In the future will women be able to freeze their eggs, choose the genetic make-up and the sex of their baby? Dr Chris Brown takes a look at current research, which will influence the way infertility is treated in years to come.

Choosing the sex of your baby is already a possibility, though not an option on offer to most couples, unless there are strong medical reasons. It is also possible to freeze human eggs, thaw them at a later date and use them to generate embryos for transfer in an IVF cycle.

Treatments for infertility are continually developing and there’s no doubt that more major scientific developments are on the way. At the moment, research is mainly focused on three developments; blastocyst transfer and pre-implantation genetic diagnosis and pre-implantation genetic screening.

Pre-implantation genetic diagnosis (PGD) is a highly specialised technique enabling the screening of embryos for certain genetic disorders. It can be used, for instance, to determine the sex of an embryo, where a family is at risk of passing on a serious gender-linked disorder, such as Duchenne’s muscular dystrophy, to a male child. Also, if a man and women seeking treatment are both carriers of the cystic fibrosis gene, they would have a 1 in 4 chance of having a child born with the disease, and only a 1in 4 chance of having a baby that wasn't either a carrier or affected by the disease. By undergoing IVF and then removing a single cell from each of the embryos, the geneticist can look for the disorder. Those embryos not affected with the disease can be identified and transferred to the uterus.

PGD is currently used on a relatively small scale, but over 1000 babies have already been born worldwide using PGD. , but over 1000 babies have already been born worldwide using PGD. In the UK, 8 clinics are licensed to offer this treatment. Among the conditions currently screened for by PGD are cystic fibrosis, muscular dystrophy, Sickle cell disease, Huntingdon's disease, and haemophilia. But the range of possible disorders that can be detected is expanding and also covers diseases that don't occur until later in life such as familial breast or colon cancer.

Pre-implantation genetic screening (PGS)is similar to PGD in that a single cell is examined following IVF. This allows the chromosomes of the embryo to be examined and for the doctor to select only the chromosomally normal embryos for transfer. In the UK, this is licensed in 8 clinics, for use in older women who have a higher incidence of babies with chromosomal abnormalities such as Down's syndrome.

The Human Fertilisation and Embryology Authority, the statutory body which regulates, licenses and collects data on all aspects of fertility treatment and research, is monitoring all these developments closely. The authority rejects the prospect of using PGD to create ‘designer babies’ or to test for social, physical or psychological characteristics. The findings of a public consultation carried out jointly by the HFEA and the Advisory Commission on Genetic Testing are due to be published soon.

Blastocyst transfer is not a new technique but is being used to try and reduce the risk of twins and triplets. Instead of placing two or three embryos into the uterus three days after egg collection, the embryologist can culture them within a specialised medium until day five. At this stage some of the embryos will have formed a blastocyst. This is the final stage of development just prior to implantation. It is hoped that by extending this culture period, the embryo with the greatest potential will be selected; a ‘survival of the fittest’ philosophy.

At the moment this technique is reserved for couples who have had several failed attempts in the past, or for those who can only contemplate becoming pregnant with one baby and therefore want a single embryo transfer. Further studies are needed before this technique can be introduced more widely.

In January 2000 the HFEA decided to allow the use of frozen eggs in fertility treatment in the UK. A world wide report commissioned by the authority confirmed the increase in the number of healthy babies recently born from frozen eggs. At the moment this technology is mainly used in this country to help young women who have cancer and need chemotherapy or radiotherapy, which will probably render them sterile. Freezing their eggs allows them to ‘bank’ them for later use, so that they have a chance of giving birth to their own genetic children.

In the future – who knows? – this same technology could be used to allow young women who want to postpone starting a family, to store their eggs for later use. Clearly the ethical implications of these techniques have to be considered and legislated for but future generations might well see this as a solution to the career women’s dilemma about when to start a family.

For more information see other related articles:

The cost of IVF
IVF - what you need to know.
Age and fertility.