Air pollution during pregnancy poses severe documented risks to fetal development, with harmful pollutants crossing the placenta and directly interfering with critical growth stages while triggering maternal inflammation and oxidative stress. Research demonstrates strong associations between prenatal exposure to specific PM2.5 components — particularly sulfate and ammonium — and increased autism risk, with the second and third trimesters representing especially vulnerable windows. These pollutants disrupt normal fetal brain development and raise risks for premature birth, low birth weight and long-term neurological consequences.