Thank you for your medical query at AskTheDoctor.com
I understand your concern.
Yes, Plan B works by delaying the ovulation and in most cases the periods can be delayed by 5-7 days.
This happens because the environment and mucus layers are completely changed and the hormone levels immediately drop down on the consumption of the pill. It takes some time to come back to the pre-pill hormonal levels and this causes the delay.
Hope this was helpful,
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