IF Mark Harper can ever meet the man who made his dreams come true he would probably cry.

Then the 33-year-old would shake his hand a thousand times and thank him for changing his life forever by making him a dad.

"All I ever wanted is a family," said Mark, from Ilkeston. "And this man, who I hardly know anything about, has made it happen for me. He's done something truly wonderful."

Mark's wife, Suzanne, 32, has just given birth to a baby daughter – but husband Mark is not Libby's biological father.

The pair used sperm donated from a young man in America to help them have their family.

After treatment to beat testicular cancer at the age of 21 and then fighting the disease for a second time in 2005, Mark was left infertile.

The couple were forced to turn to specialist fertility treatment and sperm donation to give them the family they desperately wished for.

But because of a huge shortage of sperm donors in the UK, the pair had to pay for their samples to be flown in from 3,000 miles away in America.

"We had no choice but to do it this way," said Mark, a construction foreman. "It cost us more than £600 each time but we were desperate to have a baby and my sperm count was zero.

"After testicular cancer, my sperm was totally annihilated. I'd had to have both of my testicles removed. There was no way I was ever going to father my own child.

"It was a devastating blow but our options became very limited. We either used donor sperm, adopted a child or lived our life without having a family.

"I knew how much Suzanne wanted her own baby and I wanted that too so we talked about using donor sperm. Even thought I couldn't be the biological father, I really wanted Suzanne to become a mum.

"For me, it was the next best thing. We didn't come to a quick decision, but I know it was the right one."

Since laws changed in April 2005, there has been a serious shortage of sperm and egg donors in the UK.

Men and women have been reluctant to donate because the new legislation means that children born from donation can now be given identifying information about their donor.

Although the donor has no parental rights over the child and is not bound by any financial commitment, fertility clinics have struggled to get donors to come forward.

"We feel very lucky to have been able to get a sperm donor," said Mark. "It came all the way from America, but at least it meant that we could try for a family."

In America, donors also do not have the right to anonymity, but despite that, sperm was more readily available, although since Suzanne and Mark went there for help, the law has changed again to ban sperm from abroad.

Mark said: "I'll never be able to thank the guy enough for what he had done for us. I've got no hang-ups about using a sperm donation.

"When I look at Libby, I might not be her biological father, but I'm her dad and I love her.

"I'll be the one changing her nappies and getting her bathed and dressed. I'll be bringing her up and loving her every day."

Mark and Suzanne were treated at CARE Fertility in Nottingham. The couple also needed specialist IVF treatment because doctors discovered that Suzanne's body was fighting against possible pregnancies.

Their eight cycles of treatment cost the couple a staggering £30,000.

Suzanne, who worked as a regional manager for a childcare company, explains: "Everything that could have worked against us did. We've had the most stressful time – in fact, that's an understatement.

"We've been trying for a baby since 2002. At times, it has been truly heartbreaking. We've been through so much.

"I think we've cried every day since having Libby. We hold her and look at her and then we cry. It's been a very emotional time for us.

"We've got the daughter we could only ever dream about. It's just wonderful. She means so much to us. There were times when I never thought we'd manage to have a baby.

"I can't find the words to say how I feel.

"Mark has been amazing throughout all this. What he's done is so wonderful. He loves Libby so much."

Mark and Suzanne met in 1995, but two years later Mark was diagnosed with cancer.

The slow-growing tumour was removed but, a decade later, cancer struck again. This time the tumour in his remaining testicle was aggressive and needed chemotherapy.

"At the time we didn't know that the testicular cancer would affect the quality of Mark's sperm," said Suzanne.

"But after we'd been trying for a baby for a while, we went to see my GP. Mark had a sperm test and it was revealed that his sperm count was zero.

"We were told that we'd need sperm donation and we went away to let the news sink in."

Mark and Suzanne initially started treatment on the NHS at the Royal Derby Hospital but soon transferred to CARE.

"We wanted a baby so much, but at that point we had no idea just how hard it was going to be."

They were told that a shortage of donors in the UK could hamper their chances.

But just before the Human Fertilisation and Embryology Association made changes to the law, medics shipped in sperm from America. The HFEA gave clinics in the UK special permission and a specific time slot in which they could source sperm from overseas. This offer has now ended which means infertile couples now face waiting for a match from the dwindling supply of sperm from UK donors.

"Getting sperm from American was good news for us," said Suzanne.

"We still weren't home and dry because, before you're allowed to have the sperm, you have to be a suitable match by the clinic.

"Thankfully CARE got in touch and said that characteristics had been matched and we'd be eligible for donor sperm.

"We knew nothing about the donor other than his eye colour, height, blood group, profession and hobbies."

It was last year, during their final cycle of treatment, that the pair finally struck lucky.

"We decided to have one last go," said Suzanne. "Emotionally we were getting to the end of the road.

"It was costing us a fortune but more than that it was really wearing us down. We were emotionally drained.

"We'd already made plans if it didn't work. We'd talked about leaving the UK and starting a new life abroad.

"We were going to sell the house and make some huge changes like that.

"We knew that if we weren't going to have children we had to take a different route in life."

But Suzanne and Mark didn't need to rethink their future.

Their final course of IVF treatment in March delivered a positive pregnancy result.

"I couldn't believe it," said Suzanne. "We'd pinned everything on this attempt, but that didn't mean it was going to work for us.

"We'd prayed in the past and it hadn't helped. But this time, it was just amazing.

"When I finally plucked up the courage and did a pregnancy test, I could see a faint blue line.

"I was absolutely stunned and ended up doing another just to confirm what I'd seen.

"I don't think I ever thought that I'd have a baby."

Suzanne's pregnancy was littered with complications and she spent huge chunks of her time going in and out of hospital. She ended up having 13 scans at the Royal Derby Hospital to check that the pregnancy was progressing well.

Finally, baby Libby was born on December 19, at 10.01am, weighing a healthy 6lbs.

"I can't believe that I'm finally a mum," beamed Suzanne. "There were times over the last few years when I thought we'd never become parents.

"We tried so hard and spent so much money on all this treatment – but it has been worth every penny.

"When I look at Libby I can't hide how proud I feel. She's been as good as gold and I'm loving every minute of it.

"I know Mark loves Libby as much as me. We're finally a family and I can't tell you what that feels like.

"We are the proudest parents."

Dr George Ndukwe, medical director at CARE Fertility Nottingham, said: "The whole team at CARE would like to send our very best wishes to Suzanne and Mark on the birth of Libby.

"This case highlights the importance of sperm donors without whom Suzanne's treatment would not have been possible."