IVF makes parents more likely to have a baby boy than a girl – and now we know why.
When IVF doctors choose one of several embryos to transfer for pregnancy, they are unintentionally selecting male embryos over female ones, scientists have found.
That is because embryos are chosen based on how well they are growing and developing, and male embryos grow slightly faster in the first few days after conception.
“When you equate faster with better, then what happens is you favourably select male embryos over female embryos,” said Dr Helen O’Neill, a fertility specialist at University College London.
“The tools we’re using are selecting males,” added Dr O’Neill, who led the research and presented it at New Scientist Live, a public science festival in London.
With IVF, conception is in the lab (Photo: Abraham Gonzalez Fernandez/Getty)During IVF, sperm is added to several eggs in a dish, with the hope of making as many embryos as possible. After about five days, the embryo that looks the healthiest and seems to be growing the best is chosen for transfer into the woman’s womb.
Previous studies have found that IVF leads to a slightly higher chance of having a boy, with some kinds of fertility treatment resulting in 56 per cent of babies being male – but it was unclear why.
In theory, the explanation could have been that the process of growing embryos in a dish made male ones more likely to survive, said Dr O’Neill.
But the new study suggests the sex bias actually happens when embryos are selected for transfer.
AI used in IVF
Until recently, embryos have always been graded for quality by a doctor looking through a microscope and judging their appearance.
Now, fertility clinics also offer the use of AI for the grading process, based on time-lapse videos made as the embryos develop. They are not always used, though, as they cost extra and do not improve chances of pregnancy, according to the Human Fertilisation and Embryology Authority.
To investigate any impact on the sex ratio, Dr O’Neill’s team analysed how likely male or female embryos were to be chosen by either doctors or one of two different AI systems. They tested all three on 1,300 embryos where the sex was known through genetic testing.
When doctors did the selection, they rated 69 per cent of male embryos as good quality, compared with only 57 per cent of female embryos.
An AI programme called KIDScore D3 also had a slight sex bias towards boys. This system gives each embryo a quality score from 1 to 5, with male embryos getting an average score of 4.18 compared with 4.02 for females.
But a spokesperson for Vitrolife Group, which markets KIDScore D3, said the study findings were erroneous. “KIDScore D3 has been in use for many years, and if such a bias was inherent, it would be likely that other reports of live birth sex bias rates would have been reported,” she said.
The other AI system, called Chloe EQ, rated male and female embryos about the same. Fairtility, the firm behind Chloe EQ, was approached for comment.
The Chloe EQ system may avoid bias because it was designed to “learn” to choose embryos that are most likely to lead to a successful birth, based on previous embryos used in IVF, said Dr O’Neill.
Male embryos develop faster in their first few days of life, because female ones have to deactivate one of their two X chromosomes. This is a crucial mechanism for genetic balancing, but it takes energy and resources.
However, male embryos have one X and one Y, and so do not need to shut down any chromosomes.
The difference in development speed could not be used to deliberately choose male or female embryos, because it is so small. “While sex differences in grades exist, grades cannot be used to reliably infer embryo sex for individual embryos,” Dr O’Neill’s team say in a paper that has been submitted for publication but has not yet been peer reviewed.
Also, sex selection during IVF is not allowed at UK fertility clinics, unless the parents have a genetic medical condition that affects only one sex.
Hence then, the article about why ivf raises the chance of having a baby boy was published today ( ) and is available on inews ( Middle East ) The editorial team at PressBee has edited and verified it, and it may have been modified, fully republished, or quoted. You can read and follow the updates of this news or article from its original source.
Read More Details
Finally We wish PressBee provided you with enough information of ( Why IVF raises the chance of having a baby boy )
Also on site :