Pre-implantation genetic testing (PGT-M/SR)
Our pre-implantation genetic testing (PGT-M/SR) service has been offered at Guy's Hospital since 1997.
PGT, formally known preimplantation genetic diagnosis (PGD), helps couples who are at risk of having a child with a serious genetic condition. This could be a genetic condition caused by one gene ('monogenic' or PGT-M), or a chromosomal structural rearrangement ('structural rearrangement' or PGT-SR). Together, they are known as PGT-M/SR.
This is a special type of in vitro fertilisation (IVF). Embryos are created outside of the body and are tested for the genetic condition in the family. Only embryos which are not affected by the genetic condition are placed back into the womb.
We test for more than 300 genetic disorders, including:
- cystic fibrosis
- sickle cell disease
- Huntington's disease
We're the largest centre in the UK and one of the most successful in Europe.
We work with the genetics service and the assisted conception unit.
We also have 3 satellite centres in Exeter, Leeds and Sheffield. The satellite centres can arrange genetic counselling and fertility treatment locally. You'll still need to come to Guy's Hospital for the egg and sperm collection, and embryo transfer.
Please contact the satellite centres for more information.
Success rates are published by the Human Fertilisation and Embryology Authority (HFEA). About 1 in 3 cycles of PGT-M/SR will result in a baby. If a couple completes the process and has embryo(s) suitable for transfer, there is about a 1 in 2 (50%) chance of a pregnancy.
Details about our success at each step of the PGT-M/SR process.
Number of cycles
- 2015 - 396
- 2016 - 423
- 2017 - 435
- 2018 - 436
- 2019 - 483
- Overall (1997 to 2019) - 3,828
Number of embryo transfers
- 2015 - 241
- 2016 - 283
- 2017 - 262
- 2018 - 243
- 2019 - 281
- Overall (1997 to 2019) - 2,538
Clinical pregnancy rate is defined as a pregnancy which has been confirmed to have a fetal heartbeat on an ultrasound scan, not just a positive pregnancy test.
- 2015 - 124
- 2016 - 111
- 2017 - 129
- 2018 - 124
- 2019 - 147
- Overall (1997 to 2019) - 1,112
Clinical pregnancy rate per cycle of PGT-M/SR (%)
- 2015 - 33.5%
- 2016 - 29%
- 2017 - 29.5%
- 2018 - 28.5%
- 2019 - 30.4%
- Overall (1997 to 2019) - 29%
Clinical pregnancy rate per embryo transfer (%)
- 2015 - 40%
- 2016 - 46%
- 2017 - 49%
- 2018 - 51%
- 2019 - 52.3%
- Overall (1997 to 2019) - 44%
We take immense pride when each child is born following a successful PGT cycle. Over 1,000 babies have been born following PGT at Guy's Hospital.
Your feedback is very important to us as it helps us maintain high levels of service and satisfaction. Please talk to us if you are unhappy with any aspect of your PGT treatment. We'll do everything possible to put things right.
It took 15 months from initial referral to first embryo implantation. This was the biggest challenge for Christina.
Christina found the injections to increase egg production daunting but her husband, Joel, managed these for her. The egg collection process went well and the couple had 26 eggs collected.
Only 6 embryos survived the initial growth period and of those, 3 could be transferred.
The first embryo transfer was unsuccessful. The team supported Christina and Joel during this difficult time and answered all their questions.
Their second embryo transfer was successful. The couple welcomed daughter Ella into the world on 7 May 2020.
Christina said: "I can't thank the team at Guy's and St Thomas' enough for their guidance throughout this process and ultimately giving us the greatest gift of them all, a beautiful baby.
"For other couples considering PGD, I would say patience and communicating with your partner are key and when things are difficult, keep picturing the end goal."
Chris carries the gene for Huntington's disease. A natural birth meant a 50/50 chance of their baby getting this disease.
The process took about 1 year. The PGD team collected 17 eggs of which 2 were suitable for testing.
Unfortunately the first embryo transfer was unsuccessful. The next embryo transfer in August 2019 was successful.
Their daughter Emily was born on 4 May 2020.
Natalie says: "From start to finish the doctors and nurses at Guy's Hospital were nothing but helpful, informative and supportive every step of the way. If you are worried or have concerns about PGD, I would highly recommend just talking to someone there and have your questions written down.
"I can’t wait to tell Emily all about her entrance into the world".
Elena was born with neurofibromatosis type 1, and is only mildly affected by the condition.
The first stage of PGD involved multiple appointments, forms and tests and starting injections to increase egg production. Initially the injections were scary, but she soon got into a rhythm with Nick doing them for her.
She had 29 eggs extracted and 14 of them were fertilised. 4 embryos were suitable for implantation.
Elena started medication for the embryo transfer and had regular scans. Her most memorable side effect was unbelievably itchy skin.
Elena felt uncomfortable during the transfer, but no worse than a smear test and it was quick.
Their daughter Evie was born on 5 February 2019.
Elena says: "I am incredibly grateful for the brilliant team at Guy's, both in the assisted conception unit and the neurofibromatosis clinic. Before we started the PGD process we were nervous, aware of the success rates and how tough it can be. We were lucky it worked on the first attempt. The process was hard from managing expectations, appointments, medication and its side effects to riding a roller coaster of hormones and uncertainty. However, it was also an incredible journey. The process brought us closer together, we were relaxed and supporting each other."
"My top tips are not to obsess over statistics, avoid online chat groups and Google dives, write your questions down, keep busy, don't let the process consume you but take the time to look after each other, relax and keep everything crossed, it might just work."
Michelle and Russell consider themselves extremely lucky that PGD was successful first time for them. Without treatment there was a 50/50 chance that their child would have neurofibromatosis 1.
At first they questioned if this was the right way to start a family, but after much discussion they both agreed it was.
They found the treatment easier than first thought and they found the most difficult part was waiting for the phone call to tell them if and how many healthy embryos there may be to use. They only had the one, but she was a fighter and they now have a beautiful daughter Lila. Michelle and Russell will remain ever grateful for what everyone has done for them.
Verginiya and Angel desperately wanted to start a family but a family history of polycystic kidney disease on the husband’s side never gave them piece of mind. The chances of their child having the disease was 50\50 and they did not want to take the risk.
Verginiya and Angel began researching on how they could have a healthy baby and spoke to their GP. They were referred to a genetic consultant who explained all the options available. One of them was PGD. After the consultant explained it in detail they immediately knew they wanted to proceed. As the couple were unable to afford PGD they were interviewed in order to be approved for NHS funding.
Verginita said "the day of the interview came and we met our lovely and so amazing genetic counsellor. At the end of the interview she told us we were approved and we couldn’t believe it. It was happening. One year later my cycle started and our beautiful and healthy baby daughter, Anna came to the world on December 25 2015. Our dream came true and we couldn’t be happier. We can’t thank all of the PGD team in Guy's and St Thomas' Hospital enough for all of their efforts and hard work to make this miracle happen."
One couple who have been helped by the centre are Michael and Emma from Wiltshire. Michael and their son Joshua are both affected with neurofibromatosis type 1(NF1), a condition that can cause multiple tumours in different parts of the body possibly leading to complications in the eye or spinal cord, and in rare circumstances can become malignant. Some children will also have learning difficulties.
Emma said "neurofibromatosis is a bit like a lottery as you have a 50 per cent chance of passing it on and due to its varying nature, it is impossible to predict how severe the effects will be.
"When we were told that NF was on the list of conditions accepted for PGD, we were ecstatic, and applied for PGD funding.
"We started the course with some trepidation, not knowing what to expect, or how far through the process we would get. When the pregnancy test came back positive we were both over the moon."
9 months later, Emma gave birth to baby Oliver who weighed 7lb 7oz. She added "he is not only healthy but he is free from NF1 which is such a relief. The staff at Guy's and St Thomas' have been fantastic and we were looked after throughout the entire process. We only hope that many others are able to benefit from the same fantastic treatment in the future."
Some couples undergo PGD to help ensure they have a child unaffected by an X linked condition such as Duchenne muscular dystrophy.
Duchenne muscular dystrophy is a severe life limiting condition and mainly affects boys who have symptoms from about two years of age. Many of the families we treat will have grown up with and cared for affected, brothers, uncles, cousins or nephews.
Manuela Hayes recommends PGD to couples that have the worry of passing a genetic disease to their children.
Manuela said "PGD was able to take away the scariest decision parents have to make, which is whether to have a termination. Parents may have to face this decision when they know their child will be afflicted with a disease that will affect both the child’s quality and length of their life. Whichever decision you make in that situation you are left with lifelong emotional scars.
"While going through PGD it felt like our PGD genetic counsellor was genuinely invested in the process with us and regularly provided updates and information.
"We felt supported through the whole process, and the steps were explained in a way which enabled us to have a good understanding of them. This meant that we could make an informed choice of how to proceed.
"We cannot thank the PGD team enough for helping us and for the wonderful daughter we got from the PGD process."
NHS website: In vitro fertilisation (IVF)
Human fertilisation and embryology authority (HFEA) is the regulatory body for fertility treatment in the UK
Our team is made up of:
- genetic counsellors and geneticists
- fertility counsellors
- fertility doctors
- administration team
Charlotte Tomlinson, consultant genetic counsellor and clinical genetics PGT-M/SR lead
Muriel Holder, consultant clinical geneticist
Francesca Forzano, consultant clinical geneticist
Yacoub Khalaf, director of the pre-implantation genetic testing (PGT-M/SR) programme
Tarek El-Toukhy, lead of the assisted conception unit (ACU)
Jan Grace, consultant in reproductive medicine
Davinia White, consultant in reproductive medicine
Our genetic counsellors
Senior genetic counsellor, team leader for PGT-M/SR and general genetics
Principal genetic counsellor
Our clinical fellows
Senior clinical fellow in fertility
Senior clinical fellow in fertility
Research and clinical trials
We're constantly researching and auditing our service to make sure our success rates continue to improve.
We're licenced by the Human Fertilisation and Embryology Authority to undertake scientific projects which are important for the continuing development of treatment.
We may ask if you would be interested in taking part in our research. This could be by:
- answering questions about your experience
- donating sperm, eggs and embryos
You don't have to take part in any research. Your eggs, sperm, and embryos donated to research are never used to treat other people.
Last updated: 20 January 2023