A gay couple has welcomed a set of twins with two different fathers, after both men were able to fertilise an embryo during the IVF process.

Calder and Alexandra Berney Edwards are actually half siblings despite being born at the same time, because they don't share paternity.

They were born to London-based couple Simon and Graeme via surrogate, Meg Stone, 32, whom they met in Canada.

Amazing advances in IVF meant that the couple were able to fertilise an embryo each and both were placed into surrogate Meg Stone's womb.

Simon (right) and Graeme Berney Edwards are both biological fathers to their twins Calder and Alexandra (seen shortly after their birth) after they were both able to fertitilise an embryo

Simon, 43, said: 'It really is amazing that Graeme and I have been able to father one of our twins each.

'Meg did an amazing job - and it meant that she was actually pregnant by two men at the same time. It's thanks to the wonder of IVF that we have been able to achieve our dream.

'Graeme and I have always wanted to have a family, and now we have our lovely twins.

'They are still classed as twins even though they have different biological fathers.'

The couple knew that they wanted to try to start a family this way as it meant that they would be the named parents on the birth certificate from the start.

Amazing advances in IVF meant that the couple were able to fertilise an embryo each and both were placed into surrogate Meg Stone's womb. Pictured: Meg with twins

The couple travelled to Canada in order to have the IVF they required, as the process of fertlising two embryos with different sperm isn't yet available in the UK. Pictured: Graeme and Simon with the twins

This is unlike the UK where it can take up to six months to get a parental order granted to change it from the named birth mother at the birth.

This treatment isn't practised in the UK, where two embryos fertilised by different fathers are put back at the same time.

So they extended their search for a surrogate to Canada and met Meg who already had a family of her own - her two sons, Jeffrey, 12, and Max, five.

Meg said: 'I saw Simon and Graeme's profile on a surrogacy website and I thought they had lovely smiles.

The married couple say that meeting Meg was like being 'reunited with a long lost sister'

The twins have just celebrated their first birthday and Meg flew over from Canada to help them celebrate

'I had recently split with my partner and I wasn't ready for another baby, so I wanted to help someone.'

The couple chose an anonymous egg donor, and then flew out to a fertility clinic in Los Angeles to fertilise the embryos.

Simon said: 'We couldn't decide on who would be the biological father. Graeme said it should be me, but I said that he had just as much right as I did.

'When we spoke to the doctor at the clinic he stunned us with his reply. He told us that it could be both of us.

'They said that we could have half the embryos fertilised with my sperm and then half with Graeme's sperm.'

The couple then tied the knot, and decided to fly out to Canada on their honeymoon - and meet up with Meg for the first time at the same time.

Simon said: 'We were nervous at the beginning - in case that we didn't click with her. But we needn't have worried.

The couple now refer to Meg as the twins' 'Tummy Mummy' which she says she loves

The couple say that their two children have gone from strength to strength and are 'hitting all their milestones'

'Meeting Meg was like being reunited with a long lost sister. She wrapped us both in a hug before introducing us to her adorable boys.

'We didn't how to thank her. We told her we were so grateful to her - she was changing not only our lives but our families too.'

Six months later, one fertilised embryo of Simon's, and one embryo of Graeme's were put back into Meg's womb.

Then they faced an agonising two week wait to see what would happen and whether it would work.

The couple risked only one of the embryos working, which would mean that just one of them would be the biological father to the baby.

Simon said: 'We talked about it and decided that if it happened, we would just go back and have another go again, so that we would end up fathering one baby each.

HOW DOES IVF WORK? The menstrual cycle is first suppressed with medication before other drugs are used to encourage the ovaries to produce more eggs than usual. An ultrasound scan is carried out to check the development of the eggs, and medication is used to help them mature. The eggs are then collected by a needle inserted into the ovaries, via the vagina, before the eggs are fertilised with sperm. Finally the fertilised embryo is transferred into the womb to grow and develop. A single IVF cycle has an average success rate of 32.3 per cent for those under 35, dropping to five per cent for women aged 43 and 44 and only 1.9 per cent for those 45 and older. Despite IVF being most effective for the under 35s, 57 per cent of IVF cycles are undergone by women 35 or older. Advertisement

'When the two weeks were up, Meg had some fantastic news - she was pregnant. It had worked.

'Now we just had to wait and see if she was pregnant with both of our babies - or just one.'

Meg had an early scan a few weeks later and it was a nerve-wracking wait. Even if both the embryos had taken, it may be that only one of them had gone on to survive.

But against all odds it had worked and Meg was pregnant with both babies.

Simon said: 'She FaceTimed us from the scanning room. First of all we saw one heartbeat, and our stomach clenched with nerves.

'Then we saw the other heartbeat. Graeme and I just hugged each other. We were just over the moon. We were both going to be dads - she was pregnant with both of our babies.

'We kept in touch with Meg regularly and she gave us updates on how the pregnancy was going.

'And we went over to Canada to visit her for her 19 week scan. We put our hands on her bump and felt our babies kicking. It was a magical moment.

'For our Christmas present, she had arranged a lovely photoshoot to be done with all of us together. We got to meet her family too, which was lovely. It was great to see her being a mum to her children. We knew that our babies were in the best possible hands.'

The pregnancy went smoothly but at 31 weeks, pregnant in May last year, Meg sent messages to say that she was in pain and thought she was in labour.

Simon said: 'We were panicking as she was five weeks early. We didn't know whether we would make it to the birth.

'We packed our stuff and caught the first flight out to Canada. But whilst we were in the air we couldn't contact Meg to find out what was happening. The wait was agonising.

'We dashed to the hospital when we arrived, to find out it was a false alarm. We were just so relieved that she and the babies were fine.

'We stayed out there and at 36 weeks, Meg went into labour. Graeme held her hand through it all whilst her mum and I stood at the other end.

'It was the most amazing experience of our lives. Alexandra was born first and then Calder arrived minutes later. They were both healthy and it was just amazing to meet them at last.

'When we both held them for the first time, we couldn't believe that we were both daddies. It was a long way to go and do this, but it was worth it to both be able to have fathered one of the twins each.

'Calder was the double of Graeme, and Alexandra was the image of me.'

'We were finally allowed to fly home with them seven weeks later. It was sad to say goodbye to Meg, When we brought them home for the first time, it was just incredible. Since then they have gone from strength to strength. They are doing so well and hitting all their milestones.

'We have had wonderful support too from TAMBA, the UK twins and multiple births association, which has been amazing.'

The twins have just celebrated their first birthday and Meg flew over from Canada to help them celebrate.

Simon added: 'It was incredibly special having her there to celebrate the twins special day with us. It's hard work having two babies, but Graeme and I are loving every minute of it.

'We are still in touch regularly with Meg, and we can't thank her enough for what she has done for us. It's amazing to think that she has enabled us both to become daddies. It's a wonderful gift.

Meg said: 'Simon and Graeme are like brothers to me now. They call me the twins 'Tummy Mummy' which I love.

'It was amazing being pregnant with embryos that they had both fathered - science is an amazing thing.'