No more than a single embryo should be transferred at a time in most younger women undergoing assisted-baby making, according to new guidelines for the nation’s for-profit fertility industry aimed at minimizing multiple births.
But in a recommendation that has some bioethicists alarmed, the guidelines state that doctors can consider transferring up to four or five embryos in women 40 and older.
“Those numbers are still too high,” says Francoise Baylis, Canada Research Chair in bioethics and philosophy at Dalhousie University in Halifax.
“This is actually the worst age group to be pregnant with multiples.”
Fertility doctors say the probability of pregnancy in older women undergoing IVF is so low per embryo transferred that the chances of all embryos implanting is statistically “incredibly small.”
But the recommendation for older women sparked controversy even among the doctors who crafted the guidelines. “These are the recommended maximums — they’re not the routines,” said Dr. Jason Min, chair of the clinical practice guideline committee of the Canadian Fertility and Andrology Society.
“That was the concern, that people would take these as saying, ‘Well, I can do this [transfer five embryos back in women over 42] routinely.’ And that’s not what it says at all,” said Min, of Calgary’s Regional Fertility Program.
Canada has one of the highest rates of multiple births following in vitro fertilization in the world. In 2011, 21 per cent of pregnancies achieved via IVF resulted in a multiple pregnancy, meaning twins or more.
In Canada, the number of embryos transferred during IVF isn’t subject to federal or provincial regulation. Three years ago, Quebec began paying for up to six cycles of IVF with the proviso that only one embryo is transferred per cycle in most women.
Fertility specialists say the goal is to achieve the healthy birth of a single baby. Yet clinics outside Quebec continue to routinely transfer more than one embryo at a time.
In all, 29 of the 31 fertility centres operating in Canada in 2011 reported a total of 1,287 multiple pregnancies, including 1,217 twins, 65 triplets and five quads.
The new guidelines state that single embryo transfers should be routine in women under 35, who are at the highest risk of multiple births. For “poor prognosis” patients, the recommended maximum is two.
For women aged 40 to 42, the guidelines recommend a maximum of three or four embryos; for women older than 42, up to five, depending on how many days after fertilization the embryos are transferred and the woman’s prognosis for success.
Baylis says the guidelines are too permissive towards older women. “I think physicians need to seriously question what they’re doing putting back in five embryos,” she said.
Some studies have found a twin delivery rate as high as 37% with the transfer of five embryos in women over 40.
Fertility specialists say older women usually don’t produce enough top-quality embryos and that more are transferred in the hope that at least one will implant and lead to a baby.
“That’s why we put in more,” said Dr. Al Yuzpe, co-founder and co-director of the Olive Fertility Centre in Vancouver. “It’s a matter of what you have.” He said that the implantation rate in women aged 43 and 44 is 4.7%, compared to 37% for women under 35.
Yuzpe has never transferred five embryos into a woman over 40, though he does routinely transfer four. He said his twin pregnancy rate when four embryos are used is about 12 per cent. “And that’s a pretty low risk,” Yuzpe said.
Live birth rates are so poor in women over the age of 40 “that you’ve got to do what you can do to help these patients,” Yuzpe said.
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