The number of births in Co Leitrim fell by almost 9 per cent last year.
They also fell significantly in Co Roscommon, according to the CSO.
There were 346 births registered in Co Leitrim last year - down from 381 in 2024.
Of last year's, 31 of the mothers were aged over 40, and one was under 20.
Births also fell in Co Roscommon, dropping from 687 in 2024 to 670 in 2025.
A total of 60 of last year's mothers were over 40, and six were under 20.
The trend was slightly different in Longford - with births rising from 472 in 2024 to 486 last year.
A total of 35 of last year's mothers were over 40, and 12 were under 20.