What Exactly Do Contraceptives Do?

What Exactly Do Contraceptives Do?

Taking a look at my Google Reader lately, it seems like contraception is getting more than its five minutes of fame in the news and media!  This shouldn’t be too surprising, especially when 99% of women in the United States report using some form of contraception in their lifetime (http://www.guttmacher.org/pubs/fb_contr_use.html).

Whether you are having a political debate or just seeing your doctor for a yearly physical, it’s important to have the facts on what options are available to you and how exactly they work to prevent pregnancy.  Generally, contraceptives can be categorized as a barrier method, hormonal method, sterilization, withdrawal, natural family planning, and abstinence.

Barrier Methods

Barrier methods include male and female condoms, diaphragms, cervical caps, and spermicide.  They prevent pregnancy by stopping sperm from reaching a woman’s uterus.  An added bonus is that male and female condoms can prevent the spread of STI/STD when used consistently and correctly.

Hormonal Methods

Hormonal methods are the most popular method of contraception in the United States.  Almost 1/3 of women who use contraceptives in this country choose the oral contraceptive pills as their method of choice.  However, there are lots of different methods available, including the pill, the patch, the vaginal ring, IUDs, and contraceptive implants.

The gurus of contraceptive technology, Dr. Robert Hatcher and Dr. James Trussell, created the great diagram shown below.  It breaks down how different hormonal contraceptive methods work to prevent pregnancy!



Sterilization is a popular contraceptive method for women who do not ever want to become pregnant (either again or ever).  Some methods are surgical, while others can be done in a doctor’s office.


Withdrawal, known formally as “coitus interruptus”, tries to prevent sperm from reaching the uterus.  Though it may be inexpensive, 20 out of 100 couples using this method for a year will get pregnant.  Not so effective!

Natural Family Planning

Natural family planning (NFP) includes a number of methods aimed at predicting fertile and non-fertile days in a woman’s cycle.  On fertile days, she should not have sex or use a barrier method if she does not want to become pregnant.  NFP methods require diligence, commitment, and attention to detail.  Even with all of this, 25 out of 100 couples will get pregnant if they used this method for a year.

Emergency Contraception

Emergency contraceptive (EC) methods are methods used after sex when the primary method may have failed, or not been used, and there is a risk for pregnancy.  Both EC methods available in the US, Plan B and ella, are progestin-only methods that work by delaying ovulation.  They will not terminate an existing pregnancy and are not the same as the medical abortion pill, RU-486.


Abstinence from vaginal sex is the only 100% effective method of preventing pregnancy!

And of course, I realize that not everyone wants or needs birth control for any number of reasons.  However, lots of these methods have potential benefits beyond pregnancy prevention so to learn more about available options, check out these great tools online!

Method Match

My Method

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