YEARS of fertility trouble came to an end for Kerry Horan – when a doctor treated her with Viagra.

After three rounds of IVF and a miscarriage, the 34-year-old teacher and her husband David, 33, were beginning to give up hope.

But the drug, better known for its effect on men, became a key part of her treatment.

Despite problems with her womb lining and a higher than normal amount of natural “killer” cells which attacked her embryos, Kerry gave birth to medical miracle Grace in December.

She said: “The first time they mentioned Viagra I thought ‘Isn’t that for men?’ But they explained it increased blood flow and that can make the womb lining thicker.

“It was actually just part of a protocol of treatment they created.

“I was taking it around 10 days before the IVF started and it wasn’t pleasant, you could feel your face getting redder and warmer but eventually it settled down.”

Together since they were 18, Kerry and David married in 2002. They tried for a baby and were delighted when she became pregnant in 2005.

She said: “We went for the 12-week scan and they were told they couldn’t see a heartbeat. It was a nightmare. They confirmed I had miscarried a week later and the only thing I wanted was to be pregnant again.”

The couple attended Calderdale Royal Infirmary’s Assisted Conception Unit (ACU) but after 10 months nothing had happened and scans showed a thin womb lining.

They pursued private IVF treatments but received the “soul-destroying” blood test results that confirmed these too had been unsuccessful.

She said: “We decided to have a break and try to get on with life, and thought about adoption.

“Soon after I was reading a women’s magazine and one lady was describing how IVF had failed for her, she had problems with her womb lining and a poor blood flow and it all sounded very familiar.

“I did a bit of research and there was a guy at Care Fertility in Nottingham called George Ndukwe and we had a consultation.”

A series of tests revealed Kerry’s immune system was extremely strong, and elevated natural “killer” cells were attacking the embryos mistaking them for foreign invaders.

Alongside the IVF, steroids helped keep her aggressive cells in check, and crucially the Viagra helped Kerry’s blood flow.

She discovered she was pregnant on March 27, 2009.

She said: “The first time I went for the scan I was nervous but the first thing the nurse said was ‘there’s a heartbeat’ and I broke down in tears.

After years of trying proud dad David and Kerry became parents to 6lb 11oz Grace on December 3, 2009.

Kerry said: “We’re grateful to Calderdale Royal Infirmary ACU in Halifax and the maternity services and George and the Care team.

“It’s important to stress that the Viagra was used in conjunction with other drugs in a very targeted way, you become desperate when you want a child and it would be wrong for people to buy it on the internet and think it could help their fertility.

“Grace is a really good baby, she was born by Caesarian which is typical – all that effort to get her in there and then she doesn’t want to come out.”

Dr George Ndukwe, medical director of Care Fertility in Nottingham, said: “With Kerry’s history, I arranged for detailed tests to be done.

“These revealed a problem with her immune system and 3D scans showed the flow of blood to the womb was poor. For an embryo to implant successfully, it must connect to a rich blood supply.

“Viagra improves blood flow – for men. However, I have used this drug in a small group of women with poor uterine blood flow to improve their chances of pregnancy. It should only be used under medical supervision and it’s not a fix-all for anyone trying for a baby.”