Complications

• Complications can be from the metal buildup in the placenta - placental vascularization (Rani & Dhok, 2023)
• Air pollution causes low birth weight, early birth, and improper immune system development (Rani & Dhok, 2023)
• PM may reach the placenta and trigger oxi-inflammation (Chiarello et al., 2023)
• Pregnancy influences the epigenome and fetal programming (Chiarello et al., 2023)
  
  • Issues during embryonic development result in developmental adaptations and permanent changes in structure, metabolism, cardiovascular, physiological, and endocrine
  • Immature metabolism and the cellular proliferation period characterize the fetus and are highly vulnerable to pollutants exposure
• Elevated risk of adverse pregnancy outcomes associated with air pollution (Šrám et al., 2005)
• Air pollution and childhood mortality - significant correlation especially for infant respiratory mortality (Šrám et al., 2005)
• Air pollution and birth weight - SO2 and particles during late gestation contribute to low birth weight risk (Šrám et al., 2005)
• Air pollution and premature births - dust fall associated with neonatal deaths for premature births (Šrám et al., 2005)
• Air pollution from road traffic associated with low birth weight at term (Stock & Clemens, 2017)
• Small particle pollution exposure in pregnancy is connected to fetal growth, preterm birth, still birth, and respiratory morbidity in children - no causality (Stock & Clemens, 2017)
• Reduce risk by wearing facemask, but cannot reduce chronic exposures (Stock & Clemens, 2017)
  
  • Can change routes away from major roads and avoid being outdoors during poor air quality
  • Need policy change
• Pregnancy outcomes and outdoor air pollution (Stock & Clemens, 2017)
  
  • Linked to fetal development problems, pregnancy complications (including pregnancy-induced hypertensive disorders) and preterm birth (<37 weeks)
  • PM10 is associated with fetal overgrowth, preeclampsia - increases risk of abnormal fetal growth
  • Smaller PM particles are more harmful than the larger particles when it comes to adverse health effects  
    
    • PM2.5 can stay in atmosphere for 7-30 days - can lead to hypertensive disorders of pregnancy and maternal thyroid dysfunction
  • Pregnant women could inhale more polluted air than non-pregnant women due to maternal respiratory adaptations
  • Inhaling PM2.5 leads to increased risk of cardiovascular disease
  • Black carbon particles can end up in the placenta
    
    • What you breathe in goes from lungs to bloodstream and from the blood to the placenta since placenta acts as reservoir to decrease PAH transfer
• Pregnancy outcomes and indoor air pollution (Sarah J Stock, Tom Clemens, 2017)
  
  • According to the EPA, indoor air pollutants can be 2 or 5 times higher than outdoor air pollutants (indoor is buildings, vehicles, etc.)
• Lung development could be impaired, decreased function of lungs in infancy and childhood, more respiratory symptoms, more childhood asthma, and contributions to infant mortality (Korten et al., 2017)
• Environmental factors may permanently impact gene expression (Korten et al., 2017)
• Lung development and morphogenesis begins at 4-7 weeks and reaches the alveolar phase around 36 weeks (Korten et al., 2017)
  
  • Alveolarization continues through adolescence (Korten et al., 2017)
• Particulate matter and ozone exposure for the entirety of the pregnancy is significantly associated with preterm birth higher risks (Klepac et al., 2018)
• Air pollution and birth defects - limited evidence (Šrám et al., 2005)
• An increase to prenatal exposure to PM 2.5 was associated with reduced birth weight and gestational age Z scores in Rwanda and with reduced birth weight in Tanzania (Balakrishnan et al. 2023; Wylie et al. 2017)
• A 10 µg/m3 increase in PM2.5 resulted in a 0.069 standard deviation decrease in height-for-age and 9% higher odds of being stunted (Clarke et al. 2022)
• Approximately 10% of the preterm births in the world are attributable to PM2.5 exposure (Spahr, 2025)
• Emory study found links PM2.5 and the substances cortexolone and lysoPE(20:3) as potential triggers of early labor, as well as disruptions in protein digestion and absorption (Spahr, 2025)
• Long-term exposure to Traffic Related Air Pollution (TRAP) associated with low birth weights, smaller babies, and increased risk of preterm births (Fuller et al., 2023)
• Low birth weight, preterm birth, lower respiratory and other infections, diarrheal diseases, brain damage and inflammation, blood disorders, jaundice (State of Global Air | 2024)
• Miscarriage, stillbirths, congenital disorders and anomalies.  26% total newborn deaths linked to air pollution, 72% of which due to household air pollution from cooking (State of Global Air | 2024)
• Inverse relationship of gestational age and concentration of SO2 (Šrám et al., 2005)
• Air pollution and IUGR (birth weight below 10th percentile) (Radim J. Šrám et al., 2005)
  
  • Higher PM10 and PM2.5 levels significantly increased risk of giving birth to a child with IUGR (Šrám et al., 2005)
• Causal relationship between respiratory deaths and particulate air pollution in postneonatal stage (Šrám et al., 2005)
• NO2 exposure in the first two years of life is associated with lower attentional function, especially in boys (Crooijamans et al., 2024)
• Air pollution exposure during pregnancy and childhood linked to executive function impairment (Crooijamans et al., 2024)
• Wildfires linked to low birthweight and stillbirth, preterm birth risk increased by 3.4% (Gammon, 2024)
• Small increases in PM2.5 during pregnancy associated with increased risk of psychotic experiences and depression in children (Day, 2024)

Exposure

• Study conducted - exposure to organic carbon and particulate matter during egg and sperm development cycles are strongly associated with detrimental impacts on oocyte survival, fertilization, and embryo quality (Perkins, 2024)
• Healthy adult inhales 10-20 m^3 of air per day on average (Klepac et al., 2018)
  
  • Depends on body constitution and physical activity (Klepac et al., 2018)
  • Pregnant women breathe significantly higher oxygen and total volume (Klepac et al., 2018)
  • According to WHO, about 3 million premature deaths in 2012 worldwide may be due to AAP (Ambient air pollution) (Klepac et al., 2018)
  • Health of babies based on genetics, environment, and social factors (includes health of mother) (Klepac et al., 2018)
  • Significant association between particulate matter, ozone, and preterm birth (Klepac et al., 2018)
• In India, wives of traffic policemen had lower pregnancy success rates as air pollution is extremely high there (Perkins, 2024)
• Exposure to organic carbon during ovarian stimulation, the more likely that the eggs would not survive. (Perkins, 2024)
• “The pollutant also seemed to impact folliculogenesis and spermatogenesis, which are critical steps in egg and sperm development.” (Perkins, 2024)
• Outside is a risk due to fires and inside is a risk due to air filtration systems. Higher levels of ozone are associated with lower fertilization rates and high organic carbon rates on the day of oocyte thaw was associated with lower oocyte survival rates. (Perkins, 2024)

Impact on the Mother

• In the mother, metabolites and metabolic pathways are impacted by air pollution (Rani & Dhok, 2023)
• Exposure to air pollution may increase the health risks of the mother, such as pre-eclampsia (cardiovascular condition) (Royal College of Obstetricians & Gynaecologists, 2022)
• Exposure to air pollution increases risks for fertility issues and complications during pregnancy, such as stillbirth, miscarriage, and postpartum depression. It can decrease the success of IVF by over 30%. (Taylor, 2025)
• PM10 pollution linked to disruption of development of eggs, as IVF live birth rates are lowered by 38% due to PM10 (Devlin, 2024)
• Relationship between PAH exposure of mother before and during pregnancy linked to eczema incidence (Rauf & Pribadi, 2024)
• PM10 associated with increased miscarriage (Conforti et al., 2018)
• SO2, CO, NO2 may be linked to miscarriage and stillbirths (Conforti et al., 2018)
• Female infertility increased in recent years, affecting 1 out of 7 couples in developed countries (Conforti et al., 2018)

Calls to Action

• 20 fewer infant deaths per year could be achieved through The Pathway to Healthy Air in the UK created by The Clean Air Fund (Royal College of Obstetricians & Gynaecologists, 2022)
• To support women’s health and gender equality across the world, the RCOG is calling for the UK Government to deliver their manifesto commitment of reversing cuts to the overseas aid budget, ensure strong international commitments to support lower-income countries, and be a strong advocate for gender equality (RCOG, 2025)