IVF Treatment: Higher Likelihood Of Babies Born Alive When Eggs Are Collected In Summer

In IVF treatment involving frozen embryo transfer, the time of year when eggs are collected from women’s ovaries makes a difference to live birth rates, says a study.

Struggling to conceive and considering going for IVF treatment? Summer may be the best time to start fertility treatment. A new study published in Human Reproduction journal has indicated that the chances of IVF babies born alive may be associated with the time of year when eggs are collected from the ovaries for fertility treatment.

For in vitro fertilization frozen embryo transfers, the researchers found a 30 per cent higher likelihood of babies being born alive if eggs were collected in the summer, compared to the eggs retrieved in the autumn.

The improvement in birth rates associated with egg collection in summer was seen regardless of when the embryos were transferred to the women’s wombs, according to Dr Sebastian Leathersich, who led the research team in Australia.

Interestingly, the researchers also found higher live birth rates when the eggs were collected during sunny days.

The success rate of frozen embryo transfer

The study estimated the average live birth rate following frozen embryo transfer in Australia at 27 births per 100 people, and the overall live birth rate to be 28 births per 100 people.

The live birth rate was found to be 31 births per 100 people if eggs were collected in summer, and 26 births per 100 people if the eggs were collected in autumn. However, the time of the year when the embryos were finally transferred to the women’s wombs doesn’t make a difference to live birth rates, as stated by the researchers.

For eggs that were collected in spring or winter, the live birth rates stand between these two figures, and the researchers did not find significant differences in these cases.

Additionally, they found a 28 per cent higher chance of a live birth when the eggs were collected during days that had the most sunshine compared to days with the least sunshine.

The effects of seasons on IVF success rates

Today, many couples are freezing their embryos for future pregnancy. But the effects of the seasons on IVF success rates have not been explored much.

To explore the impact of environment on egg development and early pregnancy, Dr Leathersich’s team analyzed IVF outcomes from all frozen embryo transfers carried out at one clinic in Perth over a period of eight years, from January 2013 to December 2021.

Here are key findings of the study:

The live birth rate was more than 25 per cent when the embryo came from an egg that was collected on a day with fewer hours of sunshine.
The live birth rate was more than 30 per cent when the egg was collected on days with the most hours of sunshine.
However, the study found decreased chances of a live birth rate when the embryos were transferred on the hottest days compared to the coolest days, a difference of 18 per cent. The miscarriage rates also increased from 5.5 per cent to 7.6 per cent.

The researchers speculated that melatonin may be one factor that may play a role in the increased live birth rates associated with egg collection in the summer. Usually, levels of this hormone are higher in winter and spring, and it takes three to six months for eggs to develop before they are released from the ovaries. Another factors may be lifestyle differences between winter and summer months, they stated.