Carbon monoxide (CO) is directly released from motor vehicles engines, which are a major source of this pollutant in the LA Basin [1] 5. CO inhaled by pregnant women may threaten the unborn child's growth and mental development. Because CO competes with Oxygen to achieve dispersion throughout the blood stream, fetal hypoxia (lack of oxygen) may result at high levels of maternal CO exposure, however the exact amount of exposure of CO to become a fetal threat is unknown [6] High levels of carbon monoxide are also found in cigarettes, it is advised that pregnant women avoid smoking so as to not run the risk of affecting their child's growth or mental development.