Why do doctors continue using intramuscular progesterone ?

All IVF clinics routinely provide luteal phase support after the embryo transfer. This consists of a combination of both estrogen and progesterone , which are used to prepare the endometrium for embryo implantation .

In the past , progesterone was given in the form of intramuscular injections. Progesterone is an oily preparation , and needs to be given deep intramuscularly, with a fat needle. Not only is the injection painful, because the absorption is poor, the shots will often leave tender lumps in the muscles  , and these take many days to resolve. Often the butt is so sore that the poor patient cannot even sit down anymore.

Many patients who have been given intramuscular progesterone will refuse to do a second IVF cycle, simply because the progesterone shots have left them so miserable . Often, the thought of taking the injections again is far more painful than the idea of having to cope with a failed IVF cycle. This is true for the poor husband has well, who hates having to give his wife these excruciatingly painful injections. Many of them feel it’s not worth having a baby if they have to put their wife through that kind of pain.


Fortunately , thanks to technology , we now have far better preparations for progesterone . This includes micronized progesterone , which can be administered vaginally, in the form of either a gel or a suppository . These formulations have been  available for over 20 years, and we stopped  using intramuscular progesterone in our clinic 20 years ago.

What amazes me is why some clinics continue to inflict so much unnecessary pain on their patients by insisting that they continue taking intramuscular progesterone. If IM ( intramuscular) progesterone were proven to improve IVF pregnancy rates because it’s more effective than vaginal progesterone, I would have understood. However, the truth is that it is no better – and this has been proven in many clinical trials. This is because the absorption from the intramuscular route is much worse . Also, when the progesterone gets absorbed into the bloodstream , it is metabolized in the liver, which breaks it down, as a result of which the levels of progesterone which reach the target organ – the uterus - are reduced.

In contrast, when we deliver the progesterone vaginally, it is directly absorbed and much higher levels reach the uterus – which is where we want it to act ! Some clinics measure blood levels of progesterone, but this is quite pointless, as we are interested in the tissue levels of progesterone in the endometrium – not the blood levels.

Ironically, some patients seem to prefer the IM route . They seem to have a medieval hangover which leans them to conclude that if it is painful, it must be more effective ! 

I cannot understand why doctors continue to inflict unnecessary pain on their patients by prescribing IM progesterone ! Is it just because this is what they have been used to doing, and therefore plan to continue doing it, no matter what the clinical evidence is ? Or is it that because most IVF doctors are men , they are blissfully unaware of how unkind they are being, and fail to understand how much damage they are inadvertently inflicting on their poor patients ? Patients expect injections to be painful, and will rarely complain about this to their doctors, because they feel they cannot afford to trouble their doctor with such trifles.

If I were an IVF patient , I would never take intramuscular progesterone - I would insist that it be given vaginally. I see no reason why we should subject our poor patients to unnecessary pain !


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