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Mechanism of action of intrauterine devices
Medical expert of the article
Last reviewed: 04.07.2025
There are several theories explaining the mechanism of contraceptive action of intrauterine devices.
The theory of the abortive effect of intrauterine devices. Under the influence of intrauterine devices, traumatization of the endometrium occurs, prostaglandins are released, the tone of the uterine muscles increases, which leads to the expulsion of the embryo in the early stages of implantation.
The theory of accelerated peristalsis. The intrauterine device increases the contractions of the fallopian tubes and uterus, so the fertilized egg enters the uterus prematurely. The trophoblast is still incomplete, the endometrium is not prepared to receive the fertilized egg, as a result of which implantation is impossible.
The theory of aseptic inflammation. The intrauterine device, as a foreign body, causes leukocyte infiltration of the endometrium. The resulting inflammatory changes in the endometrium prevent implantation and further development of blastocysts.
Theory of spermatotoxic action. Leukocyte infiltration is accompanied by an increase in the number of macrophages, which carry out phagocytosis of spermatozoa. Addition of copper and silver to the intrauterine device enhances the spermatotoxic effect.
The theory of enzyme disturbances in the endometrium. This theory is based on the fact that intrauterine devices cause changes in the enzyme content in the endometrium, which has an adverse effect on the implantation process.
It is unlikely that the contraceptive effect of IUDs is due to any single mechanism.
Efficiency of intrauterine devices
The effectiveness of this type of contraception (Pearl index from 2 to 0.3) is practically not related to the qualities and characteristics of the consumer, since it requires only periodic monitoring of the presence of the intrauterine device after its insertion.
Medical supervision of women using intrauterine devices
When using intrauterine devices, it is advisable to examine the woman 3-4 weeks after the introduction of the contraceptive, then preventive examinations, in the absence of complaints from the woman, can be carried out once every 6 months.
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