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Reference.org
Combined injectable birth control
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<p>Combined injectable contraceptives (CICs) are a form of <a href="/facts/Hormonal_contraception/xVw5DPGT">hormonal birth control</a> for women. They consist of monthly <a href="/facts/Injection_(medicine)/fvkH58gk">injections</a> of combined formulations containing an <a href="/facts/Estrogen_(medication)/mSKFraNu">estrogen</a> and a <a href="/facts/Progestin/8xMJYV3A">progestin</a> to prevent <a href="/facts/Pregnancy/vEKYGpep">pregnancy</a>. </p><p>CICs are different from <a href="/facts/Progestogen-only_injectable_contraceptive/mH8DwRYA">progestogen-only injectable contraceptives</a> (POICs), such as <a href="/facts/Depot_injection/wkVMHHdB">depot</a> <a href="/facts/Medroxyprogesterone_acetate/q6XACYYp">medroxyprogesterone acetate</a> (DMPA; brand names Depo-Provera, Depo-SubQ Provera 104) and <a href="/facts/Norethisterone_enantate/GrwqPRsn">norethisterone enantate</a> (NETE; brand name Noristerat), which are not combined with an estrogen and are given once every two to three months instead of once a month. </p><p>Hormonal contraception works primarily by preventing ovulation, but it may also thicken the cervical mucus inhibiting sperm penetration. Hormonal contraceptives also have effects on the endometrium, that theoretically could affect implantation. </p>