birth control

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Voluntary prevention of conception by a man or a woman through the use of contraceptive techniques.
• noun A contraceptive technique.

from the GNU version of the Collaborative International Dictionary of English.

• noun the act or process of deliberately limiting the number of one's children born, especially by preventing conception.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Voluntary control of the number of children conceived, especially by the planned use of contraception.
• noun Any technique used to prevent the birth of a child (such as abortion or preventing conception).

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun limiting the number of children born