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Work done at the University of Aberdeen in Scotland has developed for modern IVF treatment what we think is quite a reliable predictor of the chances of a live birth. A very controversial topic. On the line from Aberdeen is the lead author of this paper, Dr David McLernon, who is a research fellow in medical statistics. Welcome to the Health Report.

David McLernon: Hi Norman, nice to speak to you.

Norman Swan: What are the elements of the prediction here?

David McLernon: Okay, so what we did was we developed two novel online calculators. The first one uses information from the couple that's available before they actually start IVF, such as the age of the woman and the diagnosis of their fertility problem. We use that to predict their overall chance of having a baby over an entire package of IVF treatment.

And then there's a second calculator which then updates these predictions using further information that's available after the first attempt such as the number of eggs that were collected, and the number of embryos that were transferred.

Norman Swan: And of course what's called cryopreservation, because there is increasing evidence which is not there in other predictors which is that frozen embryos seem to do better than fresh embryos.

David McLernon: Yes, so we also included cryopreservation status of embryos. There are quite a few trials going on globally at the minute to compare the effect of fresh and frozen embryo transfers, and I think one or two of them have results already that show that the live birth rates are no worse with frozen embryos.

Norman Swan: So just take us through some of these factors in your calculator. So a woman's age, you compared a woman who is aged 31 versus 37.

David McLernon: Yes, that was only to present the results in a clear manner. We used all women's ages…

Norman Swan: I'm sure, but this is an example so people can hook onto it. So if you are 31 versus 37, your chances were 66% better just for being a bit younger.

David McLernon: Yes, but we all know that the effect of women's age on the chances of having a baby decline from around the age of 30 onwards, and they get worse from about 35 to 50.

Norman Swan: And duration of infertility pre-treatment also had a predictive value.

David McLernon: Yes. So obviously the longer you've been trying to get pregnant the more your chances of having a baby.

Norman Swan: What about post-treatment predictors? So the number of eggs collected?

David McLernon: Yes, so we showed that the more eggs that you've collected in your first IVF attempt increase your chances of having a baby. Up until around 13, 14 eggs and at that point then your chances actually stay quite steady with further eggs that are collected.

Norman Swan: And having a frozen embryo makes a huge difference.

David McLernon: Yes…

Norman Swan: Almost doubles your chances.

David McLernon: Yes, it does, that's just a marker of the quality of the embryos that the women have. So the more embryos you have that are top-quality, the more chance of having enough left over after your fresh embryo transfer to freeze to use later on.

Norman Swan: You illustrate this with a case study. So one is pre-treatment, a 30-year-old woman with two years of unexplained infertility. What are her chances?

David McLernon: Okay, so we showed that her chance of having a baby after the first complete cycle of IVF was 46%. Over three complete cycles it's 79%. When they say complete cycle we are including all embryo transfers, that's about one episode of ovarian stimulation.

Norman Swan: And the stage at which the embryos transferred also makes a difference. So then if she has a fresh embryo cycle it drops considerably.

David McLernon: If she has a fresh embryo…?

Norman Swan: So her chances almost halve…you talk about when she has run out of embryos and there's no freezing, then the chances drop quite dramatically.

David McLernon: Yes, that's because she hasn't got enough frozen embryos left in order to carry on to increase her chances. It's all a cumulative effect that we are measuring here with this model. So if you've only got one fresh embryo, your chances, yes, are quite low.

Norman Swan: So what about the male partner? You've assumed that that's constant, there's no problem with the male partner?

David McLernon: Yes, unfortunately the national data that we use from the Human Fertilisation and Embryology Authority, which is the regulatory body for IVF treatment in the UK, didn't include factors on the males, apart from perhaps the actual diagnosis of infertility, if it was a male factor problem we were able to include that information.

Norman Swan: And you didn't include intracytoplasmic sperm injection, which is almost universal in the Australian context.

David McLernon: We actually did include that as well in the model…

Norman Swan: But it didn't make a difference?

David McLernon: In the post treated model, it showed that…ICSI is intracytoplasmic sperm injection where they inject the sperm into the egg, we showed it just marginally had a slightly lower effect compared to IVF.

Norman Swan: Interesting. So time will tell whether this applies to the Australian context. Lots more questions to ask but unfortunately we have run out of time. Thanks very much for joining us.

David McLernon: Okay, thanks.

Norman Swan: Dr David McLernon who is a research fellow in medical statistics at the University of Aberdeen, my alma mater.

I'm Norman Swan, you've been listening to the Health Report. Please join me next week.

Dr David McLernonResearch Fellow in Medical Statistics, Institute of Applied Health Sciences, University of Aberdeen.

Further Information
Predicting the chances of a live birth after one or more complete cycles of in vitro fertilisation: population based study of linked cycle data from 113873 women - British Medical Journal

PresenterDr Norman Swan ProducerCathy Johnson