A British woman has become the first in the world to give birth using a new IVF test that promises to improve the chances of parenthood for infertile couples.
A boy, named Oliver, was born in July to a 41-year-old woman who had tried 13 cycles of IVF without success. She conceived after her eggs were screened to select those that were the most viable.
The screening technique has the potential to raise IVF success rates significantly, particularly for women in their late 30s and 40s and couples with a history of failed fertility treatment or miscarriage. It could also be used in younger women to promote the use of a single embryo in IVF to guard against risky multiple births. If the test can pick the best eggs, one embryo could be transferred to the womb without reducing success rates.
Simon Fishel, managing director of the CARE Fertility Group in Nottingham, who treated the new parents, said: “Oliver’s birth is an important landmark in shaping our understanding of why many women fail to become pregnant.”
He said that older versions of the screening test have been shown to double the chances of IVF success for some couples with a poor prognosis, and that early results suggest that the new technique is at least as good, if not better.
Since the pregnancy that led to Oliver’s birth was announced in January, about five more women have conceived after taking the egg test, known as Array Comparative Genomic Hybridisation (Array CGH), out of about 20 treated.
All the patients treated had a poor prognosis, with multiple failed attempts at IVF, and Dr Fishel said that the early success rate of about 25 per cent was a considerable improvement. “I’d generally give these women about a 10 per cent chance of getting pregnant,” he said.
The effectiveness of Array CGH, however, has yet to be assessed in a randomised controlled trial — the gold standard for medical therapies — and other scientists were more cautious about its prospects. Several other quality tests for eggs and embryos have looked promising at first, but have been found wanting by randomised trials.
Tony Rutherford, chairman of the British Fertility Society, welcomed the birth, but added: “It is absolutely essential that these new techniques are subject to further rigorous research; and should only be offered to patients within the context of a robustly designed clinical trial, carried out in suitably experienced centres.
"The widespread use of this technology should await the outcome of such research to ensure we know which patients might benefit. All too often we see ground-breaking news about techniques that seem to offer great hope, but fail to live up to expectations when applied in widespread clinical practice.”
Array CGH seeks to identify eggs that have the wrong number of chromosomes, which will generally fail to develop properly if fertilised with sperm. Such chromosomal abnormalities are difficult to detect in eggs or embryos by eye, and they are among the major causes of IVF failure.
Array CGH has two main advantages over other methods of screening: the first is “gene chip” technology that tests DNA very quickly, so that eggs or embryos do not need to be frozen while they are checked. The second is that instead of removing cells from embryos, which can damage them, it relies on testing the eggs, which are the cause of 85 per cent of chromosomal defects.
Healthy human cells have 46 chromosomes, 23 inherited from each parent. Before an egg is fertilised, it ejects half of its complement to leave space for the 23 paternal chromosomes carried by the sperm. The waste chromosomes are jettisoned in a structure called the polar body and are a mirror image of those left behind in the egg.
Array CGH checks that an egg’s polar body has 23 chromosomes: if it does not, its parent egg must have too many or too few. Doctors can then ensure that only normal eggs are fertilised to produce viable embryos for transfer to the womb.
Oliver’s mother produced eight eggs, of which only two were found to be normal and transferred to the womb. In several other cases Dr Fishel’s team has found no eggs suitable for transfer.
The test costs £1,950, on top of the £3,000 or so for IVF. It is not available on the NHS or at other private clinics.
Professor Peter Braude, of King’s College London, said: “I am delighted that this patient has achieved her positive outcome after so many years of trying. However we need to be cautious as to whether the new technique was responsible.
“I hope that this is not the case here and would love to see a positive outcome to rigorous analysis of this technique, but at the moment this can only be viewed as a potentially very lucky result.”
