Genetic screening can prevent miscarriage

HALF of miscarriages in women over the age of 38 may be prevented using new screening technology, according to leading UK fertility experts.

Pre-implantation Genetic Screening, or PGS, is a powerful way of selecting embryos during IVF and has been proven to secure a high chance of pregnancy, continuing to live birth.

And lead embryologist Bert Stewart, from Cheshire-based Reproductive Health Group, says PGS should be more routinely used, preventing “wasted time, money and heartache” for older women looking to have children.

PGS allows fertility experts to look at a woman’s individual embryos, and the number of chromosomes within those embryos.

During traditional assessment, any abnormalities are invisible and routine exams do not reveal which embryos are ‘normal’.

Age is closely linked to abnormalities, with women aged 37 likely to have abnormalities in 50 per cent of their embryos. After 37, the rate continues to rise.

Mr Stewart says: “PGS gives a much more black or white result on each individual embryo.

“Essentially, the technique allows us to look at the number of chromosomes within the cells of the embryo. A normal human embryo should contain 46 chromosomes, neatly arranged in matching pairs.

“We know that in the final maturation process of many eggs, mistakes are made in the sorting out of which chromosomes are thrown out by the egg and which ones it will keep to pair up with those from the fertilising sperm.

“This can lead to eggs with missing or extra chromosomes.

“With very few exceptions, an embryo with the wrong number of chromosomes will not produce a baby.

“Most abnormal embryos either fail to implant in the uterus or miscarry during pregnancy.”

While embryos that stop developing very early during the IVF culture are easy to spot, many can still develop seemingly quite normally.

Mr Stewart continues: “Of course, if they do this we are likely to want to select them for embryo transfer or freeze them for future use. The problem is, most of these will at some point stop developing.

“This could lead to a positive pregnancy, even a viable fetus on early pregnancy scan, but a pregnancy that is most likely to end in heartbreaking miscarriage.”

PGS involves removing a few cells from blastocyst stage embryos and checking chromosome numbers.

Mr Stewart says PSG is the ‘way forward’ to potentially improve IVF success rates, and to cut the number of transfer that eventually lead to miscarriage for women in their late thirties and early forties.

He said: “The risk of having an embryo with the wrong number of chromosomes is greatly affected by the age of the mother. For women in their early thirties, about one quarter of their eggs and embryos will have the wrong number of chromosomes.

“For women in their forties, it is more likely that more than half of their embryos will be abnormal.

“So half of all miscarriages in that advanced age group may be prevented by screening.

“It saves wasted time, money and heartache, especially for women that have gone through miscarriage time and time again and have found that very hard to take.

“You can still do IVF without doing any of this. But, understandably, some people want to be more certain.

“Whilst it does not guarantee pregnancy, chromosomally normal embryos are more likely to implant than unscreened embryos, and more likely to go all the way to the most desirable outcome of any treatment, a healthy baby.”

PGS is tightly regulated by the Human Fertilisation Embryology Authority.

Data from Reprogenetics suggests that results are accurate for over 95% of screened embryos and the risks of an IVF cycle using PGS are no different from those of a typical IVF cycle.

“The important thing to get across is that an embryo is what it is,” Mr Stewart says. “We are not changing it in any way. We are just checking it.”

At Reproductive Health, experts offer Next Generation Sequencing, which is highly accurate, efficient, and comes at a relatively low cost.

Mr Stewart says: “The technology is getting more and more effective, and more accurate. Each new generation tends to be able to do more for much less.

“I can see in the next few years PGS might become routine and this should become more accessible for all IVF patients.”

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