LEAGUE tables listing the success rates of IVF clinics are encouraging bad practices such as implanting too many embryos, doctors have told 快猫短视频.
Multiple pregnancies are more dangerous for both mothers and babies, and improvements in IVF techniques mean it鈥檚 no longer necessary to implant several embryos to give a good chance of pregnancy. Yet at least half of clinics aren鈥檛 very good at IVF, says Jacques Cohen, director of the Institute for Reproductive Medicine and Science of Saint Barnabas in New Jersey, so many boost their position in the tables published in the US and Britain by implanting more embryos.
鈥淭he survival of clinics is at stake,鈥� says Cohen. 鈥淭he system doesn鈥檛 penalise multiple pregnancies.鈥� He and others say clinics should be ranked by live births per embryo implanted instead of by live births per treatment, which may involve implanting several embryos.
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In the US, the Centers for Disease Control is responsible for the annual figures, while in Britain they come from the Human Fertilisation and Embryology Authority (HFEA). Both agencies say that their figures are not meant to be a ranking system. But that is exactly how most would-be parents view them. Details about the rate of multiple births at clinics aren鈥檛 given much prominence.
Doctors have told 快猫短视频 that the pressure to achieve a high ranking is driving clinics to select younger patients with a higher chance of getting pregnant, to implant more embryos than necessary, and even to recommend IVF to women who don鈥檛 need it. The result is that over half the babies born by IVF come from some sort of multiple pregnancy. 鈥淲e have moved from the age of the multiple baby to the age of the litter,鈥� Hossam Abdalla, director of the Lister Fertility Clinic in London, told a recent conference in Montreal.
In Britain, the HFEA now recommends that no more than two embryos should be implanted in most cases. 鈥淏ut not a lot of us follow that,鈥� Abdalla says. 鈥淚f you want to do well in the tables, you put in more embryos.鈥� In the US, where guidelines are laxer, a whopping 71 per cent of transfers involve three or more embryos, he adds.
鈥淭here is a pressure to implant more than two, but we could take their licence away,鈥� responds Ann Furedi of the HFEA. 鈥淚 find it difficult to believe that anything other than a small minority of clinics would ignore the guidelines.鈥� Yet she admits that the HFEA does not even know how many clinics transfer more than two embryos.
Multiple pregnancies are bad for both mothers and babies. The mothers are more likely to suffer from complications such as high blood pressure, haemorrhages and pre-eclampsia. The babies are more likely to be premature, to have birth defects and neurological problems such as cerebral palsy, and to have a low birthweight, which brings health risks in the short and long term. Studies also suggest that substance abuse, violence and divorce are more common among parents of multiple-birth children.
An increasing number of experts believe that implanting just one embryo gives a perfectly good chance of achieving a pregnancy, thanks to major improvements in IVF techniques. For example, at least half of the embryos created by in vitro fertilisation are abnormal, says Cohen. Researchers are working on ways to weed out these defective embryos, such as assessing the shape of the embryos and doing pre-implantation genetic analysis.
But these techniques are expensive, and not all patients can afford them. However, there are other, less expensive measures that can be taken, such as better use of microscopes, says Cohen. Some clinics examine embryos at too weak a magnification and miss problems, for example. Many clinics are aware of issues like this, he says, but are too understaffed to do anything about it.
Swedish fertility expert Lars Hamberger says that the success rate for single-embryo transfers in women under 37 is excellent 鈥� about 35 to 40 per cent. And even for older women, who have a much lower chances of success, Hamberger says that weeding out abnormal embryos and then doing pre-implantation tests should make a big difference.
Yet unless the statistics are presented differently, the clinics won鈥檛 have any motivation to reduce the number of embryos they implant, say Cohen and Abdalla. One idea is to display a clinic鈥檚 rate of multiple births per clinic prominently next to its live birth rates, so that patients can see whether a clinic鈥檚 鈥渟uccess鈥� is due to transferring several embryos. Even better, Cohen suggests, tables should present the birth rate per embryo transferred.
But regulators are not convinced. 鈥淚鈥檓 not really sure that would make it any clearer to the people it really matters to,鈥� says Furedi of the HFEA. And Sean Tipton of the American Society for Reproductive Medicine adds: 鈥淔or the consumer, the live birth rate per cycle is the most meaningful [figure].鈥�
There鈥檚 also resistance from would-be parents, says Furedi: 鈥淔or some patients, having twins is an instant family.鈥� Gedis Grudzinskas of the Bridge Centre in London says that while many clinics try to follow the HFEA鈥檚 guidelines, some are giving in to would-be parents鈥� demands for more embryos.