starting the progestogen only pill

Last edited 03/2020 and last reviewed 03/2021

• women can start the POP up to Day 5 of the menstrual cycle without the need for additional contraceptive precautions; thereafter 48 hours of additional precautions are require
  
  
• when quick starting POP following a risk of pregnancy, a pregnancy test is advised no sooner than 3 weeks after the most recent episode of unprotected sexual intercourse (UPSI)
  
  
• after pregnancy the woman may restart POP immediately
  
  
• when starting after either Day 5 of the menstrual cycle, Day 5 post-abortion, or Day 21 postpartum, consideration of EC and a pregnancy test >=3 weeks after the most recent episode of UPSI may be required if there has been a risk of pregnancy
  
  
• contraceptive efficacy may be reduced if pills are missed (more than 3 hours late*), malabsorbed or with enzyme inducing drugs (have an effect for up to 8 weeks from discontinuation). An alternative contraceptive method should be used during the period of risk and for 48 hours afterwards
  
  
• if starting the progestogen only pill after a combined oral contraceptive then the progestogen only pill should be commenced immediately after the last combined pill has been taken and not at the end of the 7 pill free days
  
  
  • if starting POP after combined hormonal contraceptive pill (CHC)
    
    

• Timing of initiation	Need for additional precautions after starting	Additional information
  Day 1-2 of HFI (hormone free interval)	No	Day 1 is the optimal time to switch
  Day 3-7 of HFI OR week 1 following HFI	Yes (48 hours). If UPSI has occurred after Day 3 of HFI advise continuing the CHC method for at least 7 days	If CHC cannot be continued, switch to POP immediately and consider the need for EC and PT
  Week 2-3 of CHC use	No, providing the method has been used consistently and correctly (i.e. at least 7 consecutive pills taken or 7 days of patch or ring use prior to switching)	There is evidence to suggest that taking hormonally active pills for 7 consecutive days prevents ovulation in the subsequent 7 days (2)

*Traditional POPs have a 3 hour time window in which to be taken each day. However desogestrel (DSG) pills may have potential benefits over traditional POPs because ovulation is inhibited in up to 97% of cycles and they have a 12-hour window for missed pills (1).

• traditional POPs only suppress ovulation in approximately 50% of cycles. Therefore if more than 27 hours have elapsed between pills there is a risk that the contraceptive effect of the cervical mucus will be lost and additional precautions will be required to avoid pregnancy. However, ovulation suppression is maintained in DSG pill users who take their pills up to 12 hours late

Reference:

• FRSH (March 2015). Progestogen-only pills.
• FSRH (February 2019). Progestogen-only pills.