Did you know that ladies all over the world have different cycle patterns? This may be due to different climate zones.  

Let’s talk about the science behind it first. 

Your cycle is influenced by the key hormones estrogen and progesterone, so what does your country of residence have to do with it? The answer is sunshine. Yes, sunshine affects your cycle by increasing  the production of vitamin D in your body and suppressing melanin production. This makes your body produce more estrogen, which leads to more frequent ovulation and consequently shorter and more frequent menstrual cycles. 

Latin American women may have shorter cycles

Women who live in tropical and subtropical climates (like in Latin America, Spain, Italy, and southern states of the U.S.) tend to have shorter cycles and, more frequent menstruation. This happens because the more ultraviolet rays there are in the area, the more vitamin D is produced in your skin, and the more often ovulation tends to occur.  

In summer, women’s cycles may also become shorter and you may appear to menstruate a little more often than in winter. This also happens due to the amounts of ultraviolet rays. 

Women living in Northern Canada, Finland, and Norway may ovulate less and have longer menstrual cycles. 

According to studies, ovarian activity is greater in summer than in winter due to the prevalence of sunshine. Sunshine helps the body increase its secretion of ‘Follicle Stimulating Hormone’ (FHS), a hormone that helps to regulate the reproductive processes of the body.

In winter, women may ovulate less frequently and experience a longer menstrual cycle compared to summer. 

As cold can provoke menstrual cramps, women living in northern countries usually tend to have more cramping than those living in the south. 

In addition, the cold may also constrict blood vessels, which can alter menstrual blood flow and increase menstrual pain.

Women in larger cities like Hong Kong, Los Angeles, etc., may have irregular cycles. 

Research has shown that levels of the stress hormones cortisol, cortisone, epinephrine, and norepinephrine increase with dirtier air. So do the levels of blood sugar, amino acids, fatty acids, and lipids. All of them affect the menstrual cycle in women. A higher content of these hormones may lead to more irregularity of the menstrual cycle (if there is no other health-related reason for this). Thus women who live in large industrial or busy cities are more likely to have irregular cycles. 

Your place of residence is not the only factor that affects your cycle. Our bodies are quite sensitive to what we eat, how much we weigh, and how much stress we are exposed to.