Yesterday’s conference The Best Possible Start in Life: The Robust and Responsive Embryo, proved as interesting as I thought it might be. I am no scientist so found some of the terminology and the concepts hard to get my head round. Some speakers were better than others at using layman’s language, but the headlines make me want to understand more.
For instance Professor Marilyn Monk of the Institute of Child Health introduced the idea of the Genome as the blueprint or hardware of genetic inheritance and the Epigenome as the software, or the mechanism for the modification of genes, this being a dynamic process that starts in the womb and continues throughout life. Epigenetics is an emerging science but MM thought it likely that it will be found that the lifestyle of parents programmes genetic modifications that are passed to the embryo/foetus/child via their gametes.
Daniel Brison, Consultant Embryologist from Manchester, talked about the impact of the culture medium in which invitro-fertilisation takes place. Not a nice warm journey through the fallopian tubes to a cosy, thick uterine lining, but a static plastic dish full of chemicals…albeit friendly, specially selected ones. Development of animal embryos outside the womb has taken place for many years now. The cultures in which they grow have been optimised for successful development through experimentation with the many animal embryos that are available. The cultures in which human embryos grow have not been able to be optimised in the same way because of the ethical and practical difficulties of using human embryos for experimental purposes. The impact of the culture medium on embryos is unknown as yet but Dr. Brison said that it was worth noting that blastocysts, which are transferred or frozen at five days, are exposed for longer than traditional three day embryos and that very important development takes place between days three and five.
Dr. Maureen Wood from Aberdeen University’s Department of Obstetrics and Gynaecology talked about advances in cryopreservation of embryos and eggs. Some clinics are moving from traditional freezing techniques to the newer vitrification method but comparison between the techniques for embryos has not been useful because there are so many differences between the protocols used by different clinics. The long-term impact on embryos or eggs, if any, of any type of cryopreservation is at yet unknown. Vitrification of eggs has now been refined to the state where it is a viable proposition for a woman to ‘freeze’ her eggs when young, or prior to chemotherapy, to be used later. A clinic in Valencia apparently has good data showing almost identical pregnancy and live birth results when using either fresh or vitrified eggs in IVF cycles. On the question of whether ‘social’ egg vitrification should be encouraged, Dr Wood and other presenters felt that this was for society to debate. At least one panel member felt strongly that we should return to times when women had children at a younger age rather than being able to postpone motherhood to much later years.
All the speakers emphasised how very difficult it is to know which embryos, when transferred to the womb, are likely to result in a successful pregnancy. I was shocked by Simon Fishel’s statistic that between 50 to 80 per cent of embryos are non-viable. I recall my son Peter and his wife Emily talking about the perfect single blastocysts they had transferred for two of their IVF attempts. The first resulted in a missed miscarriage at 8 weeks of identical twins (and splitting of blastocysts resulting in twins was highlighted as another issue of concern) and the second, transferred five months later, in our lovely grand-daughter. Professor Helen Picton, in a particularly accessible presentation, demonstrated the huge difficulties in choosing which embryos to transfer. We saw pictures of embryos with perfect symmetry that did not result in pregnancy and those looking lopsided and distorted that did. Professor Picton’s particular contribution was about the metabolism of the embryo. Apparently those with the lowest level of metabolism, the ‘quiet embryos’ are more likely to be developmentally competent. So, counter-intuitively, the three day cleavage embryo or the blastocyst that takes a little longer to develop may be more likely to result in a pregnancy, than the one that appears to be the front-runner for transfer. It is very clear that, just like human beings, some embryos are just more responsive and more robust than others. It is just very difficult to tell which is which.
The One at a Time http://www.oneatatime.org.uk/ message was very strong from all participants but particularly Jane Denton from the Multiple Births Foundation. Jane emphasised the importance of only transferring one blastocyst, even in older women, because of the incidence of blastocysts splitting and the possibility of a very high risk triplet pregnancy when two blastocysts are transferred.
Andre van Steireghem from Belgium was able to give good news of the health of children who have come into being with the help of IVF and ISCI. His unit in Brussels is following up 16,000 children conceived in these ways. He has found that children conceived using assisted reproduction (ART) were one a half times more likely to be small for dates or have low birth weight and twice as likely to die before birth. Twins – and half of all ART children are not singletons – have a ten times higher rate of cerebral palsy, but this is true of unassisted twin conceptions as well. There is a slightly higher malformation rate in children conceived through ART but Professor van Steirteghem said this was likely to be linked to the underlying infertility of the couple…although he didn’t say how. For singletons, the health risk factors of ART appear very small so far, but it will be many years yet before the long-term risks and effects can be judged and there are very few good follow up studies.
It was a fascinating day that had me puzzled and bedazzled in equal measure. The presentations were from leaders in the field and I have not done justice to them here. Thank goodness Bio-News http://www.bionews.org.uk/home will be producing reports from all the speakers over the next few weeks so do watch out for those. I’ll just end with a sentiment that was shared by all speakers in one way or another. Daniel Brison concluded his ten minute slot with a plea for more and better follow-up studies because as he said, ‘Our primary duty of care is to the children, and not the parents’. I’ll drink to that.