Heatwaves and hormones: How climate change is taking a toll on women’s menstruation cycles

Research shows menstruation is either delayed or occurs much earlier than expected in countries most vulnerable to climate change.
Published July 3, 2024

My sister got her first period at the tender age of seven and a half. Not prepared for the pain that comes with menstruation, the mental and physical exhaustion took the best of her. A year later, her period mysteriously stopped and never occurred again until the age of 12.

Menarche, the first menstrual period in a female adolescent, usually occurs between ages 10 and 16, with an average onset of 12.4 years. It often happens unexpectedly and is typically painless. However, the National Institute of Health (NIH) has recently found that menstruation is either delayed or occurs much earlier than expected in countries most vulnerable to climate change.

Pakistan is among the top-ranking countries that are bearing the brunt of this global crisis. Over the past 50 years, the country’s annual mean temperature has risen by about 0.5°C, with the number of heatwaves increasing nearly five-fold.

In May 2022, when temperatures across the country broke a 60-year record, 16-year-old Fariha Atiq — who started menstruating at the age of nine — witnessed possibly the worst period of her life.

“I was completely unequipped to deal with my period. Somehow I coped with it, but as time passed, the seasonal changes worsened my cramps. I remember in the summer of 2022, from April to August I couldn’t move my legs during my menstrual cycle,” she told Dawn.com.

Fariha’s mother, Mrs Atiq, took her to various gynaecologists but all of them described what the teenager was experiencing as ‘normal’, which was far from the pain she endured. Mild to moderate pain before and during menstruation is typical, but severe cramps can stem from various factors.

Mrs Atiq continued her search for a gynaecologist who could ascertain the reason for her daughter’s pain. Eventually, she found Dr Junaid Ansari, an obstetrics expert at Abbasi Shaheed Hospital, Karachi. He explained that the pain was caused by elevated levels of cortisol — a stress hormone influenced by temperature.

Cortisol increases with rising temperatures, contributing to dysmenorrhea, which nearly immobilised the teenager two years back.

Link between hormones and rising temperatures

For most women, menstruation is typically ‘painless’; some, however, experience severe cramps. This is a symptom of dysmenorrhea — pain during the menstrual cycle — and occurs due to the release of cortisol.

Cortisol is a hormone that is released during stressful situations and plays several roles in the female anatomy. It regulates blood sugar levels, metabolism, and blood pressure, and acts as an anti-inflammatory agent. Moreover, the hormone influences the menstrual cycle and prepares the body for pregnancy.

“The primary cause of a prolonged or delayed period can be the release of cortisol, which changes from season to season. For example, in winter, the release is higher, which disrupts the cycle,” Dr Ansari explained to Dawn.com.

The doctor highlighted, however, that he had observed the hormone peak during summers due to intense heat. “Very recently, I came across a 12-year-old girl with a decent body mass index, who wasn’t able to move due to extreme cramps, that too during May and July,” he shared.

“After recommending a cortisol blood test, we discovered that her cortisol level was 30 mcg/dL, significantly above the normal range of 14-20 mcg/dL for someone her age. We opted to monitor the levels and were surprised to find them returning to normal by the end of August following rainfall.

“While I continue my research, I am convinced that severe climate change is causing disruptions in menstrual cycles,” Dr Ansari added.

Extreme stress can disrupt the working of glands that control hormones such as cortisol and are responsible for the release of oestrogen needed for female reproductive characteristics.

Researchers at Poznan University of Medical Sciences in Poland have identified seasonal patterns in cortisol levels among female medical students. The study involved testing students twice in winter and twice in summer, with saliva samples collected every two hours over 24-hour periods to measure cortisol and inflammation markers.

Participants also completed lifestyle questionnaires detailing their sleep habits, diet, and physical activity levels. Unlike previous studies conducted in varied home environments, this research found higher cortisol levels during the summer sessions, while inflammation levels remained consistent across seasons. This further strengthens the argument that rising temperature has an impact on menstrual cycles.

(Un)common conditions

Contrary to popular opinion, dysmenorrhea is not a common condition.

“Most girls who come to me with cases of severe cramps are told by gynaecologists that cramps are normal, which is not true,” Dr Asifa Sofia of the Abbasi Shaheed Hospital told Dawn.com.

“This condition has developed in the last five years, and most patients I attend, the girls go through a painful period through winter,” she said.

Primary dysmenorrhea, the doctor explained, causes pain before and during menstruation. On the other hand, periods that become painful in the later stages could indicate secondary dysmenorrhea, which is often linked to conditions such as endometriosis or uterine fibroids that affect the uterus or pelvic organs.

“This usually occurs due to hormonal changes,” she highlighted, adding that painful periods and disruptions in blood flow were directly connected to erratic weather patterns in the region.

“I work with women from both urban and rural areas. One thing I have observed, which is a common pattern, is that with fluctuating temperatures, the sizes of follicles are affected, which in turn impacts the oestrogen levels,” Dr Sofia said.

The follicle is a small, fluid-filled sac in the ovary that contains one immature egg. Disruptions in size can alter hormones that regulate puberty, menstrual cycle, pregnancy, bone strength and other functions of the female body.

Sabiha, one of Dr Sofia’s patients from Thar, is being treated for an irregular period cycle. In May 2021, she started experiencing severe abdominal pain during menstruation. Like several other women, the 24-year-old initially brushed off the pain until one day, while working around the house, she fainted.

In Thar, May and June mark the hottest months of the year with temperatures reaching up to 122°F (50 °C).

“After that fall, my period has never been normal. I either bleed for 12 days straight or I don’t bleed at all. Irrespective of that, the pain stays the same,” she said. When asked if she had experienced such cramps before she began menstruating, Sabiha replied in the negative.

Sabiha is one such case. Dr Sofia told Dawn.com that she had treated patients after the 2022 floods whose period cycles took a hit from the massive disaster. “Today, even the slightest change in temperatures either alters their follicle size or their oestrogen levels which is alarming,” she pointed out.

Migration and displacement

“My period had always been regular until floods hit my town … suddenly, I started bleeding on random days,” Geetanjali, a resident of Balochistan’s Nasirabad district, recounted.

“I would not get periods for months, and then suddenly I would start bleeding out of nowhere,” said the 25-year-old. “Some days, the bleeding would be so bad and at other times it would just be a drop.”

These disruptions have taken a toll on Geetanjali’s physical health; she has lost 25 kilogrammes in the last three months.

Climate change triggers natural disasters, leading to mass migration which contributes to disturbance in the menstrual cycle. When Pakistan was hit by gigantic floods two years back, women went through brutal menstruation woes, the traces of which can be seen and felt even today.

Alongside poor menstrual hygiene, the affectees were also exposed to pollutants that affected the uterus. As per a systematic review published in the International Journal of Environmental Research and Public Health, pollutants affect the timing of menarche differently depending on the chemicals involved.

Studies have connected exposure to lead, polychlorinated biphenyls (PCBs), and flame retardants with delayed periods. Conversely, some toxicants such as endocrine-disrupting chemicals and the herbicide atrazine have been linked to early menarche.

PCBs were found in floodwaters heavily polluted with human and animal waste, impacting not only the onset of periods but also the shedding of the uterine lining, resulting in irregular menstrual cycles.

According to Geetanjali’s attending doctor Tahira Kashaf, the 25-year-old’s menstrual cycle had a lot to do with her sudden displacement and the stress that came with it.

“Her follicular size was affected by a high cortisol release and low oestrogen levels, leaving her body struggling with the heavy blood flow and cramps,” She said. “I’m concerned she might develop anaemia in a few days.”

The doctor added that a majority of female patients she had treated following the floods, particularly from Sindh and Balochistan, faced a similar problem.

“During a fertility cycle, when a follicle measures between 18 and 22 millimetres in diameter, it indicates rising oestrogen levels and thickening of the uterine lining. However, in the women who I treated post floods, the follicular size ranged between 9-12 millimetres, which indicated that oestrogen levels are extremely low,” Kashaf added.

Erratic patterns

In the past five years, Pakistan has experienced both intense heat and cold. Irregular periods aren’t limited to summer when temperatures rise rapidly, but can also occur in winters.

“I experienced intense cramps last year which made me scream, especially from the end of December to the middle of January,” said Arwa, 22. “I clocked my cycle and consulted a doctor, who asked me to get my melatonin checked.

“When I took the test towards the end of January, it was very low,” she recalled. Surprisingly, Arwa’s pain vanished by February, with regular menstruation cycles until April. But the pain returned in May, much more intense this time.

Aniqa Sajid, a mother of two, narrated going through a similar ordeal on the first and second days of her period.

“This is new to me because it has been happening for the last two years and it only happens during winters. Initially, it was just pain and I was able to move around, but with time … within six months it got so bad that even a couple of painkillers couldn’t help,” she said.

According to the NIH, the absence of natural sunlight during winter can disrupt serotonin and melatonin levels — which also play a part in regulating the menstrual cycle — in the body. This hormonal imbalance can lead to heavy periods. Additionally, when the temperatures decrease, blood vessels compress, leaving a narrower pathway for blood flow and contributing to heavier menstruation.

Dr Tahira Masood, a gynaecologist at the Liaquat National Hospital, also told Dawn.com that menstrual cramps can be intensified during winter.

“Dysmenorrhea is often caused by the secretion of hormone-like substances called prostaglandins. Cold weather can trigger an increase in these substances, leading to more painful cramps.

“The constriction of blood vessels in cold weather can exacerbate menstrual cramps. Many women report more severe cramps during winter, indicating that this is a common experience,” she explained.

Until a few years ago, menstruation was a taboo topic, hardly ever discussed in public. While this has improved over time, especially in urban areas, conversations on period pain and women’s health are still minimal.

As Pakistan scrambles to tackle the climate crisis, it is important to understand that this cannot be done without addressing gender equity, especially the underlying barriers that cause women to be disproportionately affected by natural disasters.

“Most women I come across have no clue that the changes they have been enduring in their menstrual cycles occur because of climate change,” Dr Tahira said, stressing the need for awareness.

She added that women’s health could not be compromised and in the long run, sustainable changes such as temperature-dependent tampons, hormonal medicines and other natural resources that keep the body running need to be normalised.