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Less is More? mild versus full ovarian stimulation in IVF

It is maybe the most significant factor that will determine the chance of having a positive pregnancy test after IVF: it is the number of eggs you produce as a result of having your ovaries stimulated during IVF treatment. As you grow older the number of good quality eggs, capable of producing strong embryos with normal chromosomes becomes gradually less. By stimulating the ovaries with hormonal treatments we can increase the number of eggs produced within a menstrual cycle and make up for poor quality eggs and embryos. 

Over the past few years, lots of attention has been paid on the dose of drugs used during ovarian stimulation in IVF and the effect of this on the number of eggs and quality of embryos. Reducing the dose of hormones used to stimulate the ovaries is widely known as “mild stimulation”. Advocates of the mild stimulation treatment propose that such an approach helps most women follow through treatment with less side effects, reduced cost and, quite important, avoid the risks of ovarian hyperstimulation syndrome, the most serious side effect of hormonal treatment during IVF.

Mild stimulation seems to provide a good chance of pregnancy compared to the most conventional stimulation treatments with higher doses used since the introduction of IVF treatment. Initial claims that mild stimulation provides better quality eggs and embryos, unfortunately, have not been proven, despite the initial excitement on the possible association with reduced doses of hormones and quality of eggs. 

Mild stimulation produces a lower number of eggs and this may not be so important in younger ages, however, it may not be of any benefit in advancing age. On the contrary, as you grow older the number of eggs needed to provide a heathy embryo, capable of resulting in a normal pregnancy, increases steadily. In specific, when blood tests suggest ovarian reserve is running low, the choice of having a mild stimulation may not be in your benefit after all. Producing less eggs may mean less embryos and ultimately reduced chances of getting pregnant.

The choice of having a full stimulation or a mild one to produce a sufficient number of eggs will depend very much on the individual case, the ovarian reserve and the woman’s preference, with regards to drug dosing and potential side-effects. It has always been and will continue to be a fine balance between stimulating only as much, causing as little discomfort as possible, without compromising the chance of pregnancy.

©2021, Nicholas Christoforidis, Fertility Matters
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