IVF clinics claim a better success rate than nature

The birth of Britain's first "test-tube" baby 23 years ago was a revolutionary medical breakthrough but the in-vitro fertilisation technique that brought that first baby, Louise Brown, into the world has become so successful that couples now have a better chance of conceiving using the method than by having sex, according to some scientists.

Since Louise's birth, thousands of children have been conceived outside their mother's womb, by the laboratory procedure that fertilises the egg, allows the embryo to grow for five days and then implants it in the womb.

Now, several fertility clinics are claiming they can produce higher pregnancy rates for each implantation "cycle" than by sex. The 36 per cent success rate for IVF compares to 25 per cent for the average couple, according to an Australian clinic.

However, a leading British doctor said that, although IVF had come a long way since 1978, such statistics should be treated with caution. Dr Paul Rainsbury of the Bupa Roding Hospital in London, said: "A rate of 40 per cent of pregnancies is achievable after the embryo is implanted but a lot can happen between being pregnant and delivering a baby."

IVF often has higher rates of miscarriage, ectopic pregnancies (outside the womb), and early pregnancy loss than pregnancy through sex, he noted.

Because multiple embryos are implanted, it also has a higher rate of multiple births, such as twins and triplets.

An Australian clinic, Reproductive Medicine Albury, in New South Wales told New Scientist magazine it achieved the pregnancy rate of 36 per cent for each attempt by improving the temperature control and acidity of the specified environment and providing a better growth medium while the new embryo was developing.

Keith Harrison, scientific director of the Queensland Fertility Group in Brisbane, said: "There's now substantial evidence that the good results achieved by these tweaks can be duplicated. All clinics should be adopting them."

In Britain, the Government insists IVF clinics can only advertise their "live birth" percentage – the number of children born per 100 treatment cycles – but some clinics can skew the numbers by concentrating on women younger than 30 or excluding couples where the man has a low sperm count, thereby cutting out a lot of people who have a low chance of success, said Dr Rainsbury. IVF success rates were currently on a plateau, he said.

"The first IVF baby, Louise Brown, was a huge breakthrough," Dr Rainsbury said. "The next major change came from Brussels, where they developed ICSI – intra cytoplasmic sperm injection, where a single sperm is injected into the egg to fertilise it. That was licensed in the UK in 1993 for couples where the man has a very low sperm count.

"But what's waiting to happen is an understanding of implantation. We don't know why we can implant two embryos into an apparently healthy 20-year-old and get nothing, yet implant two more into a 40-year-old and see it work.

"We still don't understand the mechanism of implantation, and whoever cracks it will probably get a Nobel prize – and deserve it," he said.

However, sex still has the advantage that it doesn't usually cost £5,000 to £10,000. Even Mr Harrison agreed: "IVF is expensive and intrusive," he said. "I think most people are going to continue getting pregnant by bonking in the suburbs, rather than coming to us."