Neonatal Intensive Care Units – NICUs – are one of those strange places in this world that everyone is happy exists, but also that everyone hopes they’ll never have to personally see the inside of. We all want our babies to be born timely and healthy, but if they’re not, it’s great that science has advanced to the point that fewer and fewer people have to go home from a maternity ward with empty arms.

If you are someone who ends up spending time in a NICU, you probably want to know as much as possible about the experience going in – so here’s what it means if you see a purple butterfly sticker while you’re there.

Image Credit: Mille and Lewis Smith

The concept was created by NICU parents Mille and Lewis Smith, who gave birth to twins at just 30 weeks gestation.

One of the girls, Callie, survived after a stay in the NICU but sadly the other, Skye, was born with a defect called anencephaly and only survived a short time after birth.

Image Credit: Millie and Lewis Smith

Millie and Lewis were given access to the Daisy Room Kingston Hospital in the U.K., a place where they could quietly marvel at their baby until they were forced to say goodbye. Since Skye was a twin, they actually chose to lay her next to her sister in her incubator for her last moments on earth.

After surviving this tragedy, but while Callie was still waiting to come home, something happened that sent Millie into an emotional spiral all over again.

Image Credit: Millie and Lewis Smith

While she spent time in the NICU, another mother made what she probably thought was an innocent comment about “be glad you don’t have twins.”

The Smiths weren’t angry at this woman, but they get an idea they hoped would save another couple from being shattered all over again during a fragile time – a purple butterfly sticker to indicate whether the parents connected to that baby had suffered a loss.

That way parents wouldn’t have to tell their story over and over, and other parents would know to be respectful.

The Smiths began fundraising and have had great success. Purple butterflies have started to pop up in hospitals all over the U.K. and hopefully plan to one day name their charity after their daughter, Skye.

Image Credit: Millie and Lewis Smith

If you’re moved by their story or perhaps have one of your own, you can donate to their foundation here.

And remember, if you see a purple butterfly in the NICU, be extra sensitive to the parents connected to it – you never know how your words will impact another.