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Contraception

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A diaphragm (a type of physical barrier method) in its case, with a quarter added for scale.
Condom (rolled-up).

Contraception is the prevention of the fusion of gametes during or after sexual activity. The term contraception is a portmanteau of contra, which means against, and the word conception, meaning fertilization.[1] Contraception can occur both naturally and via artificial means in humans and in animals. Contraception can occur both naturally and via artificial means in humans.

Naturally occurring contraception

When a mother feeds her baby only with her breast milk, this tends to prevent the release of hormones that cause ovulation.[2] This occurs naturally, but it can also be manipulated as a method of birth control called the Lactational amenorrhea method.

Contraception as a form of birth control

The techniques of birth control can be classified by the stage of reproduction during which it is active. A form of birth control that prevents the sperm from fertilizing the egg is a contraceptive agent.[3][4] A form of birth control that acts after fertilization to prevent or interrupt the implantation of the embryo into the uterine lining is a contragestive agent.[5] After implantation has occurred, an agent that ends gestation by terminating the pregnancy is an abortifacient.[6][7] These mechanisms of action are not always mutually exclusive. One substance or device can have more than one potential effect depending upon when it is used. For example, while mifepristone is best known as an abortifacient, it can also function as a contragestive agent.[8] Likewise, the IUD can be used as a contraceptive or a contragestive depending upon when it is inserted.[9]

There are a variety of laws in many countries which prohibit or regulate the availability of contraceptive devices. The laws range from outright prohibition to prohibition of some forms of contraception, to minimum ages for availability, to whether a prescription is required, etc.

Types

Ortho Tri-cyclen, a brand of oral contraceptive, in a dial dispenser.

Contraceptives are devices, techniques, and methods used to prevent fertilization. Barrier contraceptives are devices that attempt to prevent pregnancy by physically preventing sperm from entering the uterus. Devices in common use include condoms, female condoms, cervical caps, and diaphragms. SILCS diaphragms are still in clinical testing.

Hormonal contraceptives inhibit female ovulation or fertilization. These include injectable[10] and oral contraceptives. The most common hormonal contraceptives are the combined oral contraceptive pill, commonly referred as "The Pill", which includes a combination of an estrogen and a progestin (progestogen), and the minipill that contains only synthetic progestogens and do not contain estrogen. Currently, hormonal contraceptive options are available only to females.

Sterilization is a permanent form of providing contraception using surgical techniques, such as tubal ligation for females and vasectomy for males, to alter the reproductive function of the sex organs.

Currently, research is underway to investigate surgical but temporary contraception to males as an alternative to permanent sterilization, which is difficult to reverse. Ultrasound is a potential heat-based contraceptive method involving the application of high-frequency sound waves to the testes, which can absorb the sound waves’ energy as heat, leading to temporary infertility.[11] Another reversible surgical contraceptive method under investigation is reversible inhibition of sperm under guidance (RISUG), which involves the injection of a polymer gel into the vas deferens. The polymer has a positive charge, and when negatively charged sperm pass through the vas deferens, the charge differential severely damages the sperm.[12]

Emergency contraceptives, or "morning-after pills", are drugs that disrupt ovulation or fertilization in order to prevent pregnancy taken after sexual intercourse. An IUD can also be used as an emergency contraceptive, if it is implanted early enough, although it has a contragestive effect when it is implanted later.[13][14][15]

In other animals

Contraception occurs naturally in non-human animals just as it does in humans. For example, the same hormonal effect of breastfeeding occurs both in humans and in chimpanzees.[16] Artificial contraception is now being considered as an alternative to hunting as a means of controlling the population of animals which overbreed.[17]

See also

References

  1. ^ [1] The American Heritage Medical Dictionary Copyright 2007, 2004, page 120.
  2. ^ [2] The Complete Book of Breastfeeding By Sally Wendkos, Sally Wendkos Olds, Laura Marks, Marvin Eiger Page 57
  3. ^ [3] Melloni's Pocket Medical Dictionary By June L. Melloni, Ida G. Dox, B. John Melloni, Gilbert M. Eisner, Published by Informa Health Care, 2003, page 86.
  4. ^ [4] Dorland's Illustrated Medical Dictionary. Philadelphia, PA: Elsevier Health Sciences. (2007). Retrieved May 26, 2009.
  5. ^ [5] The American Heritage Medical Dictionary, Houghton Mifflin Harcourt; Copyright May 2008. page 124.
  6. ^ [6] Melloni's Pocket Medical Dictionary By June L. Melloni, Ida G. Dox, B. John Melloni, Gilbert M. Eisner, Published by Informa Health Care, 2003, page 1.
  7. ^ [7] The American Heritage Medical Dictionary. Boston, MA: Houghton Mifflin. (2007)Retrieved May 26, 2009
  8. ^ [8] Contragestion and other Clinical Applications of RU 486, an Antiprogesterone at the Receptor, Etienne-Emile Baulieu Science, New Series, Vol. 245, No. 4924 (Sep. 22, 1989), pp. 1351-1357 Published by: American Association for the Advancement of Science Retrieved May 26, 2009.
  9. ^ [9] Emergency: Emergency Contraception Bobbi J. Morris, Cathy Young, Kathleen Kearney, The American Journal of Nursing, Vol. 100, No. 9 (Sep., 2000), p. 47 Published by: Lippincott Williams & Wilkins Retrieved May 26, 2009.
  10. ^ [10] Hendrick, Judith (1997). Legal aspects of child health care. Nelson Thomas. p. 102. ISBN 978-0-412-58320-9
  11. ^ Ultrasound as contraceptive
  12. ^ [11] Expanding Options for Male Contraception. Planned Parenthood Advocates of Arizona. August 8, 2011. Retrieved April 1, 2012.
  13. ^ [12] Contragestion and other Clinical Applications of RU 486, an Antiprogesterone at the Receptor, Etienne-Emile Baulieu Science, New Series, Vol. 245, No. 4924 (Sep. 22, 1989), pp. 1351-1357 Published by: American Association for the Advancement of Science Retrieved May 26, 2009.
  14. ^ [13] Ammer, Christine; Manson, JoAnn E, & Brigham, Elizabeth F. (2009). The Encyclopaedia of Women’s Health. Infobase Publishing. p. 312. ISBN 978-0-8160-7407-5.
  15. ^ [14] Emergency: Emergency Contraception Bobbi J. Morris, Cathy Young, Kathleen Kearney, The American Journal of Nursing, Vol. 100, No. 9 (Sep., 2000), p. 47 Published by: Lippincott Williams & Wilkins Retrieved May 26, 2009.
  16. ^ [15] The Evolution of human behavior: primate models By Warren G. Kinzey, American Anthropological Association. Meeting, American Association of Physical Anthropologists Page 84
  17. ^ [16] Popular Science- Birth Control for Animals: A scientific approach to limiting the wildlife population explosion By Rebecca Boyle
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