Contraceptive

contraceptive [¦kän·trə¦sep·tiv]

(medicine)

Any mechanical device or chemical agent used to prevent conception.

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Contraceptive 

one of various mechanical, biological, chemical, and surgical agents and methods used to prevent pregnancy and one of the most common forms of contraception.

Mechanical contraceptives principally prevent spermatozoa from penetrating into the uterus; they include female contraceptive devices that are inserted into the cervix and uterine cavity and male condoms. Chemical contraceptives act on spermatozoa that have entered the vagina by immobilizing them and depriving them of their fertilizing capacity. Some scientists regard synthetic preparations that have a general resorptive effect on the body to be chemical contraceptives. It is more accurate, however, to regard them as biological contraceptives. Agents of chemical contraception used locally include globules, suppositories, pastes, creams, tablets, and foams. They contain acids, quinine, and tannin and a contraceptive base. Combination contraceptives unite both chemical methods that are used locally and mechanical methods; they include chemical (melting) caps, sponges, tampons saturated with spermicides, and douches that spray the vagina with spermicides. Biological contraceptives act on various parts of the reproductive process, for example, on the movement of sex cells through the reproductive system, on fertilization, and on the implantation of a fertilized ovum in the uterus. Biological contraceptives include highly active synthetic hormonal preparations for oral administration and certain biologically active nonhormonal agents, such as antihyaluronidases and antihistamines. The effectiveness of biologically active nonhormonal agents has not yet been sufficiently proved.

Oral and intrauterine contraceptives are widespread. Oral contraceptives have various mechanisms of action. The majority of highly active synthetic hormonal preparations must be taken daily for 21 days starting on the fifth day of the menstrual cycle in order to be almost 100 percent effective. Oral contraceptives have been developed that are effective when taken after presumed fertilization. In many women these contraceptives may produce bloody discharge, vomiting, and nausea. These reactions, however, are usually temporary and do not necessitate discontinuing the preparations. Oral contraceptives must be used only under a physician’s supervision. It is not recommended that they be used for more than six months consecutively because of possible complications.

Intrauterine contraceptives come in various sizes and shapes, for instance, rings, loops, and spirals. They are made of various materials, such as stainless steel and polymers. Insertion is into the uterine cavity, where the contraceptive is left as long as one year. The mechanism of intrauterine contraceptives is not sufficiently clear. Menstrual cycle irregularities, pain, and inflammatory diseases sometimes occur with their use.

Prolonged use of any contraceptive is detrimental to health, and it is necessary to change the contraceptive periodically.

V. I. ALIPOV