Luke Bryan's infant niece has died.

The 40-year-old country singer and his wife Caroline are in mourning after Caroline's brother Bo Boyer and his wife Ellen, tragically lost their daughter Sadie Brett earlier this week.

The tot was born last summer with cardiac issues and Ellen revealed on social media recently that her health was declining.

She wrote: ''10 steps forward.. 5 steps back. I'm trying to stay positive and say at least we're still ahead of where we were 10 days ago.. And we are, but today has been a tough day. Brett seems to have an infection of some sort. The team is leaning toward blood infection/sepsis. Her blood pressures and her temp have been really low today and got pretty scary low around 3. She is on several antibiotics so our prayer is that they will be the correct ones to treat this infection.''

She added earlier this week, ''Please- Please pray with us. Please pray for this infection to clear and for her liver to be able to work properly.''

Following Sadie's death, Luke took to Twitter to thank fans for their support.

He wrote: ''We thank all of you for your prayers. Love y'all.''

This is just the latest family tragedy for the Luke, who released the song 'Drink A Beer' in 2013 as a tribute to his late siblings.

Luke's brother Chris died in a car accident in 1996 and his sister Kelly passed away suddenly in 2007. Her husband Ben later died in 2014.