The 32-year-old human resources officer, who lives in Leith, was over the moon when she discovered she was pregnant after three years of trying, but a scan revealed not only that her pregnancy was abnormal but was in fact a cancerous growth.
Doctors diagnosed a molar pregnancy, a rare condition where an inviable egg is fertilised and develops like a skin growth, and in extremely rare circumstances can become cancerous.
The recovery rate is 99 per cent and most women go on to have children after treatment, but for Helen it was a completely different story.
"After my 12-week scan I was taken straight into surgery to have the growth removed," said Helen.
"I then had to endure a nine-month course of chemotherapy, but all the way through the doctors were telling me how good my chances were.
"They told me that I would go on to have children, and even showed me a baby book featuring mothers who had recovered from a molar pregnancy with their children.
"The chemo was the hardest thing I had ever had to endure but one of things that got me through it was the thought that I would be able to have children at the end."
The chemotherapy ended in December 2006 and Helen was able to spend a happy Christmas with her husband Richard, 34, at their home in Ipswich. But the New Year brought a final devastating blow that ended her hopes for motherhood forever.
"I was told that the chemotherapy hadn't been successful and I was given a choice to either undergo more chemo or have a hysterectomy," added Helen.
"The first round of chemo was so horrific that I didn't think I could go through it all again, but I didn't even want to consider the other option.
"The doctors went away to give me time to decide what to do, but then they came back a few hours later and took the decision out of my hands.
"They told me that I had to have the hysterectomy."
After the operation Helen declined the offer of counselling and returned to work after a month, going against doctors' advice that she should take at least three months off and preferring to rely on her husband and family for solace.
However, she soon found the pressure too hard to bear and, after nine months travelling in Australia and New Zealand, she decided to start a new life with her husband in Edinburgh two years ago.
This weekend, she is set to run the Bupa Great Edinburgh Run for cancer research.
She said: "We're finally starting to feel optimistic about life again, which is why we've decided to start campaigning for cancer research.
"We're raising money for the Cancer Treatment & Research Trust (CTRT), which works closely with the UK specialist centre for molar pregnancies at Charing Cross Hospital in London where I received my treatment."
Helen and Richard are trying to raise 100,000 for a new CTRT research student. To sponsor her visit www.justgiving.com/Helen-Sherwood