**5.2 Air pollution**

During pregnancy, women have a unique immunological condition that causes modulation of the immune system at different stages of the pregnancy, which can lead to adverse reactions to environmental toxins and [51]. Also, pregnant women's ability to thermoregulate is compromised, making them particularly susceptible to heatwaves and air pollutants [52, 53].

Studies have shown links between prenatal exposure to environmental chemicals and adverse health outcomes that that cuts across life include impacts on fertility and pregnancy, neurodevelopment, and cancer. Warmer/higher temperatures can allow certain chemicals to break down into toxic elements, vaporize and easily enter the air we breathe, leading to adverse effects on fertility and pregnancy outcomes [11, 54, 55]. Climate change affects how chemicals deposited into the environment by factories, car emissions, and congestion in urban areas interacting with the air we breathe. Therefore, prenatal and early childhood exposure to air pollution, especially PM2.5, contributes to respiratory illness such as asthma, pneumonia and chronic obstructive pulmonary disease [56].

Because of the dangers these environmental exposures will have on maternal health outcomes, both the American College of Obstetricians and Gynecologists (ACOG) and the International Federation of Gynecology and Obstetrics (FIGO) have alerted the members of the reproductive and maternal health community about the far-reaching effects of climate change on maternal and neonatal health outcomes [57, 58].

As stated above, both increasing temperatures and air pollution are important factors impacting pregnancy and birth outcomes. Women who are exposed to hot temperatures/extreme heat, heat stress, or air pollution are more likely to have negative birth outcomes such as, but not limited to, miscarriages and stillbirth, preterm and low birth weight, and other preventable pregnancy and birth complications such as preeclampsia.
