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

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Veset kavua for 40 day interval

16 November, 2015


Ever since I stopped taking birth control pills, my cycles have been exactly 40 days (and in the same onah) – this has happened twice so far. If this happens next time, does that mean I've established a veset kavua?

I'm asking because prior to taking birth control pills my cycles were 31–32 days. 40 days is considered abnormally long (but is common in the short–term after stopping birth control) and may be problematic in terms of fertility. Therefore does it really "count' as a veset kavua even though having 40 day cycles is not normal, is undesirable and will hopefully only be temporary?


Yes, if you have a third consecutive cycle of forty days, then you will have established a veset kavua.  As you note, this is common in the short term after stopping birth control.  Even so, it establishes a veset, which can be uprooted when your body changes its pattern.

Please note that according to some authorities, cycles up to 42 days can be normal; thus it may be premature to worry.

Please write back with any further questions.

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