The disappearance of וסת קבוע and הרגשות

Question

At some point in history, Jewish women used to have very regularly scheduled Monthly cycles, and used to have some sensation that accompanied the onset of menstruation. Both of these play important roles in Halacha. The monthly cycle establishes what is called a וסת קבוע, which affects what days a woman has to take into account that her menstruation is about to begin. The sensation (הרגשה) is a Biblical prerequisite the absence of which prevents blood from creating ritual impurity, according to most opinions.

At some point in history, women stopped having both of these. The earliest discussion of the cessation of הרגשה that I have seen is in the שב יעקב, circa 1750. The Aruch HaShulchan (early 20th century) asserts that women still have הרגשה, they just don't know what it is well enough to recognize it, but this is just a different way in which it was lost (it became undetected).

Rav Yaakov Kaminetzky reported that when he was in Europe most women had regular Monthly cycles. Today, it is very rare, although apparently not unheard of, from what I have been told.

My question is - is there any Rabbinic speculation about why these changes, with significant Halachic ramifications and/or implications, occured when they did? Are they associated with any world events? Is there any metaphysical significance attributed to the changes?

Answer 1

This was raised in Europe already - see Taharas Yisrael I think. Note that the painful menstruation which woke women from sleep was much more common.

With higher percentages of body fat, they have more hormones perhaps.

Joking aside -

Perhaps steady low calorie diet when young puts the girl into Strong Pattern. Some women from poor countries such as Thailand kept their patterns even in USA.

This is based on small sample size.

Hormones in food - if ingested in quantity - can affect a cycle.

Answer 2

Here is a partial answer to your two part question. I have heard from the Rabbis I learnt shmattas with in the name of Rav Bic & Rav Menasheh Klein who both independently attributed the erratic vestos to the suddenly widespread use of electric lines.

Answer 3

Could it be the electric lights that affects the cycle?

This scientific paper discusses how lighting affects ovulation. Ovulation in turn usually precedes menstruation by a fixed number of days even in today's day and age.

This may explain why some women used to have their cycles linked to the day of the Jewish month; i.e. the cycle of the moon. Moonlight matters a lot more when you didn't have electric lighting.

Answer 4

There is little rabbinic speculation in an halachic context for why this changed but the standard explanation is that modern lighting and and nutrition have caused this change.

I know who had difficulties with cycles causing her to be a nidda too frequently. She was advised to use dimmer lights at night and no light at all when she slept and it worked.

I was also by a nurse who had volunteered for Doctors without Borders that in third world countries women's menstrual cycles and experiences are the same as they were in ancient times.

Answer 5

I am a Rabbi I speculate that the cycal is not set anymore

maybe becouse of feminism, since the woman stopped staying at home, or at the shtetal (some woman still have a set one) so through Menstrual synchrony (by meeting a lot of different woman that have different cycles daily) the set cycle got ruined see first comment above of @user6591