IVF Treatment - Hormone stimulation

Although we occasionally perform ART. on 'natural' cycles (where only one egg might be collected) it has been proven that results are much better if medication is used to promote growth of more follicles so that more eggs can be collected. Normally about 20 follicles start to develop in each menstrual cycle but only one goes on to release an egg (called ovulation) and the others die and dissolve away.

The hormonal stimulation we use aims to increase the proportion of eggs that are ready to ovulate from 1 in 20 to perhaps 8 to 10 in 20 – (NB. therefore we don't 'use up' more eggs so women undergoing treatment do NOT go through the menopause earlier). This allows us to collect more ‘rescued’ eggs and therefore we have a higher chance of achieving fertilisation and subsequent pregnancy but we need to be cautious to avoid over-stimulation. The chart below adds some further explanation to the use of the hormone stimulation.

You will see that the average number of eggs collected is nine (9) but from those we only, on average, end up with three apparently healthy embryos. Put another way, around two thirds of the eggs do not end up as embryos, so to allow for this we want a good number to start with. If we have three embryos, couples might elect to transfer two, leaving one embryo to be frozen and transferred at a later time if a pregnancy does not occur. This gives them another chance from one lot of stimulation and procedures – once again please be aware that this is an average and everybody responds differently.

To stimulate this multiple follicle development, we usually use a combination of a GnRH analogue either Synarel (Nafarelin) or Lucrin (Leuprolide), and FSH (Gonal-F or Puregon). Occasionally we may also use Ganirelix or Cetrotide. The drugs used are discussed in more detail on the "Drugs used and their side effects" page. All treatment is individualised.