The figures show that the rate was 18% in University Hospital Kerry compared to just 8% in the National Maternity Hospital in Dublin.
The data for 2014 was extracted from the annual reports of the nine units where a total of 45,543 women were delivered.
Of those women, 8,520 were first-time mothers in spontaneous labour. Overall, one in eight of these women (12%) had an unplanned caesarean section delivery.
There were 7,367 women (16%) who were first-time mothers whose labour was induced or who had a caesarean section planned before labour started. Of the women in this group, 41% had a caesarean section.
The caesarean section rate for the women was between 37% and 45% in eight of the nine units, but in Mayo General Hospital, more than half (53%) were delivered by caesarean section.
The data was published at a major conference on the increasing use of caesarean section that took place at the Economic and Social Research Institute yesterday.
The data shows that University Hospital Kerry had the highest overall rate of caesarean sections at 33.6% while the National Maternity Hospital had the lowest at 23.5%. The overall rate was 29.5%.
Earlier, a leading midwifery expert said women should, as far as possible, avoid having a first caesarean section because of the risks involved.
A study of 2,800 first time mothers overseen by Prof Cecily Begley from the school of nursing and midwifery at Trinity College Dublin found that almost one in 10 women who underwent a Caesarean section developed wound infections.
The study — Maternal Health and Maternal Morbidity in Ireland (MAMMI) — found that women who had a caesarean section had to make repeat visits to their GP, 11% had to attend the maternity hospital’s emergency room, and almost 4% had to be re-admitted for treatment. Over half had wound pain in the first three months.
“A lot of women think that if they have a caesarean section they won’t have urinary incontinence afterwards but, at 12 months the rate will be the same, regardless of how the baby was born,” said Prof Begley.
Prof John Morrison, consultant obstetrician and gynaecologist at Galway University Hospital, said women needed to know about the increased risk of having a second caesarean section and that they could have a normal delivery.