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

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I track ovulation. Do I need to keep yom hachodesh & onah beinonit?

4 January, 2023
Question:

Do I need to observe day 30/31 if I tracked my ovulation and know my period is not expected in these days?


Answer:

Thank you for reaching out to us.

If you have consistently tracked your ovulation for at least three months in a row, so that you have established a minimum interval between ovulation and the onset of flow, then this has halachic weight. If the day of the month and onah beinonit occur before the earliest time you would expect your period based on ovulation, you are exempt from observing them.

Also, we follow the view that a woman whose flow consistently (three times consecutively) begins after day 31 of her cycle need not observe the onah beinonit or day of the month, but only the interval. If this is true in your case, then you will not need to observe those days for as long as this pattern persists.

We hope that this is clear. Please be in touch with any further questions.

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