Pregnancy

Sex and Gender-based Analysis of this topic

Definition
Through the air, water, food, drinks, cosmetics, personal care products, everyday household items, and products used in the workplace (see Occupational Health and Safety), our bodies are perpetually coming into contact (digestion, lungs, skin, placenta) with chemicals [1]. The growing concern is based on the ubiquitous nature of these chemicals and combinations of chemicals (a significant challenge for accuracy in research), the understudied potential for their synergistic action, their known ability to act at low doses (in everyday environmental exposure) and their ability to mimic important signalling mechanisms in body systems, such as endocrine disrupting chemicals (see Endocrine Disruption) [1-4]. Fully developed human bodies do have the resilient capacity to counter some of the damage caused by a detectable chemical exposure, by adapting to and repairing the damage inflicted on genes, proteins and cells [1]. However, bodies are at their most vulnerable to the actions of chemical exposure when they are going through rapid periods of development (known as windows of vulnerability or sensitivity), such as in the womb, during infancy, in early childhood, in puberty and during pregnancy [1, 2, 5, 6]. 
 
 
Sex Issues
Diethylstilbestrol (DES; medication used to prevent miscarriages) is a prime example of how prenatal exposure caused significant reproductive health repercussions in daughters, and to a lesser extent, sons, resulting in lasting, multigenerational issues and permanent genetic changes [1, 2, 5, 45.] 

Air pollution is correlated with higher rates of preterm birth, low birth weight and neural tube defects [2, 11-13]. Some known toxic air-bound compounds are SO2, CO, nitrogen oxides, O3, particulate matter and polycyclic aromatic hydrocarbons.  
Pesticides, such as DDT, DDE, Hexachlorobenzene, Tributyltin are associated with foetal growth restriction, congenital anomalies, neural tube defects, neuro-toxicity, neuro-degeneration later in life, endocrine disrupting effects (both oestrogens and androgens), childhood obesity, obesity later in life, increased rates of cancer, and impaired sex-ratios (more females) [2, 16-24]. Along with pesticides, many other contaminants are found in drinking water [hyperlink to drinking water quality] and more chemicals are formed as the by-products of water disinfection [2, 25, 26]. 

Phthalates, found in many consumer-available products, demonstrate endocrine disrupting potential, which is linked to rates of low birth weight and preterm births, a decreased ano-genital distance in male infants and children, and increased problems in mental and psychomotor development [2, 28-37]. Bisphenol-A (BPA) is another important compound found ubiquitously which is known to cause chromosomal abnormalities, miscarriages, male offspring reproductive dysfunction and is suspected to be a factor in the obesity epidemic [2, 20, 38-42]. Other compounds found in household products: polychlorinated bisphenyls (PCBs) and flame-retardants (such as Polybrominated diphenyl ether) have been linked to poorer neuro-developmental outcomes in children and fertility issues in women [2, 7, 43].
 
 
Gender Issues
Aspects of our environment, such as nutrition, exercise, stress and health status affect the body’s ability to compensate for the challenges caused by chemical exposure [1, 2]. Social economic factors are important for birth outcomes and in combination with the disparity of environmental exposure cause an undue burden to those living in poverty, a population overrepresented by women[2, 23]. Conversely, higher socioeconomic status may act as a protective factor against the effects of environmental exposure, particularly air pollution[2]. Risk factors for prenatal exposure to alcohol are higher maternal age and lower education level, prenatal exposure to cocaine and smoking, custody changes, lower socioeconomic status and paternal drinking and drug use at the time of pregnancy, and reduced access to perinatal care and services, inadequate nutrition and a poor developmental environment [47]. These risk factors may also weaken resiliency to other environmental exposures.

Certain occupational exposures are key for pregnant women, especially working with organic solvents, such as in dry cleaning, and printing, or working with particular toxic consumer products such as cleaning products and nail polish removers[2]. Principally, exposure to pesticides and similar products by pregnant women working in agriculture or living near or downstream from a farm can cause defects of the central nervous system and malformations in offspring[2, 23]. Pesticide exposure also threatens overcrowded inner city dwellers who make use of pesticides indoors for insect control [2, 23].

Further, it is important to consider the negative impacts of adverse birth outcomes on financial and emotional stability of families, including the caregiver burden felt more strongly by women [2]. 
 
 
Diversity
The geographical location of polluting industries near marginalized communities poses a significant threat to human health. Maternal exposure to air pollution is known to differ by race [2]. Marginalized communities face a double burden of socioeconomic inequity and environmental exposure (both residential and occupational) leading to significant adverse health outcomes [2].
 
 
Critique
Much of the research that does exist in the area of environmental exposure and pregnancy overwhelmingly focuses on foetal outcomes rather than considerations for maternal outcomes, an area requiring further research. Despite some progress, there exists a wealth of chemicals readily available in consumer products and in the environment that to be researched, especially for the synergistic effect of combinations (the “cocktail effect”) and products of combined chemicals[1, 2, 49]. Historically, we have also learned that the effects of chemical exposure are not always immediate, as in DES, and may cause lasting or latent, multigenerational effects, suggesting the importance of continued monitoring of cohorts of exposed children and grandchildren [1, 2, 5]. As our knowledge of basic human biology and methods of measurement of reproductive health and chemical exposure expand (through both animal and human studies), more can be studied regarding potential areas of action of chemicals as well as inform prevention of exposure. Research in racial and ethnic inequities in chemical exposure and reproductive health, both in risks and protective factors, are desperately lacking.  

Currently, the government of Canada is undertaking a program known as the Chemicals Management Plan which could greatly benefit from sex and gender-based perspectives[50]. 
 
 
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health status > reproductive health & the environment > pregnancy