There were 59,796 babies born in Ireland last year - a 20% drop on the 2009 figure.
According to figures released by the CSO, there were over 70,000 births in 2009, 2010 and 2011 before the number began a decline - a trend that continued in the 2019 statistics.
The average age of a woman giving birth last year was 33, while the average age of a first-time mother was 31.3.
"There were 59,796 births registered in 2019, some 1,220 (or 2.0%) fewer than 2018 and a fall of 20.2% since 2009," explained Carol Anne Hennessy, statistician with the CSO.
"This represented an annual birth rate of 12.1 per 1,000 of population compared to 16.5 per 1,000 population in 2009."
While there were a decrease in births, there was a slight increase in deaths last year to 31,134, meaning there was a 'natural increase' in the population of 29,900.
Figures released today also showed that the number of same-sex marriages declined for the fourth year in a row. After peaking at 1,056, there were 640 same-sex marriages last year. The number of opposite-sex marriages has declined every year since 2014.