What are monthly injectables?
Monthly injectables contain 2 hormones—a progestin and an estrogen—like the natural hormones progesterone and estrogen in a woman’s body. (Combined oral contraceptives also contain these 2 types of hormones.)
Also called combined injectable contraceptives, CICs, the injection.
Information in this chapter applies to medroxyprogesterone acetate (MPA)/estradiol cypionate and to norethisterone enanthate (NET-EN)/estradiol valerate. The information may also apply to older formulations, about which less is known.
MPA/estradiol cypionate is marketed under the trade names Ciclofem, Ciclofemina, Cyclofem, Cyclo-Provera, Feminena, Lunella, Lunelle, Novafem, and others. NET-EN/estradiol valerate is marketed under the trade names Mesigyna and Norigynon.
Work primarily by preventing the release of eggs from the ovaries (ovulation).
How Effective?
Effectiveness depends on returning on time: risk of pregnancy is greatest when a woman is late for an injection or misses an injection.
As commonly used, about 3 pregnancies per 100 women using monthly injectables over the first year. This means that 97 of every 100 women using injectables will not become pregnant.
When women have injections on time, less than 1 pregnancy per 100 women using monthly injectables over the first year (5 per 10,000 women).
Return of fertility after injections are stopped: an average of about one month longer than with most other methods (see Question 11).
Protection against sexually transmitted infections (STIs): none
Why Some Women Say They Like Monthly Injectables
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Do not require daily action
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Are private: no one else can tell that a woman is using contraception
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Injections can be stopped at any time
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Are good for spacing births
Side Effects, Health Benefits, and Health Risks
Side Effects
(see Managing Any Problems)
Some users report the following:
Changes in bleeding patterns including:
– Lighter bleeding and fewer days of bleeding
– Irregular bleeding
– Infrequent bleeding
– Prolonged bleeding
– No monthly bleeding
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Weight gain
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Headaches
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Dizziness
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Breast tenderness
Known Health Benefits and Health Risks
Long-term studies of monthly injectables are limited, but researchers expect that their health benefits and health risks are similar to those of combined oral contraceptives (see Combined Oral Contraceptives, Health Benefits and Health Risks). There may be some differences in the effects on the liver, however (see Question 2).
Correcting Misunderstandings
(see also Questions and Answers)
Monthly injectables:
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Can stop monthly bleeding, but this is not harmful. It is similar to not having monthly bleeding during pregnancy. Blood is not building up inside the woman.
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Are not in experimental phases of study. Government agencies have approved them.
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Do not make women infertile.
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Do not cause early menopause.
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Do not cause birth defects or multiple births.
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Do not cause itching.
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Do not change women’s sexual behavior.
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