Oral Contraceptive Pill

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Oral Contraceptive Pill

(Combined oral contraceptive)

  • contain ethinyloestrodial + a progesterone (e.g. desogestrel, gestodene, norgestimate)
  • 50% of women in 20s use it

Preparation

  • monophasic (21 identical tablets + 7 pill-free days)
  • biphasic (progesterone / oestrogen ratio alters)
  • Every-Day (21 active tablets + 7 dummy ones)

Using

  • 21 consecutive days + 7 days pill free / dummy pills
  • forgotten dose as soon as remembered
  • if >12 hours late then barrier contraception needed for next 7 days
    • continue straight to next packet if it finishes within this period

Mechanism of Action

  • oestrogen inhibits FSH release
    • suppresses ovarian follicle development
  • progestogen inhibits LH release
    • prevents ovulation
  • progestogen alters cervical mucus
    • decreased passage of sperm
  • altered endometrium
    • reduced chance of implantation

Advantages

  • most reliable contraception after surgery
  • does not interupt sexual relations
  • regulates menstrual cycle
  • reduces dysmenorrhoea and menorrhagia
  • ? protective against endometrial and ovarian cancer

Disadvantages

  • no protection against STDs
  • interferes with lactation

Adverse effects

  • weight gain

  • nausea

  • mood change

  • hypertension (small proportion of women)

  • Venous thromboembolism, DVT, PE

    • mainly in women who smoke

  • Arterial thrombosis

  • precipitates / alters pattern of Migraine

  • increased incidence of Gallstones

  • increased risk cervical / breast cancer ?

  • x20 risk hepatic adenoma (but still vanishingly rare)

Contraindications

Interactions

 

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