Fresh embryo transfers linked to higher birth rates in women struggling to conceive with IVF
Women with a low chance of having a baby through in vitro fertilisation (IVF) may be better off using fresh embryos as opposed to frozen ones, a new study in China suggests.
One in six people worldwide struggle with infertility, and IVF is the most common treatment to help people conceive.
It involves removing a woman’s eggs, fertilising them with sperm in a lab, and then putting the result – fertilised eggs or embryos – back into her uterus.
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Doctors often opt for a "freeze-all strategy" where they retrieve multiple eggs at once and then freeze the embryos to be transferred weeks, months, or even years later.
But the new study suggests this might not be the best approach for women with lower odds of success with IVF, which is based on a handful of factors such as age, underlying health conditions, low egg count, and egg quality.
Higher birth rate for fresh embryo transfers
The study, which was published in the BMJ, included 838 women in their 30s who had only a few healthy eggs.
"How to optimally use the ‘precious’ embryos to increase the chance of live birth in these patients is an important clinical question," Dr Daimin Wei, the study’s lead author and a professor at Shandong University’s reproductive medical centre in China, told Euronews Health.
In the study, women who received transfers with fresh embryos – implanted the same day their eggs were removed – were more likely to give birth than those who used frozen embryos, the study found.
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Among women who had a fresh embryo transfer, 40.1 per cent gave birth compared with 31.5 per cent among those who had a frozen embryo transfer.
Women who had a fresh embryo were also more likely to get pregnant and less likely to have a miscarriage.
There was no difference in babies’ birth weight, neonatal health problems, or obstetric complications between the two groups.
Study limitations
The findings are among the first to assess whether fresh or frozen embryo transfers make a difference for women with a poor prognosis, the researchers said.
Prior studies focus on women with a normal or high likelihood of success with IVF, and show that frozen embryo transfers are at least as good as fresh embryos.
Notably, men’s health and sperm quality can also affect the odds of success with fertility treatments.
The researchers said men contributed to infertility problems in about 17 per cent of cases where women got fresh embryos, and a similar level for those who got frozen embryos.
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The study has some limitations. For example, there were differences in the number of embryos transferred and the stage at which they were transferred, which researchers said could contribute to the disparities between the groups.
Even so, Wei said the findings indicate that fertility doctors should rely more on patient-level information when deciding how to set up their IVF treatments.
"For clinicians, it is suggested to individually choose the embryo transfer strategy based on ovarian response and patients' characteristics to optimise the IVF outcomes," Wei said.
