Teenage girls are at increased risk of suicide if they are pregnant, a leading psychiatrist has warned.
She said while it was rare for a woman to take her own life during pregnancy, suicide after birth is the leading cause of maternal death overall.
"Adolescents are at a huge increased risk of committing suicide if they are pregnant. It's a leading cause of death in pregnancy and it's also rare," Prof O'Keane said.
"The reason it's rare is because all deaths in pregnancy are rare. Suicide post-partum is the leading cause of death overall."
According to Maternal Death Enquiry (MDE) in Ireland, funded by the Health Service Executive, Ireland has a maternal death rate of eight per 100,000 pregnancies for 2009 and 2010, the most recent years figures are available for.
The MDE report found two deaths by suicide but it also includes indirect and coincidental deaths during pregnancies such as cancer or road accidents in its figures.
The maternal death rate as previously reported by the Central Statistics Office was four in 100,000.
Prof O'Keane told a special Oireachtas health committee that most women who travel from Ireland to the United Kingdom for an abortion do so for mental health reasons.
She said there was therefore a clear need to legislate for abortion when a woman's life is in danger - including where there is a threat of suicide.
The Committee on Health and Children began three days of special hearings to help the Government draft new legislation for limited abortion.
Prof O'Keane was joined by Dr Anthony McCarthy, of the College of Psychiatry Ireland, and psychiatrist Patricia Casey, of the Mater Hospital, in sharing her clinical expertise.
Dr McCarthy insisted that while suicide rates among pregnant women were low, there was still a danger that a pregnant woman with mental illness or who is mentally distressed could be driven to suicide if she were unable to obtain a termination.
However, Prof Casey said it would be wrong to legalise abortion where there was a threat of suicide, saying abortion was not the answer to treating these women.
She also argued that such legislation would "open the floodgates" and lead to abortion on demand.
But she insisted she was not implying that women would manipulate doctors by pretending to be suicidal to get an abortion.
Last month, the Government announced plans to introduce a combination of legislation and regulation to legalise abortion in limited circumstances including when a pregnant woman is a suicide risk.
Its decision came on the back of an expert group report in November, which was compiled to set out options on how to respond to a European Court of Human Rights ruling on the so-called ABC case, which found that the state violated the rights of a woman in remission from cancer who was forced to travel abroad to terminate her pregnancy.
Its publication also coincided with the tragic death of pregnant Indian woman Savita Halappanavar, who miscarried 17 weeks into her pregnancy.
The 31-year-old contracted septicaemia and died at Galway University Hospital on October 28. Her husband Praveen has argued she was denied an abortion.
Prof O'Keane said such tragedies made the need for legislation more urgent.
"This debate is springing out of a need, a reality out of cases we have all lived with nationally and been traumatised by," she said.
The psychiatrist, who is also a professor at Trinity College Dublin, added: "If the limits of the legislation say it is only in extreme circumstances where the risk of suicide can only be avoided by a termination, obviously there's a need there."