One in five births were to cohabiting couples and more than 35% in total were outside marriage in the third quarter of last year, according to new figures from the Central Statistics Office.

Of the 17,729 babies born in July to September 2013, 6,243 were to unmarried parents – an increase from the same period last year. More than 3,500 of those were born to cohabiting parents, representing 20% of total births, while 2,698 were born to parents who did not live at the same address, or 15.2% of the total.

Perhaps even more notably, of the 3,491 babies born to mothers aged 25-29, the majority (52%) were born outside of marriage.

The highest proportion of births outside marriage was in Limerick city, which with a figure 49.7% is getting close to having a majority of births each year taking place outside marriage. Cork, Dublin and Waterford cities also had high numbers of children born outside marriage, with figures of 46.9%, 47.7%, and 44.6% respectively. The lowest percentage of births outside marriage/civil partnership was in Galway County at 21.6%.

The birth rate for the quarter represents an annual birth rate of 15.4 per thousand of the population, a slight decrease on the previous year.