Ms Curtis now runs a charity – The Lily Foundation – which supports families and raises money for research into mitochondrial diseases.
She told Sky News why she supported the decision by the fertility regulator to approve the so-called ‘three-parent baby’ treatment to prevent inherited diseases.
Lily was just seven weeks old when she was diagnosed with a mitochondrial disease.
Following a number of seizures, she was admitted to intensive care at the Evelina Children’s Hospital in London.
It was here that we were told about the disease, for which there is no treatment and no cure.
It was here that we learned she was going to die.
Lily was on a ventilator at the time and we asked how long she had left with us.
The answer was: just days.
We decided to take her home and let her decide when she was ready to leave us.
You never get used to the fact that your child is dying.
It never becomes normal.
We are lucky enough to have two older daughters and our whole family pulled together to support them, my partner Dave and I.
But it is impossible to get used to the idea that your baby girl won’t make her first birthday.
I used to talk to her and say: “They have it all wrong, you are not going anywhere” because I couldn’t believe it would happen.
I used to sleep with her on my tummy because I was scared she may die in her sleep and I wouldn’t be there for her when she needed me most.
I never left her in a room unattended in case she stopped breathing.
During the six months that Lily was home, we realised just how little information there was available for families.
We searched for information on the internet and it felt like everything had been written for doctors by doctors –
not for parents who have just been told the devastating news that their child is going to die.
We also quickly realised that there was no support networks – we knew there were other parents like us out there but we didn’t know where they were or how to find them.
We decided that we were going to change this – that Lily’s short life would have a purpose – and in October 2007, just five months after Lily died, we created The Lily Foundation.
I gave up my job as a teacher to run the charity, which funds research, supports families and raises awareness of mitochondrial diseases.
The decision by the Human Fertilisation and Embryology Authority to allow clinics to apply for permission to help women give birth to babies with three genetic parents could help prevent a range of potentially fatal genetic conditions.
It is a great day for many families who are living with mitochondrial disease in the UK and I am delighted.
But our mission does not stop there.
We still need to find better treatment and, ultimately, a cure for mitochondrial disease and all of the families dealing with its effects.
For those affected, we – along with our amazing families and incredibly loyal supporters – will keep going until we get there.