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Emergency contraception (EC), or emergency postcoital contraception, are birth control measures that may be used after sexual intercourse to prevent pregnancy.

Forms of EC include:

  • Emergency contraceptive pills (ECPs)—sometimes simply referred to as emergency contraceptives (ECs) or the "morning-after pill"—are drugs intended to disrupt or delay ovulation or fertilization, which are necessary for pregnancy (contraceptives).<ref name="Leung 2010">{{#invoke:Citation/CS1|citation

|CitationClass=journal }}</ref><ref name="Gemzell-Danielsson 2010">{{#invoke:Citation/CS1|citation |CitationClass=journal }}</ref><ref name="Trussell 2011">{{#invoke:citation/CS1|citation |CitationClass=book

}} p. 121:
Mechanism of action
Copper-releasing IUCs
When used as a regular or emergency method of contraception, copper-releasing IUCs act primarily to prevent fertilization. Emergency insertion of a copper IUC is significantly more effective than the use of ECPs, reducing the risk of pregnancy following unprotected intercourse by more than 99%.2,3 This very high level of effectiveness implies that emergency insertion of a copper IUC must prevent some pregnancies after fertilization.
Emergency contraceptive pills
To make an informed choice, women must know that ECPs—like the birth control pill, patch, ring, shot, and implant,76 and even like breastfeeding77—prevent pregnancy primarily by delaying or inhibiting ovulation and inhibiting fertilization, but may at times inhibit implantation of a fertilized egg in the endometrium. However, women should also be informed that the best available evidence indicates that ECPs prevent pregnancy by mechanisms that do not involve interference with post-fertilization events.
ECPs do not cause abortion78 or harm an established pregnancy. Pregnancy begins with implantation according to medical authorities such as the US FDA, the National Institutes of Health79 and the American College of Obstetricians and Gynecologists (ACOG).80
Ulipristal acetate (UPA). One study has demonstrated that UP can delay ovulation.81... Another study found that UPA altered the endometrium, but whether this change would inhibit implantation is unknown.82
p. 122:
Progestin-only emergency contraceptive pills. Early treatment with ECPs containing only the progestin levonorgestrel has been show to impair the ovulatory process and luteal function.83–87
p. 123:
Combined emergency contraceptive pills. Several clinical studies have shown that combined ECPs containing ethinyl estradiol and levonorgestrel can inhibit or delay ovulation.107–110
</ref>
  • Intrauterine devices (IUDs)—usually used as a primary contraceptive method, but sometimes used as emergency contraception.<ref name="Trussell 2011"/>

Emergency contraception sections
Intro   Emergency contraceptive pills   Intrauterine device  As regular contraception  History  Relationship to high risk sex and abortion  EC and sexual assault  Mechanism of action  See also  References  External links  

PREVIOUS: IntroNEXT: Emergency contraceptive pills
<<>>

Journal::first    Title::author    Pages::pills    Volume::issue    Trussell::women    After::location

{{#invoke:Infobox|infobox}}

Emergency contraception (EC), or emergency postcoital contraception, are birth control measures that may be used after sexual intercourse to prevent pregnancy.

Forms of EC include:

  • Emergency contraceptive pills (ECPs)—sometimes simply referred to as emergency contraceptives (ECs) or the "morning-after pill"—are drugs intended to disrupt or delay ovulation or fertilization, which are necessary for pregnancy (contraceptives).<ref name="Leung 2010">{{#invoke:Citation/CS1|citation

|CitationClass=journal }}</ref><ref name="Gemzell-Danielsson 2010">{{#invoke:Citation/CS1|citation |CitationClass=journal }}</ref><ref name="Trussell 2011">{{#invoke:citation/CS1|citation |CitationClass=book

}} p. 121:
Mechanism of action
Copper-releasing IUCs
When used as a regular or emergency method of contraception, copper-releasing IUCs act primarily to prevent fertilization. Emergency insertion of a copper IUC is significantly more effective than the use of ECPs, reducing the risk of pregnancy following unprotected intercourse by more than 99%.2,3 This very high level of effectiveness implies that emergency insertion of a copper IUC must prevent some pregnancies after fertilization.
Emergency contraceptive pills
To make an informed choice, women must know that ECPs—like the birth control pill, patch, ring, shot, and implant,76 and even like breastfeeding77—prevent pregnancy primarily by delaying or inhibiting ovulation and inhibiting fertilization, but may at times inhibit implantation of a fertilized egg in the endometrium. However, women should also be informed that the best available evidence indicates that ECPs prevent pregnancy by mechanisms that do not involve interference with post-fertilization events.
ECPs do not cause abortion78 or harm an established pregnancy. Pregnancy begins with implantation according to medical authorities such as the US FDA, the National Institutes of Health79 and the American College of Obstetricians and Gynecologists (ACOG).80
Ulipristal acetate (UPA). One study has demonstrated that UP can delay ovulation.81... Another study found that UPA altered the endometrium, but whether this change would inhibit implantation is unknown.82
p. 122:
Progestin-only emergency contraceptive pills. Early treatment with ECPs containing only the progestin levonorgestrel has been show to impair the ovulatory process and luteal function.83–87
p. 123:
Combined emergency contraceptive pills. Several clinical studies have shown that combined ECPs containing ethinyl estradiol and levonorgestrel can inhibit or delay ovulation.107–110
</ref>
  • Intrauterine devices (IUDs)—usually used as a primary contraceptive method, but sometimes used as emergency contraception.<ref name="Trussell 2011"/>

Emergency contraception sections
Intro   Emergency contraceptive pills   Intrauterine device  As regular contraception  History  Relationship to high risk sex and abortion  EC and sexual assault  Mechanism of action  See also  References  External links  

PREVIOUS: IntroNEXT: Emergency contraceptive pills
<<>>