What are the risks?


Preimplantation genetic diagnosis

All types of medical treatments and procedures have risks and the pre-implantation genetic diagnosis (PGD) team will discuss these with you before you sign the consent form to begin treatment. Please ask questions if you are uncertain.

Potential risks can be split into:

  • risks of PGD treatment
  • risks to children born following PGD.

What are the risks of PGD treatment?

The risks associated with preimplantation genetic diagnosis (PGD) include:

  • Multiple pregnancy

    This is the major complication of PGD however one of our recent successes is that our multiple pregnancy rate is now 1.2%. For most women going through PGD, we recommend that only one embryo is transferred, as the risk of complications is higher in a twin pregnancy. However rarely we may recommend two embryos for transfer, which can result in a multiple pregnancy. 

    Our recent published research shows that transferring a single embryo does not decrease the pregnancy rate, but improves the chance of having a healthy pregnancy. Any additional, unaffected embryos that you create can be kept frozen for possible future use.

  • Ovarian hyperstimulation syndrome (OHSS)

    Some women respond very sensitively to the fertility drugs and develop OHSS. This occurs when many follicles are produced, which causes the ovaries to enlarge to up to three times their normal size. Your blood protein level drops, which causes fluid to leak out into the abdominal cavity or around the lungs. This can result in:

    • problems producing urine
    • mineral imbalances in your blood
    • clotting problems.

    However another of our major successes over the last 18 months is that by changing the way the drugs are taken to stimulate the ovaries we have had no cases of OHSS. This is encouraging, but OHSS is not always predictable or avoidable. It is more common in younger women and those with polycystic ovarian syndrome. If we are concerned that you are at risk of developing moderate or severe OHSS we will keep you under regular review.

    Having OHSS does not reduce the chances of you becoming pregnant.

  • Pelvic infection

    Pelvic infection can occasionally follow an egg collection and, rarely, an abscess develops. We try to make sure this does not happen by performing the collection under sterile conditions and giving antibiotics to women who are at higher risk of infection. It is not always possible to prevent an infection despite these measures.

    If you develop a pelvic infection, we will admit you to St Thomas' Hospital for antibiotic treatment. In severe cases, an operation may be necessary.

  • Other complications

    There is a very small risk that the needle used for egg collection can puncture the bowel or blood vessels. The needle used is very fine and it is unusual to have any complications. Most cases of vaginal bleeding can be stopped at the end of the procedure by applying pressure to the puncture site. If there is a concern that a tiny hole has been made in the bowel, you will be given antibiotics.

Risks to children

  • Risks associated with IVF and ICSI

    The first in vitro fertilisation (IVF) baby was born in 1978 and the first following PGD in 1990. There is evidence that babies born following IVF or intracytoplasmic sperm injection (ICSI) are more likely to be:

    • born early (prematurely)
    • weigh less than naturally conceived babies born at the same age.

    In 2002, a large study from Australia suggested that IVF treatment might almost double the risk of abnormalities. It is important to remember that the risk of an abnormality in a natural conception is about 3%.

    The Brussels Centre, which developed ICSI, has compared the complication rates in children born after ICSI with rates in children born after IVF and found no difference. 
    More research is needed and is ongoing. Please feel free to talk to us about any concerns you might have about ICSI treatment.

  • Risks to PGD babies

    Currently most of the data collected about babies born following PGD only relates to the outcome at birth. We had until 2016 followed up all our PGD babies at birth and between one and two years of age. We no longer offer routine follow up as no evidence has emerged of an increase in abnormality rate.

    We are however in the process of reviewing our data for publication.




Contact us

Genetics enquiries and potential patients

Tel: 020 7188 1392
Email: pgdgenetics

Email: gst-tr.

Assisted Conception Unit (ACU) enquiries and current patients

Tel: 020 7188 2300
Email: IVF.PGD@

Patient stories

Hear from couples who have been successfully helped by our centre.