Viewpoints: What does the future of IVF look like?
As the government gives the green light to an IVF technique using DNA from three people, which could eliminate some diseases passed from mother to child, the world top fertility experts gather in London to discuss the latest advances in reproductive medicine.
What are the potential future developments for in vitro fertilisation (IVF) - and what kinds of ethical dilemmas do they raise? We asked a range of people for their views.
Josephine Quintavalle, founder, Comment on Reproductive Ethics
"IVF is better when it acts as a fertility treatment which tries to imitate nature.
This means minimal stimulation, not using large doses of drugs, and using good eggs but not multiple eggs from each woman's cycle, as they do in Scandinavia.
We need to go back to the original concept of IVF and not try to distort nature.
Journals are now seriously analysing the physical repercussions of using some of the drugs. They've looked at the health of the offspring of naturally-conceived and IVF twins - and nature wins.
Three-person IVF - to prevent the transmission of inherited DNA disorders - is highly experimental and a distorted form of the natural process.
A healthy embryo is sacrificed to make a healthy child, and we would need to follow one of these children through to their reproductive stage to see what the consequences of this technique are.
The technique might save 10 lives a year - but how many embryos are destroyed in the process?
You haven't cured a disease if you've eliminated somebody.
There are huge international concerns about the UK's stance on this because it's genetic modification of a human being.
IVF has given people the idea that you buy into something, a product. Inevitably, choosing the sex of your child will happen.
Then we'll move towards creating the perfect child very quickly.
Dr Dagan Wells, senior leadership fellow in reproductive genetics, University of Oxford
"IVF is a hugely successful medical intervention - but it's still relatively inefficient. Two-thirds of IVF cycles don't result in a baby.
We now know that having the right number of chromosomes is the biggest factor in a successful embryo transfer.
In my lab, we're now using a new genome sequencing technology to count the chromosomes in embryos, which we hope will be more cost-effective than existing methods.
Pre-implantation genetic screening like this has been around since 1993 and a new generation of technologies seem to be working well.
In fact, trials show that there is a significant advantage to having chromosomes screened before implanting the embryo.
If we can transfer a single embryo which has gone through chromosome screening, we can reduce the risk of abnormalities in children and cut down the number of IVF cycles needed.
Yet it's used in only 1% of IVF cycles in the UK, compared to 15% of them in the US.
Even when the 'perfect embryo' is transferred into the woman there is still no guarantee of a baby - only a 75% success rate.
We're trying to find out what other factors are at play here.
Hopefully in the next year or two this research will lead to tests which will guide doctors to embryos which have an excellent chance of success.
For me, this does not raise ethical concerns because these tests are not used to select a trait or a characteristic - they are simply testing for the ability to be alive.
There are more than a million embryos preserved in freezers around the world, but less than half of them have any chance of making a baby.
Susan Seenan, deputy chief executive, Infertility Network UK
Women don't have a right to have a child, but they do have the right to try for one, and IVF has given a lot of couples the chance to have a child of their own.
Infertility is a huge issue for many women. When you can't have a baby you feel as if there is something wrong with you - and there is.
It's is a medical condition. People don't choose to be infertile.
Embryo screening has been one of the most important medical advances. If you put back the best quality embryo then the chances of having a healthy pregnancy are increased. A single healthy pregnancy produces the best outcomes.
But there's no guarantee that IVF will work for everyone and we've got to keep getting that message across.
Some people still think, particularly if they are trying to conceive later, that they will be able to fall back on IVF.
The biggest issue, however, is about access to NHS treatment. NICE looked at all the evidence and decided that women under 40 should have access to three full cycles of IVF on the NHS, but these recommendations are not being followed in all parts of the UK.
Some clinical commissioning groups are not funding IVF at all while others are basing their funding decisions on different social criteria because they don't believe it's a medical priority.
This is fundamentally wrong and very unfair.
Dr Allan Pacey, senior lecturer in andrology, University of Sheffield
Intra-cytoplasmic sperm injection (ICSI) has really revolutionised the treatment of male fertility in the past decade.
Within the next 10 years or so, I think we will be able to make sperm for men.
This will be particularly important for young boys who have cancer treatment because if they are under the age of 13 when they have cancer, they are likely to be sub-fertile afterwards.
We're closer than we've ever been to making sperm for them in the lab - and we can do it in a number of ways.
For a boy with cancer, before his treatment, we can take some stem cells from his testicles (which become sperm during puberty) and freeze them. When he has recovered we can reinject him with the cells and get him to make sperm himself or we could do it in the lab.
Alternatively, we could take a cell from someone's cheek and reprogram it to make some sperm. Then they could have a genetic child.
At the moment, this is all theoretical but some of these steps have worked in animal models and it's only a matter of time.
Ethically, it's no more contentious than doing a transplant, but making sperm in the lab might be seen as more contentious. However, there's nothing that says we can't change the law.
It's good and healthy that we're having these discussions now in the UK. If we start talking about the possibilities now then we'll be ready to make the right decisions when the we know the science works.
Half of all fertility problems in couples are down to men, but men tend to think it's the woman's problem.
We need to go into schools and universities and talk to young people about male infertility before they suffer from it themselves.
Every new cohort of men think they are unique, but they aren't.
Hugh Whittall, director of the Nuffield Council on Bioethics
It's our job to get issues, like three-person IVF, on the table and encourage healthy discussion.
These discussions aren't just for scientists or philosophers - we bring together people from medicine, law and ethics, and then we invite opinions from patients, professionals and academics too.
We published our report on new techniques that aim to prevent the transmission of maternally-inherited mitochondrial DNA disorders 12 months ago and concluded that it would be ethical to offer this technique to families who suffer from serious disorders.
We looked at the issues of identity, parentage and the fact it is a germ line therapy, but we thought it would not lead to 'a slippery slope'.
However it's important that we proceed carefully, that this technique is carried out within a licensed, regulated environment and that there is long-term follow up.
IVF, when it started, was about treating infertility, but there have been significant changes since then. With the help of pre-implantation genetic diagnoses, it can enable children to avoid getting really serious diseases.
The council was set up over 20 years ago because people realised that what was happening in genetics needed an ethical perspective.
As science advances, it challenges us. Some say science is moving faster than ethics, but I think science is quite sensitised to it.
There are some people who will never agree about the use of embryos, but the key thing is not to stop bringing them together.
Prof Charles Kingsland, clinical director, The Hewitt Fertility Centre in Liverpool
For a variety of reasons, around one in six couples has infertility issues now.
Women are having children later in life - the average age for women to have their first baby is 31, men's sperm count is dropping, sexually transmitted diseases are increasing and we're getting fatter.
Maybe evolution will occur so that women will naturally be able to have babies later in life but, at present, biology hasn't caught up with society.
Is it right to get older women pregnant? We can do it - but should we? These are not just medical issues.
These are not questions which doctors can answer on their own. We rely on a lot of debate before we believe it is right to use these techniques.
Reproductive medical technology will always be high profile because we are pushing back the frontiers of medical science, and the public needs time to understand and form an opinion when confronted with new techniques.
In three-person IVF all you're doing is replacing the worn-out bit of the egg, just like changing the batteries.
The key element in all IVF techniques is having a healthy embryo.
There are many ways of assessing the viability of embryos and the most recent one, using a video camera in an incubator full of embryos, means we can look at them every five minutes to check how they are developing and growing.
Before, we could only examine them once a day when we took them out.
In the last few years, scientists have learnt how to freeze women's eggs, so in future there will be egg banks as well as sperm banks.