Synchronized menstruation: does it really happen?

totally. i used to work with 30+ women, and they all went on the rag within a day or two of each other.

definitely in a dorm – a ton of my friends here all get their periods at the same time. it’s a little weird. something to do with the hormones.

Not for me. I’ve had the same female roommate for seven years and I have always been a week ahead of her.

Uncle Cecil seems to think so.

Yeah. I go to a girls school and I swear that the people in one dorm always get it at the same time.

yes. It’s weird, because whenever it’s that time of the month my friends also are on it.

Also, I’d like to lead this question into another related question: do your boobs get bigger a week or so before you go on your period?

@Drawkward but did you read tthe update?

@faye Huh. Didn’t notice that. It’s been a while since I read that, anyways.

This was originally observed in paper written by Martha McClintock in 1971. Since then, scientists have not had very consistent success replicating the study. An analysis of this published in 2006 finds:

Although more than thirty years of intensive investigation have passed since McClintock first published results on menstrual synchrony, there is still no conclusive evidence for the existence of this phenomenon. Indeed, a growing body of nullresult studies, critiques of menstrual synchrony studies, and the lack of convincing evolutionary explanations bring into question the existence of this phenomenon. This paper presents results of a study conducted over five consecutive months in Polish student dormitories. In 18 pairs and 21 triples of college-age women, menstrual synchrony was not found. Social interactions, considered the most important factor mediating the effect of menstrual synchrony, was unrelated to any difference in menstrual cycle onsets. Initial menstrual onset difference was influenced by woman’s body mass and menstrual cycle irregularity. These results provide further evidence that women do not synchronize their menstrual cycles.
from the journal Human Nature.

@holden: This seems to be true in some women:

The volume of the left and right breasts was measured daily in four nulliparous women during normal menstrual cycles and after the use of oral contraceptives. Breast volume increased significantly in the second half of both normal and contraceptive-controlled cycles.
from the British Medical Journal

@nikipedia thanks! I was becomming concerned about that.

Hmmm, well that always happened when i lived in the door (you could always tell because the hygiene trash boxes in the stalls were overflowing ewwwww). But currently I’m living in a house with my roommate and she’s consistently a week & a half ahead of me.

I feel like there was a study done on this where women lived together and whoever was the stinkiest or something ended up being the person everyone else synced too.

Being completely unscientific, with these two bits of information maybe we can say that in situations where everyone is closely packed and smelling each other (say, in a dorm or sorority building and not in a house with two women) then Aunt Rose decides to pull a one-stop-shop and give everyone their little gifts together.

Not only does it happen but Synchronized Menstruation is to debut as an official event at 2012 Olympics in London.

@AstroChuck awesome!

I hear they sync up like wireless routers.

No it’s defiantly false. If it were true. They would have killed all the men.

Doesn’t it have something to do with the moon?

Sometimes yes it does happen ive found in younger girls but it never happens with me and my mom, just me and my friends….
We all become the big bad witches for a week together lol. Sometimes it gets quite funny at how pissy we get at each other for stupid things that the next week we laugh about..

I have heard it happens so that the maximum number of females can become pregnant in the shortest amount of time. (if Mr.Caveman gets it on with 2 synchronized females on the same day, but then dies the next, there is still a chance that both of them will become pregnant. Propagation of the species and all that.)

@FutureMemory i heard it was because bitchiness loves company.

I wouldn’t be surprised if women used to sync up together all the time. Nowadays, with birth control, chemicals, processed food, etc. I wouldn’t be surprised if it happens a lot less often than it used to. My mother says that when she was in high school, she synced up with her sisters and her mother.

One thing I found interesting was how last year, the first month I lived with my roommate, she did sync up with me even though she was on birth control and I was not.