Mild/Natural IVF

Mild stimulation or modified natural cycle IVF uses lower doses of fertility medication than conventional “full stimulation” IVF.

The drug dosage is enough to encourage at least one follicle to develop and to promote egg growth. As in traditional IVF, once your eggs are ready an injection of hCG or GnRH agonist is given to trigger egg maturation, followed by egg collection.

To help support your body and implantation of the embryos after transfer, progesterone supplements are also given.At Harley Street Fertility Clinic we only recommend mild stimulation or modifiednatural cycle IVF for very few patients because of its high cancellation and very low success rates.


It’s important to remember that even with a modified approach, there is a much higher risk compared to conventional IVF that your treatment cycle will be stopped for poor response, no eggs will be collected, of failed fertilisation or embryo development. Furthermore, you will not have as many eggs to fertilise, and resulting embryos to transfer, through mild stimulation or modified natural cycle IVF compared to conventional treatment. You are also very unlikely to get any embryos for freezing.So mild stimulation or modified natural cycle IVF isn’t something that’s suitable for every patient. We will discuss with you whether it is something you could consider, based on your individual test results and previous treatment history. We would only recommend it as an option if we think it gives you a good chance of success.

Who might this benefit?

Modified Natural Cycle IVF may be of benefit if:

  • You are over 43 years old
  • You’ve responded very poorly to IVF stimulation
  • Your results show you have a very low AMH level
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