Louise Brown was the first person in the world to be born through the method of In Vitro Fertilisation (IVF).
In 1978, her birth triggered global opinions and debate surrounding ethics of the procedure.
However, the breakthrough inspired millions to hope for the first time that they too may become parents using the advance in technology.
"Today is my 40th birthday. Like most people, I would probably rather keep that fact to myself," she wrote for the Independent.
"But, around the world, the celebration of my birthday will also see celebrations that mark the 40th anniversary of IVF – the procedure that led to my birth."
"New research released last month claims there have been eight million people born through IVF since its invention. An exhibition at the Science Museum, London, talks of six million – nobody is really sure of the exact numbers as there are babies being born every day now through assisted reproductive techniques," she said.
Louise explains how Patrick Steptoe and Robert Edwards, the two men responsible for the technique wanted her middle name to be Joy, as her successful birth meant hope for people worldwide and with babies comes joy.
"Forty years, and millions of babies later, many will agree they were right," she added.
As the decades have gone on, Louise points out that so many things have changed but the desire for couples to have a child has not wavered.
She continues with how her own parents stumbled upon the treatment.
Her mother Lesley Brown was suffering from depression, Louise points to being childless as a large factor.
Upon hearing of the experiment, Lesley and her father John had "something to cling on to."
It led to Louise's incredible birth and then her sister's Natalie being born in 1982, marking the 40th baby to be born worldwide via IVF.
"That same journey is there for couples today and thanks to the pioneers the road is easier to travel than ever," Louise continued.
Penning her birthday account for the Independent, she highlights the debates around the success rates of different techniques that stemmed from that break through and how difficult infertility remains for couples.
"Heartbreakingly things don’t work out for everyone. The moral debate about how far science should go in genetics rages on. IVF is now a multi-billion pound worldwide industry and it depends on where you live as to what help is available – and at what cost."
"Every day women and men start out on this journey. First, they have to pluck up the courage to say things aren’t working for them in the most intimate part of their lives. They must share their troubles with doctors and specialists. Some hide it from their closest friends and family."