Combined Oral Contraceptives

Introduction

Most COCs contain the oestrogen ethinyl estradiol (EE) and a progestin (e.g. norethisterone, levonorgestrel, drospirenone). There are different formulations of COCs.

  • Monophasic COCs have the same dose of oestrogen and progestin throughout the pill pack.
  • Biphasic, triphasic and quadriphasic pill packs mimic the oestrogen and progesterone levels during a menstrual cycle.

NOTE:

  • COCs containing levonorgestrel and norethisterone have been used for many years and are associated with a lower risk of VTE than other COCs.
  • Drospirenone is structurally related to spironolactone; it has progestogenic, antiandrogenic, and anti-mineralocorticoid activity.
    • There is no evidence that a certain type of progestin in a COC formulation is any more effective in treating hyperandrogenic symptoms, such as acne or hirsutism, than another type.
    • In patients with conditions requiring chronic therapy with medications that may increase potassium, monitor serum potassium during the first treatment cycle and periodically thereafter if patient begins medication or develops a condition that increases risk for hyperkalaemia.



Indications

COCs is used for

NOTE: The contraceptive use should be considered along with WHO Medical Eligibility Criteria for Contraceptive Use.



Precautions

Breastfeeding

  • Oestrogens may decrease milk supply.
  • WHO medical eligibility criteria for contraceptive use advises delaying use of oestrogen-containing methods until 6 months postpartum for those who are primarily breastfeeding because of the importance of breastfeeding on infant health in low-resource settings.

Postpartum

  • Delay use until at least 3-6 weeks postpartum due to VTE risk

Smoking

Surgery

  • Where prolonged immobilisation is expected

Uncontrolled hypertension



Contraindications

  • Breast cancer (current or recent)
  • Known ischemic heart disease
  • Migraine with aura - due to an increased risk of stroke
  • History of stroke
  • History of venous thromboembolism (VTE)
  • Severe (decompensated) cirrhosis



Regimen

Most COCs are available as 28-day regimens, where active tablets are taken for 21, 24 or 26 days followed by inactive use. A hormone-free interval <7 days is thought to reduce the incidence of hormone withdrawal symptoms and, in some cases, it may increase contraceptive effectiveness by further suppressing ovarian.

NOTE:

  • Low-dose oestrogen COCs (e.g. ethinyl estradiol 20 mcg) appear to be as effective as standard dose (e.g. ethinyl estradiol 30-35 mcg), with a slightly higher incidence of breakthrough bleeding, especially at first.
  • COCs containing 50 mcg of ethinyl estradiol should generally not be used for contraception but are available for acute treatment of uterine bleeding.



When to Start for Contraception

A woman can start using COCs any time she wants if it is reasonably certain she is not pregnant.

  • For immediate contraception, start with an active pill within the first 5 days of your period starting.
  • If you start active pills after this, use additional contraceptive methods until you have taken active pills for 7 days.



What to Expect

While taking inactive pills, a withdrawal bleed (similar to a period) should start. However, sometimes this may not occur. Continue taking the pills as normal but consider the possibility of pregnancy if the pill has not been taken correctly or if 2 withdrawal bleeds in a row are missed.

Irregular bleeding or spotting is common at first but this usually settles down after 2-3 months.



When is It Less Effective

Effectiveness may be reduced by



Summary

While oral contraceptives are highly effective at preventing pregnancy, it is important to remind patients that they do not protect against sexually transmitted infections (STIs). Barrier methods, such as condoms, remain necessary for STI prevention.

  • The effectiveness of oral contraceptives can be significantly compromised by certain medications, such as carbamazepine, phenytoin and rifampicin.



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