A mother’s age may not be to blame for the high risk of genetic disorders in IVF babies born to older women, a new mouse study suggests.
Exposure to hormone therapy and embryo culture – when embryos are left to grow in a petri dish – appeared to have a powerful impact on the gene expression of mouse pups.
The mother’s age, the scientists found, had no impact at all on the baby’s gene expression.
The authors of the study, from the University of Pittsburgh, say their findings suggest something about the technology – not a woman’s age – is to blame for the high rate of babies born with disorders to older mothers who have undergone IVF.
For decades, scientists have noticed a trend that IVF babies born to older mothers are more likely to be born prematurely, have a lower birth weight, and birth defects
‘Women of advanced maternal age might have one less thing to worry about,’ said lead author Audrey Kindsfather, a medical student researcher at Pittsburgh’s Magee-Womens Research Institute.
‘We need clinical studies to back that up, but this is a promising animal model that clinical studies could be based on.’
Since the first IVF baby was born in England in 1978, more than 1 million US babies have been conceived using assisted reproductive technology.
According to a recent analysis by Penn Medicine, around 1 to 2 percent of US births every year are the result of IVF.
The technology has allowed women to conceive well beyond the scope of their own biology, but clinics routinely warn mothers to be wary about leaving it too late, even if they have the means to undergo multiple rounds.
For decades, scientists have noticed a trend that IVF babies born to older mothers are more likely to be born prematurely, have a lower birth weight, and birth defects.
Research earlier this year found that IVF technology itself does appear to leave a mark on several genes in all babies – and, hearteningly, that most of those changes appear to fade by adulthood.
In older mothers, there is a higher risk of those marks affecting genes themselves (not just the gene expression), with a much higher risk of Down syndrome, for example.
Kindsfather and colleagues wanted to investigate the root of all this: what impacts gene expression, is it due to age, technology, or a blend of the two?
They studied two groups of mice of all ages. The control group conceiving naturally, and the other group underwent various fertility treatments – some receiving hormone treatment, some having their embryos grow in a petri dish, some undergoing both.
The scientists measures the number of epigenetic changes in each embryo at various stages.
They found hormone therapy and time in the petri dish both affected gene transcription – and even more so when the two techniques were combined.
Meanwhile, maternal age, on the other hand, had no impact on gene expression.
‘It wasn’t what we were expecting,’ Dr Mellissa Mann, a professor of reproductive sciences at the university and a senior author on the paper, said.
‘We know that as a woman ages, there are a lot of molecular changes happening to her eggs, so we thought that these changes could be leading to abnormal DNA methylation. We were quite surprised that it didn’t.’
