Infants born to women exposed to high levels of air pollution - PM2.5 constituents and several traffic-related pollutants such as carbon monoxide, nitrogen dioxide, sulfur dioxide - in the week before delivery, the day of delivery and the day prior to delivery are more likely to be admitted to a newborn intensive care unit (NICU), suggests a case-crossover analysis by researchers at the National Institutes of Health.

Data from the Consortium on Safe Labor, which compiled information on more than 223,000 births at 12 clinical sites in the US from 2002 to 2008 was analysed. Records from 27,189 singletons admitted into the NICU were linked to data modified from the Community Multiscale Air Quality Modeling System, which estimates environmental pollution concentrations in the US

Air quality data were matched in the area where each birth occurred to the week before delivery, the day before delivery and the day of delivery, which were then compared to air quality data two weeks before delivery and two weeks after delivery to identify risk of NICU admission associated with pollution levels.

• Exposure to high concentrations of organic compounds in the air was associated with a 147% increase in risk of NICU admission.
• Elemental carbon and ammonium ions presented similar increases in risk (38% and 39%, respectively), while exposure to nitrate compounds was associated with a 16% higher risk of NICU admission.
• Chances of NICU admission increased significantly with exposures to traffic-related pollutants on the day before and the day of delivery, compared to the week before delivery: 4% and 3%, respectively, for an approximately 300 ppm increase in carbon monoxide; 13% and 9% for an approximately 26 ppm increase in nitrogen dioxide; and 6% and 3% an approximately 3 ppm increase in sulfur dioxide.

Although the exact cause is not understood, researchers hypothesize that pollutants increase inflammation, leading to impaired blood vessel growth, particularly in the placenta, which supplies oxygen and nutrients to the developing fetus

These findings published online 12 July 2019 in the Annals of Epidemiology show that prenatal exposure to air pollution increases the risk for NICU admission and such newborns may require additional care during the hospital admission. Hence, pregnant women should avoid areas of high pollution and stay indoors and not venture out for walks when air pollution levels are high.

Dr KK Aggarwal

Padma Shri Awardee

President Elect Confederation of Medical Associations in Asia and Oceania   (CMAAO)

Group Editor-in-Chief IJCP Publications

President Heart Care Foundation of India

Past National President IMA