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.
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