Climate Change and Its Impact on Female Reproductive Health

1. Introduction

Climate change is influencing human lives and health in numerous ways. An area’s temperature and climate are influenced by the amount and angle of sunshine it receives, which is determined by its distance from the equator where lower temperatures at higher elevations are observed because of the thinning of the atmosphere and the drop in air pressure. Mountains and valleys are examples of physical land features that can affect the climate through modifying patterns of precipitation and wind. Human actions, particularly the burning of fossil fuels and deforestation, contribute to climate change and global warming by releasing greenhouse gases into the atmosphere. It threatens the essential components of good health – clean air, safe drinking water, a nutritious food supply, and safe shelter – and has the potential to undermine decades of progress in global health [1]. Human health in general is significantly impacted by climate change, which affects both mental and physical health with a number of societal, environmental, and health-related issues impacted by climate change, and women being the front-runners by being disproportionately affected. Between 2030 and 2050, climate change is expected to cause approximately 250,000 additional deaths per year from malnutrition, malaria, diarrhea, and heat stress alone. The direct damage costs to health are estimated to be between 2–4 billion US dollars per year by 2030 [1].

The relationship between female health and climate change is a complicated, multidimensional problem with broad ramifications. Women are more vulnerable to the effects of climate change than men – primarily as they constitute most of the world’s poor and are more dependent for their livelihood on natural resources that are threatened by climate change. Women often have a strong body of knowledge and expertise that can be used in climate change mitigation, disaster reduction, and adaptation strategies. Furthermore, women’s responsibilities in households and communities, as stewards of natural and household resources, position them well to contribute to livelihood strategies adapted to changing environmental realities [2]. Infertility is a major problem in modern society and recurs in as much as 17.5 % of the estimated lifetime prevalence of infertility in 2022 [3]. The American Society of Reproductive Medicine (ASRM) delineates infertility as failing to conceive after one or more years of attempts at natural fertilization, with the World Health Organization (WHO) reporting that up to 80 million women worldwide have been affected by this disease to date, with a prevalence of ~50 % of all women in developing countries [4].

India is a populous country with the population of 1.42 billion people and overall a developing country with the largest size of population in the world. In the recent years, India has crossed the border with China and became the most populous country with a healthy reproductive population. Even though India is a highest population country, the fertility rates in India have dropped from 5.622 to 2.12 in the past six decades. There are various reasons for the reduced fertility like poverty social initiatives but increased temperature and climate change have also contributed to reducing fertility rates recently [5]. The average annual temperatures in India are projected to be increasing between 1.7 and 2.2 °C by 2030, with an increase in the intensity and duration of heat waves all along the Indian subcontinent [6]. The number of deaths has already increased due to high temperature over the past 15 years, and as reported by various researchers [7–9]. Various studies have reported on heat-related health effects in women especially in aged and pregnant women [10–12]. Women have higher metabolic rates; the occurrence of thicker subcutaneous fat reduces their radiative cooling and dissipates less heat by sweating [13]. Other factors, like poor access to healthcare and reduced cooling facilities due to safety with culturally prescribed heavy garments, reduce evaporative cooling and, there is a lack of awareness among women about heat vulnerabilities.

2. Consequences of Climate Changes

Numerous approaches exist for environmental influences to impact female fertility health patterns where it can be affected by a variety of exposures, lifestyle decisions, and environmental factors with a wide range of direct and indirect consequences, which will be the subject of a broad discussion in this review.

2.1 Heat Stress

Heat waves are becoming more common and intense because of rising global temperatures. The scale and nature of the health impacts of heat depend on the timing, intensity and duration of a temperature event, the level of acclimatization, and the adaptability of the local population, infrastructure and institutions to the prevailing climate [1]. Mammals, including humans and livestock animals, are living in such a modifiable environmental condition. Most mammals have body temperatures of 35–39 °C [14]. These temperatures are maintained above environmental temperatures through the generation of metabolic heat. Body temperatures are normally maintained in a narrow range by heat production and loss, although disease, poor nutrition, and extreme environmental temperatures can upset the balance [15]. Inconsistent menstruation and polycystic ovarian syndrome (PCOS) are two other disorders that are known to be exacerbated by heat stress, thereby influencing female regular ovulation cycle. Young girls who are having irregular periods for a longer time are at greater risk of developing gynecological problems resulting in an increased risk of PCOS and other reproductive diseases [16]. Extended exposure to high temperatures can cause menstrual cycle disruption and hormone imbalance, which can have a detrimental impact on the reproductive health of women. Exposure to higher temperatures was found to be associated with a lower ovarian reserve. The results from an association study comprising 631 study subjects attending the Massachusetts General Hospital Fertility Center (2005–2015) who participated in the Environment and Reproductive Health Study, between ambient temperature and antral follicle count (AFC), a standard measure of ovarian reserve has raised a concern that rising ambient temperatures worldwide may result in accelerated reproductive aging among women [17][18]. Heat stress can affect ovarian follicle growth in females, which is important for healthy ovulation and conception. Issues with fertility may arise from modifications in follicular development. A pre-clinical chronic heat-stress study comprising 48 female mice after exposure to a constant temperature of 25 °C for 7, 14, 21 or 28 d (n = 6) or to 42 °C for 3 h per d for 7, 14, 21 or 28 d (n = 6), has shown a decrease in serum estradiol and aromatase in antral follicles but increased number of atretic follicles and granulose cells undergoing apoptosis, which may explain the decreased fertility commonly observed in heat-stressed animals [19]. As reported, the secondary sex ratio at birth (male/female) may also be affected by changes in environmental temperatures [20][21].

2.2 Food Security

Access to adequate, safe, and nutritious food is a prerequisite for food security, which is essential for overall well-being, including reproductive health. Climate change is likely to worsen the food security situation through its impact on food production, which may indirectly affect fertility behavior [22]. Reproductive health can be promoted by eating a diet that is well-balanced and rich in necessary nutrients but with a change in climatic trends and the effect it may have on food security and agricultural output is not to be overlooked. Climate change may have an impact on food production and availability, which could alter food prices and accessibility. Climate shocks create a strain on food production, transportation infrastructure, and access to food for much of the vulnerable population [23]. Changes in agricultural practices brought on by climate change affect the nutritional content of food, which may affect fertility and reproductive health. Malnutrition and food shortages can directly affect the reproductive health of women, influencing both mother and child health and fertility. Deficient food intake, inadequate alimentary regimes, strong dietary restrictions, and a general lack of nutrients result in loss of both body weight and physical performance, delayed puberty, lengthening of the postpartum interval to conception, lower gonadotropin secretion levels with alterations of the physiological ovarian cyclicity, and increased infertility. Poor intake of proteins, micro- and macro-minerals, and vitamins is associated with a reduction in reproductive performance since the altered energy balance correlates with the reduced ovulatory maturation in women [24]. Thus, inadequate nutrition is closely linked to female reproductive pathophysiology. This is confirmed by the fact that both bulimia nervosa and anorexia, namely two pathologic conditions affecting 5 % of women of childbearing age, are indisputable causes of amenorrhea, infertility, and miscarriages [25]. In females, reproduction involves much greater energy expenditures than for males and as a protective mechanism against under nutrition, ovarian activity is suppressed in women with eating disorders and exercise-induced amenorrhea through pathways in the hindbrain. The combined prevalence of Bulimia nervosa and Anorexia nervosa is approximately 5 % among women of reproductive age. Both disorders suppress ovulation in severely affected women and account for up to 60 % of women with an ovulatory infertility [26].

2.3 Water Scarcity

The interdependence of water, agriculture, economics, and health highlights the significance of tackling water scarcity as a component of larger initiatives to advance sustainable development and enhance quality of life. Water scarcity can have complex effects on reproduction that damage both human well-being and agricultural output (Table 1). Unsafe water can also interfere with people’s reproductive health, for example, by increasing the chances of experiencing infertility or jeopardizing a person’s ability to have a healthy pregnancy [27]. Droughts have direct physiological effects on organisms, such as an increased risk of lethal dehydration that can cause mass mortality events and rapid population declines in birds, mammals, and amphibians with potential impacts on trophic networks and communities [28]. Reproductive tract infections and pregnancy difficulties can be made more likely by not having access to clean water and sanitary facilities.

2.4 Psychosocial Stress

Climate change brings exposures to heat, air pollution, poor quality food, and infectious diseases that have significant direct effects on women and their mental health. These environmental impacts are multifaceted in their consequences and raise risks of depression, suicide, violent victimization, post-traumatic stress disorder, and various other neuropsychiatric symptoms [29]. Extreme weather, temperature increases, sea level rise, and environmental degradation are just a few of the repercussions of climate change that can have a significant negative impact on people's mental health and general well-being. It is becoming more widely acknowledged that psychosocial stress is significantly influenced by climate change, which has an impact on both individuals and societies on multiple levels. Periodic stress has been connected to irregular menstruation and problems with fertility. Stressful stimuli cause the activation of the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic-adrenal-medullary (SAM) axis [30]. The hormones secreted by these systems after stressful stimuli result in an abnormal, prolonged and/or excessive stress-induced body’s set-up that can potentially produce long-term neuroendocrine changes, affecting female fertility [31]. All stress-induced hormones from the adrenal cortex and medulla are responsible for several physiological and mental consequences, which cause the individual to fight with or flight from the stressor. Differences in individual responses could be explained by findings from ewes showing that animals with divergent cortisol responses to ACTH exhibit functional differences in the HPA axis due to innate differences in the gene expression/function of HPA molecules [32]. Further results from female Cynomolgus monkeys, exposed to mild combined psychosocial and metabolic stress, show a selected and specific (rather than generalized) increased activity in the adrenal framework significantly related to stress-induced reproductive dysfunction [33].

2.5 Emerging Pollutants

Environmental pollution, which exerts potentially harmful effects on earth and atmospheric ecosystems, is caused by the presence of chemical, biological, and physical substances deemed pollutants [34][35]. Pollutants can originate from a variety of sources, such as the air, water, food, and workplace environments. Pollutant persistence and distribution can be impacted by climate change. Hormone regulation may be disrupted by exposure to certain pollutants, such as endocrine-disrupting chemicals, which can affect reproductive health. The most common direct or indirect causes of female infertility are advanced age, endocrine problems and damage to the reproductive apparatus (vaginal, cervical, uterine, tubal, and pelvic-peritoneal diseases). Premature ovarian insufficiency (POI), endometriosis and polycystic ovarian syndrome (PCOS) or sexually transmitted diseases have widely recognized roles in fertility failure, although approximately 15–30 % of cases remain unexplained [36][37].

3. Conclusion

The climate of the Earth has naturally fluctuated over geological time spans. However, over the past few decades, human activity has significantly changed the climate, leading to both climate change and global warming. This has led to rising sea levels, altered ecosystems, and an increase in the frequency and intensity of extreme weather events. Part of the effort to tackle climate change includes the implementation of international agreements such as the Paris Agreement, which aims to reduce greenhouse gas emissions and limit rises in global temperature. While adaptation techniques work to assist populations in adjusting to the effects of climate change, mitigation measures concentrate on lowering emissions. Global efforts to combat climate change must also prioritize the development of renewable energy technologies, sustainable behaviors, and public awareness. A comprehensive and inclusive strategy that takes into account the particular vulnerabilities and roles that women play in many civilizations is needed to address the nexus of female health and climate change. Faced with climate change, advocacy, education, and legislative actions can help to increase women's resilience and reduced the negative effects on their health. It is critical to recognize that these relationships are complex and that a range of variables, including geography, socioeconomic status, and underlying medical issues, may have an impact. Furthermore, research on the effects of climate change on the health of female reproductive systems is still underway, and as scientists look further into these intricate relationships, new knowledge may become available. Mitigation techniques and climate change adaptation may be essential for maintaining environmental sustainability and human health, especially reproductive health. A comprehensive strategy that incorporates gender-sensitive legislation, community resilience-building, and climate change mitigation techniques is needed to address the psychosocial effects of climate change on women. Understanding the intersectionality of vulnerabilities and addressing the particular difficulties experiencedby women in various situations are crucial. It is important to remember that different factors, including exposure type and level, individual sensitivity, and exposure duration, might have different effects on female fertility for chemical contaminants. Furthermore, this field is still being researched, and fresh discoveries could shed more light on the connection between particular contaminants and female fertility. People can take steps including limiting exposure to known dangerous chemicals, maintaining a healthy lifestyle, and staying knowledgeable about environmental factors that may affect reproductive health to avoid the dangers linked with chemical pollution and female fertility. Seeking counsel and help from healthcare professionals or reproductive specialists can be beneficial if issues emerge. A comprehensive strategy that takes into account sustainable farming methods, healthcare access, economic empowerment, and nutritional education is needed to address the complex interactions between female reproduction and food security. Communities' general growth and well-being can benefit from policies and initiatives that work to enhance both food security and reproductive health. One should keep in mind that this field is complex and constantly changing, and our understanding of these relationships is always expanding.

Acknowledgement: The authors would like to thank JSS Academy of Higher Education & Research, Mysuru for their constant support for the research.