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** How do birth control pills work? **

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Originally Published: May 18, 1995 - Last Updated / Reviewed On: April 13,
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How do birth control pills work?


Dear Woman,

Birth control pills prevent pregnancy through several mechanisms, mainly by
stopping ovulation. If no egg is released, there is nothing to be
fertilized by sperm, and the woman cannot get pregnant. Most birth control
pills contain synthetic forms of two female hormones: estrogen and
progestin. These synthetic hormones stabilize a woman's natural hormone
levels, and prevent estrogen from peaking mid-cycle. Without the estrogen
bump, the pituitary gland does not release other hormones that normally
cause the ovaries to release mature eggs.

Specifically, synthetic estrogen in the pill works to:

· Stop the pituitary gland from producing follicle stimulating hormone
(FSH) and luteinizing hormone (LH) in order to prevent ovulation.
· Support the uterine lining (endometrium) to prevent breakthrough
bleeding mid-cycle.

Meanwhile, synthetic progestin works to:

· Stop the pituitary gland from producing LH in order to prevent egg
· Make the uterine lining inhospitable to a fertilized egg.


how do birth control pills work

How Does the Birth Control Pill Work?


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** How Does the Birth Control Pill Work? **

From Tracee Cornforth, former Guide

Updated July 17, 2009 Health's Disease and Condition content is reviewed by the Medical
Review Board

*Question: *How Does the Birth Control Pill Work?
*Answer: *Birth control pills, or oral contraceptives, contain hormones
that suppress ovulation. During ovulation an egg is released from the
ovaries, without ovulation there is no egg to be fertilized and pregnancy
cannot occur. There are 2 types of birth control pills -- the combined pill
and the Minipill. The combined pill contains both estrogen and progestin,
while the Minipill contains only progestin.

The progestin in the Minipill may prevent ovulation; however it may not do
this reliably each month. The Minipill works further by thickening the
mucous around the cervix and preventing sperm from entering the uterus. The
lining of the uterus is also affected in a way that prevents fertilized
eggs from implanting into the wall of the uterus. The Minipill is taken
every day. You may not have a period while taking the Minipill, if you do
have periods that means you are still ovulating and your risk for pregnancy
occuring is greater.

Combination birth control pills come in either 21 or 28-day packs. You take
one pill each day at the same time for 21 days. If you have a 21-day pack,
you stop taking birth control pills for 7 days at the end of the pack. If
you are taking a 28-day pack, you continue taking pills every day, the last
7 non-hormonal pills serve as a reminder


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