Nearly one in three women who gave birth in the Coombe maternity hospital in Dublin in 2011 had an unplanned pregnancy.
One in every two mothers opted for a pain-relieving epidural to see them through labour.
The hospital annual report said 2011 was the busiest in its 185-year history, with 9,315 mothers attending and 8,536 births.
There has been a steady increase in obstetrical complications, such as serious loss of blood after vaginal delivery and spontaneous labour in first-time mothers.
Up to 42 mothers were classified as having serious maternal illness. The induction rate was 33.3pc, which was the highest over seven years.
Four in 10 women were first-time mothers.
An estimated 13pc of the women had a history of psychiatric disorders, and 17.2pc were classified as obese, compared to15.6pc the previous year.
More than one in 10 had a previous caesarean section while the rate of surgical delivery for the hospital as a whole was 27.7pc.
The hospital's report said there has been no increase in the birth weight categories over the past seven years, despite more mothers being obese.
There were 313 sets of twins, 21 sets of triplets and four sets of quads born at the hospital during the year.
The report said that among the hospital's challenges is the increasing number of appointments and increasingly complex cases at a time of diminishing resources.
It also needed to provide a standard of care required for the increasing numbers of women who need care for diabetes in pregnancy, a significant number of whom do not speak English.
The Coombe was among the hospitals which bid to be the site of the new national children's hospital, but it was turned down.
The hospital will benefit from having the children's hospital built in the campus of St James's Hospital, which is also in the south inner city.