Menstrual Synchronization: Do The Periods Of Women Who Live Together Synchronize?

Menstrual synchronization between women living together is a popular belief that, 50 years after the appearance of the study that made this claim, still persists. However, this hypothesis has not been verified. Find out more here on this topic.

Menstrual synchronization is a popular myth that we have heard about for over fifty years. This idea was introduced by psychologist Martha McClintoc, following a study she herself carried out with women living together in a student residence. This study was even published in the scientific journal Nature .

Her theory was as follows: in women who live together or spend a lot of time together, there is a synchronization of periods over time. According to the psychologist, her study confirmed her theory and pheromones are responsible for menstrual synchronization.

Menstrual synchronization and pheromones

Pheromones are a kind of ectohormones that have been studied in mice and still other mammals. They play an important role in behavior and communication between individuals of the same species.

In the case of humans, the link between communication and pheromones has not been strictly verified. At the moment, therefore, it is not possible to conclude that the theory of menstrual synchronization responds to a hormonal mechanism. Further studies to affirm or refute this theory are needed.

How is a normal menstrual cycle regulated?

Nowadays, we know a lot about female physiology. This topic has been studied in depth and continues to be studied.

From birth, eggs are found in the ovaries and they remain there until the onset of puberty. From the changes associated with puberty, and throughout the fertile stage, once a month a woman will experience a process called the menstrual cycle or menstruation. This menstrual cycle is what is more commonly known as a “period”.

Regulation of menstrual cycles occurs through the stimulatory and inhibitory effects of hormones found in the brain and in the ovaries. The hypothalamic hormones involved (LH and FSH) are released periodically by the hypothalamus (an area of ​​the brain) and have a direct action on the ovaries.

The result of this hormonal secretion is as follows: the ovary responds to this stimulus by releasing a mature egg as well as steroid hormones different from those released by the hypothalamus. The released egg will be ready to be fertilized ; the encounter with a healthy sperm will give a zygote.

This stage will also be characterized by the enlargement of the endometrium, the inner layer of the uterus. If the egg is fertilized, the large endometrium will implant itself a few days later. Otherwise, there will be no fertilization and the endometrium will undergo certain changes that will cause it to detach.

This process that we have just described will be repeated every 28 or 35 days. By convention, the first day of menstruation is the first day of the cycle. It is from this day that we determine the most fertile days, for example.

What do we know about irregular periods?

Usually, menstrual cycles vary little between the ages of 20 and 40. The years between these two ages are characterized by better regularity of menstrual cycles. The greatest changes in menstrual cycles therefore occur before the age of 20 and after the age of 40: menstrual cycles are more frequently irregular.

Age is not the only factor that can explain menstrual irregularities. There are others. For example, during adolescence, irregular menstrual cycles are common because the hormonal system is not yet mature enough. On the side of women over 40 and premenopausal, irregular menstrual cycles can be explained in particular by the depletion of the ovarian reserve.

Stress, obesity, low weight, thyroid problems, medication, and certain illnesses such as diabetes are other factors that can explain menstrual irregularities. The changes can be one-off or last for several months.

Scientific evidence on menstrual synchronization is inconclusive

In 2006, Ziomkiewicz, professor at Jagiellonian University , carried out a study similar to that of McClintock. The result was this: the rules of the participants did not synchronize. We can then say that, for the moment, there is no conclusive scientific evidence to support the existence of the phenomenon of menstrual synchronization in human beings.

So, while many women claim that period synchronization is a phenomenon that exists, this belief is, for the time being, categorized as a myth. Perhaps in the near future, scientific research will confirm this belief.