Could an earlier frozen embryo transfer mean better success rates?

New research carried out by UK’s Oxford Fertility clinic has shown that transferring a day earlier, six days after ovulation rather than seven, could result in a higher success rate

The study looked at hundreds of assisted fertility procedures and revealed that 45% of women that had a frozen embryo transferred six days after ovulation “went on to have a pregnancy beyond 24 weeks”.

Of the women who had the procedure a day later, seven days after ovulation, 29% went on to have a pregnancy beyond 24 weeks.

The success rates remained higher at six days post ovulation in all age groups and the miscarriage rate was the same for both groups of women (day six and day seven transfers).

This data, based on 561 frozen embryo transfers was presented at the Fertility 2020 conference in Edinburgh last week

This research could help to change the day on which the procedure is carried out for all women.

Medical Director at Oxford Fertility, Professor Tim Child says that the evidence collected suggests that the day of transfer is important to the success of the procedure.

British Fertility Society chairwoman, Dr Jane Stewart says that so far, “the findings are not strong enough to implicate how clinics pick the day of embryo transfer. It varies between each clinic and IVF patient.”

She went on “This research seeks to answer an important question about the timing of embryo transfer when using frozen embryos. At present, it doesn’t justify a change in clinical practice. It does add an important element to the body of knowledge on this issue.”

“The study only looked at women who had their thawed embryos transferred during their natural cycle, as opposed to a hormono-regulated cycle. In a hormono-regulated cycle, the woman’s ovaries and her hormones are effectively ‘switched off’.”

“She is then medicated with synthetic hormones to prepare the lining of the womb so the embryo can attach. The natural cycle option avoids medication, which can have side effects, and relies on predicting the women’s natural hormones. Medics monitor the woman’s hormones so they can implant the embryo at the right time when the womb lining is thick enough.”

The NHS says that both methods can be effective, but using the natural method means that the timing of ovulation is outside of anyone’s control.

The ideal thickness of the womb lining might land on a day that the clinic isn’t open for the procedure.

Professor Child says that his findings demonstrate that IVF can be very successful using the natural method

He says “This research not only reveals the best time for implantation in a natural cycle, when the body is most ready to receive an embryo. But it also demonstrates how we can achieve very good pregnancy rates with a natural, drug-free treatment. Most clinics are not doing a natural cycle, they are doing medicated or a natural cycle plus drugs. You don’t need to be subjecting women to medications, hormones and pessaries.”

IVF babble will certainly be keeping a close eye on developments and will, as ever, keep you fully updated.

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