(HealthDay)—Exposure to ultrafine particles (UFPs; <0.1 μm) during the second trimester in utero is linked to the subsequent onset of asthma in children, according to a study published online Feb. 20 in the American Journal of Respiratory and Critical Care Medicine.

Eric Lavigne, Ph.D., from Health Canada in Ottawa, and colleagues examined the association between prenatal and early postnatal life exposure to UFPs (single-pollutant and multipollutant models accounting for coexposures to PM_2.5 and NO₂) and development of childhood asthma (up to age 6 years) among 160,641 singleton live births in the city of Toronto between April 1, 2006, and March 31, 2012.

The researchers found that 27,062 children had an incident asthma diagnosis during the follow-up period. Second-trimester exposure to UFPs (hazard ratio [HR] per interquartile [IQR] increase, 1.09) was associated with asthma incidence after adjustment for other factors. After additional adjustment for PM_2.5 and NO₂, UFP exposure during the second trimester of pregnancy remained positively associated with childhood asthma incidence (HR per IQR increase, 1.05).

"These findings highlight the need for further research on the effects of UFPs during the perinatal period on respiratory health in children," the authors write.

More information: Abstract/Full Text (subscription or payment may be required)

Journal information: American Journal of Respiratory and Critical Care Medicine