Nishmat's Women’s Health and HalachaIn memory of Chaya Mirel bat R' Avraham

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Calculating onot based on ovulation

15 June, 2017


I am using an ovulation kit to track my cycles. Though I do not have a veset kavua, I do know that I will not be getting my period on the days of veset haflaga and beinonit, but rather a few days later (as I ovulated around day 19 of my cycle). Do I still need to keep those onot? May I use the ovulation day to calculate an onat prisha?


A woman cannot base her veset calculations on her time of ovulation, since the duration of the luteal phase may vary and ovulation is long before the onset of bleeding.  Thus, you should observe your vesatot as usual.

If, however, you have at least three consecutive cycles longer than thirty days in length, you may observe only the interval day, and omit the onah beinonit and the day of the month.

Please feel free to get back to us with any further questions.

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