The progestogen-only pill (POP) is used to prevent pregnancy without causing the adverse effects of estrogen.
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The POP is very popular for several reasons:
- It has a high efficacy of 94 percent, though this is lower than that of the combined oral contraceptive pill
- It contains less progestogen than the combined oral contraceptive and no estrogen at all
- It is independent of the act and timing of sexual intercourse
- It is safe for use during lactation because it does not suppress breast milk production
- It can be used at any age
- It can be used by women who have contraindications to the use of estrogen, such as those who have:
- Past or current venous thromboembolism (VTE) such as pulmonary embolism or calf deep vein thrombosis
- Past or current arterial disease such as myocardial infarction or cerebrovascular accidents (strokes)
- Past or current breast cancer
- Hypertension which is only moderately or poorly controlled
- Diabetes, especially when of 20 years or more, or with complications
- A habit of smoking, even in women over 35 years, who smoke 15 or more cigarettes a day
- Have the prospect of being immobilized following major surgery
- Are in the first month postpartum, especially if lactating
- POP can be used by women who are on the combined oral contraceptives currently but have crossed 35 years, or exhibit contraindications to estrogen use, such as smoking.
- It reduces menstrual flow and dysmenorrhea in many women
- It can produce amenorrhea in many women
- It can be used for post-coital or emergency contraception
Emergency contraception with POP should be taken within 72 hours of intercourse, and will prevent or delay ovulation. It does not usually prevent or disrupt implantation. Its efficacy wanes with increasing delay in taking the medication after intercourse. The woman will also suffer from vomiting within 2 hours of taking the drug, and increasing body weight.
Menstrual conditions can be improved by the use of POP. Continuous, rather than cyclic, use gives the additional benefit of inducing amenorrhea.
Such indications include:
- Migraines associated with menstruation
- Premenstrual syndrome
- Irregular menses
- Iron-deficiency anemia
- Flares of rheumatoid arthritis associated with certain times of the menstrual cycle
- Coagulation defects linked to the menstrual cycle
The POP is not the perfect contraceptive. Disadvantages include the following:
- For one thing, it has to be taken daily at almost exactly the same time, so that its efficacy depends largely upon the user’s memory. The newer POP containing desogestrel offers a margin of 12 hours in contrast to the three-hour grace period earlier available with conventional POPs.
- The POP cannot prevent sexually transmitted infections (STIs).
- Women on liver enzyme-inducing drugs such as phenytoin or barbiturates, or the herbal St. John’s wort, cannot expect reliable contraception with POPs.
- Regular menstruation cannot be expected. Menstrual abnormalities are almost universal, such as irregular bleeding, menorrhagia, amenorrhea, or extremely light spotting, especially for the first few months.
- It can cause other hormonal adverse effects such as:
- Breast tenderness or enlargement
- Weight gain
- Mood changes especially depression
- Decreased sex drive
- Development of follicular ovarian cysts due to abnormal follicle maturation. Such cysts are usually not symptomatic, and are self-limited.
- A small increase in the risk of breast cancer
- Increased risk of ectopic pregnancy if a woman on the POP conceives
- It is contraindicated, unless no other method of contraception is possible, in women with
- Past or current breast cancer
- Severe cirrhosis or hepatic tumors
- Current cerebrovascular or cardiovascular disease, especially with the newer POP such as desogestrel
- Factors which increase the risk of VTE, in the case of desogestrel or drospironene
- Women with systemic lupus erythematosus (SLE) who test positive for antiphospholipid antibodies
- Those on certain medications such as anticonvulsants or antiretroviral therapy, or antibiotics, which induce liver enzymes
Reviewed by Afsaneh Khetrapal BSc (Hons)