There are many factors that can have an impact on female fertility, from nutrition, weight and physical health to psychological stress and use of medications.
One key influencer that women increasingly need to take into account is the environment in which they live. Environmental factors have been strongly linked to women's ability to conceive and have a healthy pregnancy.
Air pollution is posing a growing threat to health all over the world. According to a World Health Organisation (WHO) report, more than nine out of ten of the world's population (92%) live in places where air pollution exceeds safe limits.
There is a strong link between this health risk and fertility. Research has shown air pollution is associated with a diverse set of outcomes, from altered production of sperm and eggs to epigenetic changes and birth defects.
A study involving mice conducted by the Federation of American Societies for Experimental Biology highlighted how breathing high levels of the ozone pollutant at ground level could affect women's ability to conceive. The findings showed that breathing ozone on the day of ovulation decreased progesterone levels in female mice and also reduced the number of ovulated eggs.
Dr Carla Caruso, a resident physician at the Pennsylvania State University College of Medicine comments:
"In addition, this acute exposure to ozone affected important brain and ovarian signaling events that are key for the ovulation process"
Globally, air pollutants can be two to five times higher indoors than outdoors. This can also be a particular threat in low and middle income countries where around 3 billion people still cook using solid fuels (such as wood, crop wastes, charcoal, coal and dung) and kerosene in open fires and inefficient stoves, creating an environmental risk that could have a significant impact on fertility and health during pregnancy.
Exposure to chemicals
Exposure to potentially harmful chemicals is another increasingly common health concern in the modern world, particularly for women who are trying to conceive or are currently pregnant.
Organic pollutants and endocrine-disrupting chemicals (EDCs) in the environment have an effect on both male and female fertility.
EDCs are typically man-made and are found in materials such as pesticides, metals, food additives and personal care products. Human exposure commonly occurs via the ingestion of food, dust and water, the inhalation of gases and particles in the air, and through the skin.
As well as altering the reproductive function in both men and women, EDCs can be transferred from mothers to children across the placenta and through breast milk.
Given the range of external factors that impact female fertility and general health, as well as the development and well-being of babies and children, it has never been more important for women to be aware of the environment in which they live. Chemical exposures are in the food we eat, the water we drink and the air we breathe. They are found in the personal products of our daily lives. Recommendations include rinsing all produce in water, consuming pesticide-free products, avoid heating in plastic in microwaves, reviewing personal care products for EDCs like phthalates, and avoiding cooking in teflon pans.
Environmental Working Group offers great advice on all products to avoid.
Globally, minimising environmental threats to human health and reproduction is a necessity if we are to progress towards the 2030 Agenda for Sustainable Development (SDGs), this places an onus on governments and authorities to guarantee ongoing action to protect public health and manage environmental risks.
Although political, economic, and social challenges remain, it is hoped that all stakeholders will continue to collaborate and move the agenda forward, because there is much at stake for reproductive health and fertility for this and future generations.
This piece has received input from:
Dr Linda Giudice and Dr Jeanne Conroy, Chairs of FIGO's Working Group on Reproductive and Developmental Environmental Health