Natural cycle IVF, or "natural IVF" consists of IVF, with or without ICSI, during which one egg is collected from your ovary in a natural menstrual cycle. No drugs are used to make the ovaries produce multiple eggs, although drugs are given to time egg retrieval.
The advantage of this approach, apart from the fact that you don't need to take any drugs to stimulate your ovaries, is that you don't need to have "resting" cycles between treatment cycles. However, the "price" that is paid for this, is that success rates are very low (about 7% per cycle). The procedure relies upon the natural growth of one follicle, which means spontaneous ovulation can often occur before egg collection. In addition, the single egg can't always be retrieved, or might not be of sufficient
quality to be used when it is, or it can fail to fertilise when it is
placed into incubation. And you have to remember that it is still an invasive procedure as the doctor has to go in and collect the egg.
As you would expect therefore, it is not something that we would normally recommend for most couples, as it kind of falls between the two stools of either IUI of IVF. However, there are circumstances where ovarian stimulation (or the use of drugs for ovarian stimulation) isn't possible, or where ovarian stimulation confers no benefit, in which case it can be a useful way forward.
And, of course, some women are really uncomfortable with the idea of taking any drugs at all unless it is definitely unavoidable, so it can be useful for some couples as a next step if a completely natural approach to conception no longer seems likely to work.
As the next step on from natural IVF, there is now a move towards women having milder drug stimulation. The possible side-effects of the stimulation drugs are reduced - as, of course, is the cost - and there are only very minimal risks of multiple pregnancies. The aim is to collect somewhere between two and seven eggs, whereas in "conventional" IVF we would try to get as many eggs as is safely possible, usually eight or more
As part of of our step-by-step approach, mild IVF is something that we will sometimes suggest that our clients consider, particularly if the female partner is still relatively young.
Success rates are difficult to predict as they depend largely on the relative strength of the drug protocols employed but, as common sense would suggest, they are somewhere between those for "natural" and "conventional" treatments.