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The Next Generation of IVF: One by One

Posted on 3.11.17

By Christian Ottolini

In the first of our three-part series on One by One IVF Dr Christian Ottolini, Laboratory Manager for Preimplantation Genetics, explains what it is and how this programme is changing the way that we think of IVF.

One healthy embryo = One healthy pregnancy

One by One IVF is an innovative approach to IVF that moves away from the usual method of collecting the egg and returning the embryo to the uterus within the same cycle. There is good evidence to suggest that simultaneously stimulating to collect eggs and preparing the uterus does not result in the optimal conditions for either. The aim of the programme is to have one healthy baby.

In One by One IVF we carry out the egg collection, create the embryos and then freeze them all. Then, in a subsequent cycle, we can optimise the environment of the uterus for the embryo before we do the transfer (Figure 1). This means that we can match the age of the embryo with the preparedness of the uterus.  If the first embryo doesn’t implant then we can use what we learn from the process to optimise the transfer in a subsequent month – and so on. Once embryos are frozen it affords us this flexibility of transferring them one-by-one, hence the name of the programme.

Figure 1

High Success Rates

OnebyOne IVF is possible due to the huge improvements in freezing technology (i.e. vitrification) and embryo culture (including time-lapse microscopy) that have been seen over the past few years in the field.  We are putting these technologies at the centre of our programme and our preliminary results show that it optimises the chance of taking home a healthy baby with high success rates (Figure 2).

Figure 2


Selecting a healthy embryo with One by One IVF Plus

One of the other advantages of freezing all blastocysts in any given One by One IVF cycle is that it is then possible to screen them to ensure they have the correct number of chromosomes (Figure 3).

Figure 3


A major reason why IVF fails is genetic instability i.e. that the chromosomes are not all present in pairs or that there are bits missing. Once a woman passes the age of 35, the majority of embryos produced from her eggs are chromosomally abnormal, and a chromosomally abnormal embryo will not result in a normal pregnancy. Down’s syndrome is caused by an extra copy of chromosome 21 and other configurations of chromosomes can cause potentially life-threatening disabilities, miscarriages and failed implantation—something sadly prevalent among IVF patients, especially for potential mothers over the age of 35. To have that overwhelming joy of discovering you are pregnant only to lose the baby several weeks later is devastating and we aim to avoid this by only transferring healthy embryos that we now have the right number of chromosomes and no obvious defects.

This genetic screening approach is called pre-implantation genetic screening (PGS) and it can be added on to the One by One IVF programme - we call this package One by One IVF Plus.  It can offer patients reassurance that the embryo transferred will not be chromosomally abnormal. Thus, increasing pregnancy rates per embryo transferred and, in certain cases, informing them whether they are going to need another cycle of IVF, go down the donor conception route, or even explore other treatment options without spending thousands of pounds on unsuccessful standard IVF cycles.

The Bridge Centre has a long legacy of preimplantation genetic testing and is one of the worlds pioneering centres specialising in the field. Collectively the current One by One IVF team at the Bridge Centre has over 60 years’ experience in reproductive genetics. Lead by Professor Alan Handyside, the father of preimplantation genetic diagnosis, the team continues to innovate, leading the way in reproductive genetic testing in the UK and achieving exceptional results.

For more information on our innovative One by One IVF programme, why not attend our next open day on 2nd December.  To book your place please visit



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