The Irish singer and husband Brett Desmond welcomed their second child, also named Brett, on 4 January 2014.
According to reports, the birth took place at a hospital in Washington in the US before the family returned to Ireland.
A message on her official Facebook page read: "Andrea is delighted to share the news of the birth of her baby boy Brett - Born 04.01.14 @ 11am. Mother and baby are healthy and happy and back home with Dad and their daughter Jean."
The couple's first child, Jean, was born in April 2012.
Andrea married businessman Brett in County Clare, Ireland in August 2009. Her bridesmaids included sisters and bandmates Caroline and Sharon Corr, while the guest list featured celebrity friends such as Patrick Kielty and Bono.
More celebrities who have welcomed babies in 2014:
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