives an account of individual and collective experiences of the institutions and highlights the need for further examination of a number of important issues, including adoption and infant mortality rates.

Ministers have agreed that the independent investigation should be shaped by survivors through a co-design process, which will be facilitated by experts and completed within six months.

Mrs Foster said the voices of survivors had been silenced for too long.

She added: "That was a significant wrong.

"As a society we must acknowledge this and do all we can to bring the truth of your experience into the open."

She said it was with deep regret that she acknowledged the pain of those experiences and the hurt caused to women and girls who did nothing more than be pregnant outside of marriage, some of them because they were victims of criminal acts.

"It was shameful how so many of these women were treated.

"The accounts of cold and uncaring treatment are truly harrowing and the separation of mothers from their children a terrible legacy."

Deputy First Minister Michelle O'Neill said the report gave a "sad and troubling" insight into the lived experiences of the thousands of women and girls, and their now adult children, who suffered in these institutions.

"The harsh treatment of these women was cruel, unjust and inhumane.

"As a mummy, my heart breaks for the women and girls who did no wrong, whose rights were ignored and whose children were so cruelly taken from their arms.

"For those children who never knew their mothers, who for too long have been kept in the dark.

"They were failed on every level and we cannot allow them to be failed any longer."

A Church of Ireland spokesperson said the publication of the research report on Mother and Baby Homes and Magdalene laundries in Northern Ireland "sheds further light on the suffering of women and children in relation to their experiences in these homes".

"The Church of Ireland will be giving the report further careful consideration, as it has done with the recent report in the Republic of Ireland," they said.

"We appreciate the extensive work undertaken by the researchers in the Department of Health."