Lily Allen has revealed she’s written a song about her 2010 miscarriage.

The unnamed track, which Lily described as, "really sad, really powerful", documents her experience of losing a baby boy 6 months into her pregnancy.

The Hard Out Here singer had already suffered a previous miscarriage in 2008 with then-boyfriend Ed Simons of band The Chemical Brothers.

Lily has since had two daughters with her husband Sam Cooper.

"I hope it makes the final cut, because it's a really important song to me," she said to Q Magazine of the tragic track, reports the Daily Express.

She also told the magazine that she wants her next album to be “relevant to other people.”

“It's no use just singing about being famous, or rhyming 'crazy' with 'baby' a million times over,” she explained.

"And I like to be frank, whether it's about sex or politics or feminism... but if people want to call it controversial, then, well, that's their thing."