Carbon monoxide (CO) and nitric dioxide (NO 2 ) exposure during fetal life: impact on neonatal and placental weight, a prospective study.

Objective: This prospective study aims to analyze how CO and NO ₂ exposure during pregnancy affects birth and placental weight as well as umbilical arterial pH. Study design: The population in study includes 3614 women born in Italy, living in Lombardia Region, consecutively admitted to the Clinica Mangiagalli for an elective cesarean section from January 2004 to December 2006. Outdoor air quality data was provided by the Department of the Regional Environmental Protection Agency and obtained by a network of fixed monitoring stations distributed in eight geographical areas across the region. Results: A positive association was found between birth weight and the concentration of CO to whom women were exposed during the last 10 d of pregnancy (mean change g  + 28, 95% CI +1 to +55, p .04). Conversely, placental weight was not influenced by exposure to CO while a statistically significant weight reduction was related to an increase in NO ₂ exposure during the last trimester of pregnancy. Conclusion: Fetal weight was positively associated with an increased exposure to CO during the last 10 d of pregnancy. NO ₂ exposure was associated to a placental weight reduction. These findings underline the existence of a complex biological role of such pollutants, especially of CO, in cell oxygenation at a placental level.