POP

• Overview:

  • Only contains progesterone
  • Taken continuously unlike the cyclical combined pills
  • More than 99% effective with perfect use, but 91% effective with typical use
  • Has far few contraindications and risks compared with the combined pill - only big contraindication is active breast cancer
• There are two types of POP to remember:

  • Traditional progestogen-only pill (e.g. Norgeston or Noriday)
  • Desogestrel-only pill (e.g. Cerazette)
• The traditional progestogen-only pill cannot be delayed by more than 3 hours. Taking the pill more than 3 hours late is considered a “missed pill”.
• The desogestrel-only pill can be taken up to 12 hours late and still be effective. Taking the pill more than 12 hours late is considered a “missed pill”.
• Traditional progestogen-only pills work mainly by:

  • Thickening the cervical mucus
  • Altering the endometrium and making it less accepting of implantation
  • Reducing ciliary action in the fallopian tubes
• Desogestrel works mainly by:

  • Inhibiting ovulation
  • Thickening the cervical mucus
  • Altering the endometrium
  • Reducing ciliary action in the fallopian tubes
• Starting POP:

  • Starting on day 1-5 of the menstrual cycle means the women is protected immediately
  • If started after, additional contraception is required for 48 hours
  • Takes 48 hours for the cervical mucus to thicken enough to prevent sperm entering the uterus
• The POP can be started even if there is a risk of pregnancy, as it is not known to be harmful in pregnancy. However, the woman should do a pregnancy test 3 weeks after the last unprotected intercourse.
• Changes to the bleeding schedule is one of the primary adverse effects of the progestogen-only pill. Unscheduled bleeding is common in the first three months and often settles after that. Where the irregular bleeding is persistent (for longer than 3 months), other causes need to be excluded (e.g. STIs, pregnancy or cancer).
• Approximately:

  • 20% have no bleeding (amenorrhoea)
  • 40% have regular bleeding
  • 40% have irregular, prolonged or troublesome bleeding
• Other side effects include:

  • Breast tenderness
  • Headaches
  • Acne
• There is also an increased risk of:

  • Ovarian cysts
  • Small risk of ectopic pregnancy with traditional POPs (not desogestrel) due to reduce ciliary action in the tubes
  • Minimal increased risk of breast cancer, returning to normal ten years after stopping
• A pill is classed as “missed” if it is:

  • More than 3 hours late for a traditional POP (more than 26 hours after the last pill)
  • More than 12 hours late for the desogestrel-POP (more than 36 hours after the last pill)

  The instructions are to take a pill as soon as possible, continue with the next pill at the usual time (even if this means taking two in 24 hours) and use extra contraception for the next 48 hours of regular use
• Episodes of diarrhoea or vomiting are managed as “missed pills”, and extra contraception (i.e. condoms) is required until 48 hours after the diarrhoea and vomiting settle.