Theory:

Hormonal methods:
Hormonal preparations are in the form of pills or tablets (contraceptive pills). Only females can use these pills. The pills contain either a progesterone or progesterone-estrogen combination.
 
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Hormonal pills
  
The hormones acts by:
  
aStopping ovulation (the release of an egg from the ovary)
 
b. Inhibits implantation by altering the uterine endometrium
 
c. Alters the quality of cervical mucus to prevent the entry of sperms
 
d. Inhibits the motility and secretory activities of fallopian tubes
 
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Statistics of the usage of birth control pills
Intra-Uterine Devices (IUDs):
Intra-uterine devices (IUD) are contraceptive devices inserted into the uterus. These devices are used only by the female. Doctors or expert nurses insert these into the uterus through the vagina. There are three synthetic devices commonly used in India, which include:
 
1. Non-medicated IUDs, which include Lippe's loop
 
2. Copper releasing IUDs or Copper-T
 
3. Hormone releasing IUDs
  
Lippe's loop is made of inert plastic, and Copper-T is made of copper that is non-irritant.
 
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Lippe's loop
 
These IUDs can remain inside the female's reproductive tract for \(3\)years. These reduce the sperm fertilising capacity, suppress sperm motility and prevents implantation (by making the cervix hostile to the sperms). It also helps to give adequate time intervals between pregnancies. IUDs inserted into the uterus irritate the uterus.
 
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The Copper-T tube inside the female reproductive tract
Surgical methods:
Sterilisation / surgical contraception are terminal methods that prevent any pregnancy. The method blocks the gamete transport and thus prevents fertilisation. Sterilisation procedure in the male is known as vasectomy (ligation of vas deferens).
 
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Vasectomy
 
In females, it is known as tubectomy (ligation of fallopian tubes).
 
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Tubectomy
  
The following video shows the different contraceptive methods:
  
 
Important!
Unwanted pregnancies can also be removed by surgery. These could be misused by people who do not want a specific child, like in the case of illegal sex-selective abortions of female foetuses. In a healthy society, the female-to-male sex ratio must be maintained.
Reference:
https://upload.wikimedia.org/wikipedia/commons/1/1d/Pilule_contraceptive.jpg
https://www.flickr.com/photos/washington_area_spark/8384238867
https://www.flickr.com/photos/mitopencourseware/4796306235
https://www.flickr.com/photos/_graphs/4638356573
https://commons.wikimedia.org/wiki/File:Vasectomy_diagram-en.svg
https://www.youtube.com/watch?v=ziSKvk93kPw