It was a simple passing comment from one new mother to another, but it broke Millie Smith's heart.
Millie's daughter Skye died shortly after birth on April 30. A few days later the grieving mother was caring for Skye's twin sister Callie in a hospital neonatal ward when the another parent made the remark that devastated her.
"There were three sets of twins crying," Millie told BBC.
"A parent who didn't know what I'd been through turned to me and said, 'You are so lucky you don't have twins.'
"When she said this to me, it just broke me. I know the mother would have felt bad if she knew how her words affected me."
Millie, from Surrey in the UK, was determined to prevent other grieving parents from being hurt by well meaning comments from strangers.
"I felt there should be something like a small symbol to let people know that my baby had died," she said.
"I thought of a butterfly coloured purple, for either a girl or boy, that could be put on cots."
The family's local hospital immediately adopted the idea of purple butterfly stickers and Millie now hopes to get the concept into all hospitals across the UK.
"Instead of stickers, the butterflies will be printed on card and laminated, and each hospital would have a template to make these themselves," she told BBC.
"Also, this allows parents to take the card home in their memory box."
Millie was 12 weeks pregnant with Callie and Skye when she learnt one of her babies had anencephaly and would not survive long after birth. Anencephaly is a condition where a baby's skull does not form properly and leaves the brain exposed.
"The doctors informed us ... that no baby had ever survived this, it was impossible. We made the decision to continue with the pregnancy to give Callie a fighting chance - although it was high risk, we wanted to try," Millie wrote on the Skye High Foundation Facebook page.
"At 30 weeks pregnant, 10 weeks early, I went into labour. On the 30th April 2016 my beautiful girls were born ... Callie was rushed to intensive care and we got to spend 3 amazing hours with Skye before she passed away.
"When Skye passed it felt like my world had ended. Even though I had Callie, my heart was broken."
Callie is now healthy and thriving two-month-old.
In addition to promoting the butterfly cards, Millie hopes the Skye High Foundation will be able raising money to help pay for counsellors for grieving parents.
"I was fortunate to have a bereavement midwife," Millie told BBC
"She was there during the birth, when Skye passed away, and when I'm having a bad day.
"But she is not a counsellor, and I think it is important that counselling is available."
Millie says her main aim is for people to acknowledge babies who have died.
"People don't talk about a loss of a baby - they feel awkward," she said.
"Even some nurses didn't know what to say.
"The thing I am most proud of is that it has got people talking about it.
"I want to support families, the butterfly idea, and anything else that can make a difference."