Menstrual synchrony theory – Will women’s periods sync up?

Are you aware of women having their menstrual cycles syncing up over time when they are in close proximities to each other? There is a belief that this happens, and it’s widely known. However, like many other things, this is a controversial topic that many have been debating for some time. To help you know more, we will look at the menstrual synchrony theory in this article.

First, let’s take a brief look at the menstrual cycle.

To know your menstrual cycle, you would count from the very first day that the bleeding starts until the first day of your next period. This cycle could vary from twenty-one to thirty-five days, but it last for twenty-eight days on average. It actually occurs in four different phases which are the menses phase, follicular phase, ovulation phase, and luteal phase.

The menses stage is when the bleeding occurs. The average bleeding time is three to five days, but two to seven days is also considered normal. This is the phase that people focus on when talking about the synching of menstrual cycles. The follicular phase is when the follicles inside the ovaries start to mature and develop an egg. The estrogen levels will also increase and cause the uterus lining to thicken. After that, ovulation will occur, and the egg is released because of the rising level of the luteinizing hormone.

For the final phase, which is the luteal, the egg will be released out of the ovary and goes down to the fallopian tubes and inside the uterus. Pregnancy will occur if the egg gets fertilized and then attaches itself to the uterine wall. If not, the levels of the progesterone and estrogen hormones will drop and cause the thickened uterus lining to shed, and menstrual bleeding will start once again. Hormones will mediate this whole process from when menstruation starts to the beginning of your next period.

Menstrual Synchrony Theory – Will Women’s Periods Sync Up?

There have been many stories from women about periods syncing up, including family members, close friends, and college roommates. This has led to the common question above. The simple answer is that there is no foolproof evidence of this to date, but many researchers believe that it’s menstrual synchrony.

Menstrual synchrony, known also as the McClintock effect, is a so-called process where the onsets of women’s menstrual cycle becomes closer in time once they start to live together or maybe spend lots of time in close proximity. This basically means that their menstrual cycles start to sync up and their periods come at the same time.

Airborne chemical signals or pheromones have been believed to play a role in this occurrence because an individual can release them into the environment, and they will affect the behavior or physiology of others of the same species.

Martha McClintock was the first person to document this concept while doing a seminal research paper in the year 1971. For this research, 135 female students were observed while living in the same dormitory and it was discovered that the onset dates of their menstrual cycle synced up significantly. It is believed that this synchronization is caused by several mechanisms.

It is important to mention that some other researchers followed McClintock findings after replicating the research, but many did not find any evidence of the menstrual synchrony. There is a dispute here because women’s periods can be very inconsistent to sync up, especially when birth control is not used.

The prevailing theory is that the synchronicity of women’s period is at a level of chance because the variability of their cycle can lead to repeated convergences and consequent deviations, which might explain the synchrony theory. This means women might believe their periods sync up when they might only align randomly for a short time and is likely to come in and out of schedules which match-up.

One of the strongest arguments against the menstrual synchrony theory is that two females with different menstrual cycle lengths are never going to synchronize because the lengths of menstrual cycles vary from person to the next. They might menstruate simultaneously one month, but not the same the next month, and this difference could go on for even longer. This argument would prove that the synchrony is just a myth as the human bodies hardly adhere to schedules which are timed perfectly. Most females have irregular periods monthly, plus the regularity of their menstrual cycle will change at different phases of life. Therefore, two women might have cycles shifting to twenty-six or twenty-seven days if one with a twenty-five-day cycle lives together with another who has a twenty-eight-day cycle. In this case, synchronization could be possible.

There is no solid evidence to support the menstrual synchrony theory at the moment, but this doesn’t mean that the topic is closed. Women are still reporting their personal non-clinical experiences and researchers are looking further into the theory.

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