The copper (Cu)-bearing intra-uterine device (IUD)

The copper IUD can be inserted within 120 hours of unprotected intercourse. Various studies have reported that one variant, the Multiload Cu-375 IUD, prevented pregnancy is nulliparous women by 92.4%, and in parous women by 98.1%.(1) (2) Another version, the TCu380A IUD, reduced the pregnancies to 0%. It was 100% effective. (3) Based upon data gathered from long term users of copper (Cu) IUDs, a variety of mechanisms of action are possible when this type of IUD is used as a post-coital anti-pregnancy device.

First, the endometrial expression of HOXA-10, deemed essential for implantation, was absent in IUD wearers. (4)

Second, "copper IUDs can inhibit expression of LIF and they may cause inhibition of the implantation stage, which is crucial for pregnancy." (5)

Third, the copper particles released from the IUD are toxic to spermatozoa, decreasing the chances of fertilization. (6)

Fourth, "IUDs cause a marked local foreign body reaction, which turns the intrauterine milieu lethal for embryos". (7)

And finally, there is the possibility that bacteria have been introduced into the otherwise sterile environment of the uterine cavity. (8)

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(1) Bilian X. Chinese experience with intrauterine devices. Contraception. 2007;75:S31-S34

(2) Liying Z, Bilian X. Emergency contraception with Multiload Cu

(3) Bilian, op. cit., p.833

(4) Tetrault AM, Richman SM, Fei X et al. Decreased endometrial HOXA10 expression associated with use of the copper intrauterine device. Fert Steril. 2009;92(6): 1820-4

(5) Guney M, Oral B, Karahan N et al. Expression of leukaemia inhibitory factor (LIF) during the window of implantation in copper T380A intrauterine device users. 2007;12(3):212-9

(6) Ortiz ME, Croxatto HB. Copper-T intrauterine device and levonorgestrel intrauterine system: biological basis of their mechanism of action. Contraception. 2007;75 (6 Suppl):S16-30

(7) Ibid.

(8) Spinnato JA, Mechanism of action of intrauterine contraceptive devices and its relation to informed consent. Am J Obstet Gynecol 1997; 176(3) 503-506