How Does Birth Control Work?

Julie Kirk
Woman discussing birth control option

There are many different birth control options to choose from. It is important to know how the various birth control methods work and their effectiveness. Learning this important information can help you make an informed decision on the birth control that's right for you.

Hormonal Birth Control Methods

There are a number of different forms of hormonal birth control available. The hormones in birth control that prevent pregnancy are estrogen, progesterone, or a combination of both. You can take this type of birth control orally, insert it into the uterus, implant it in the arm, receive it by injection, wear it and absorb it into the body, or insert it vaginally at the cervix area.

How Hormones Prevent Pregnancy

The hormones actually perform different functions in order to prevent pregnancy.

  • They will suppress the eggs in the ovaries from maturing, and ovulation will not occur. Therefore, no eggs will be released for the sperm to fertilize.
  • They can thin the lining of the uterus (endometrium) which will help prevent implantation of a fertilized egg.
  • They can thicken cervical mucus to make it more difficult for the sperm to reach the egg.

Types of Birth Contol That Contain Hormones

There are various types of birth control methods that contain hormones.

Birth Control Pill

Package of birth control pills

Most pills contain a combination of the synthetic forms of the hormones estrogen and progestin (progesterone). Different pills will have different doses of the hormones.

  • Take the birth control pill orally.
  • It is 99 percent effective and very reliable when taken correctly.
  • Doctors will prescribe certain pills depending on a woman's individual needs and if there are any risk factors involved.
  • After you take the pill for 10 consecutive days, it will become effective in preventing pregnancy.

There also is a progestin-only pill (the minipill) for women who are unable to take estrogen due to medical conditions such as breast cancer, blood clots, and liver disease. Nursing mothers can also take the minipill because it does not have any negative effects on breast milk.

Birth Control Implant

The birth control implant is a long-term contraceptive device that releases progestin to prevent pregnancy.

  • It is a small, thin plastic rod a doctor inserts in the inner part of the upper arm.
  • It is over 99 percent effective and lasts for 3 years.
  • It will be immediately effective only if inserted in the first five days of your cycle. Otherwise, you'll need back-up contraception for about a week.

Birth Control Injection

The birth control injection a safe and convenient form of birth control that contains progestin to prevent pregnancy.

  • A practitioner provides an injection in the arm every three months.
  • It is 94 percent effective in protecting against pregnancy.
  • If you receive the shot in the first seven days of your cycle, you will be protected immediately. If you receive it at any other time in your cycle, you will need a back-up form of contraception such as a condom for about a week after the injection.

Birth Control Patch

This form of birth control releases estrogen and progestin into your skin.

  • It is a small, thin, plastic patch placed directly on your abdomen, back, buttocks, or upper arm.
  • It is 91 percent effective.
  • Change the patch once a week for three weeks. Do not wear it on the fourth week so you will get your period.
  • If you apply the patch within the first five days of your period, you will be protected immediately. If you miss the five day window, you will need a back up form of birth control for about a week.

Birth Control Ring

This form of birth control releases estrogen and progestin to prevent pregnancy.

  • This birth control is a flexible, plastic ring a doctor inserts into the vagina at the cervix.
  • It is 91 percent effective.
  • Wear it for three weeks and remove on the fourth week, and you will have your period.
  • If you insert the ring within the first five days of your period, you will be protected immediately. If inserted at any other time of your cycle, you will need back up protection for one week.

IUDs

There are two types of IUDs (intrauterine devices), hormonal and hormone free. Both are small, t-shaped devices a doctor inserts into the uterus to serve as a long-term form of contraception.

Hormonal IUDs

This type of IUD releases progestin in order to prevent pregnancy.

  • It is made of plastic.
  • It is 99% effective.
  • It lasts three to five years depending on the IUD you choose.
  • If a doctor inserts it the first seven days of your cycle, it is effective immediately. If inserted at any other time, you'll need back-up contraception for about a week.

Hormone Free IUD

This type of IUD is a good option for women who can't or do not want to use a hormonal birth control.

  • It is made of copper.
  • The device continuously releases small amounts of copper into the uterine lining.
  • Sperm do not like copper which makes it virtually impossible for the sperm to reach the egg.
  • It is 99 percent effective.
  • This IUD can help protect against pregnancy for 10 years.
  • It is effective immediately upon insertion.
  • It is also used as a form of emergency contraception if inserted within five days of unprotected sex.

Barrier Methods

This type of birth control prevents sperm from entering the uterus. There are multiple types of barrier methods for birth control.

Male Condom

Packages of colorful condoms

This type of birth control is 98 percent effective when used correctly and is the best way to protect against sexually transmitted diseases.

Diaphragm

The diaphragm is a silicone, flexible cup inserted in the vagina that covers the cervix. It is important to use spermicide with the diaphragm. It is 94 percent effective if used correctly. It needs to be fitted by your doctor and lasts for two years.

Spermicide

This type of birth control comes in gel, cream, or suppository form. It is placed in the vagina before intercourse and prevents sperm from penetrating through to the uterus. Spermicides alone have a 28 percent failure rate but when used in combination with another form of birth control, such as a diaphragm, it is highly effective.

Consider Doubling Up

For your own protection, doubling up on contraception is always a good idea. The use of a condom with any of the aforementioned birth control will not only provide additional protection against pregnancy but it will help prevent the transmission of sexually transmitted diseases.

How Does Birth Control Work?