Seasonality of fetal trisomy 21 - have ambient air pollutants played a role?

Objective: To examine the seasonality of fetal trisomy 21 and its relationship with ambient air pollutants. Methods: The averaged incidence by month-of-conception of the 113 cases (2002-2009) in our registry was correlated with month of conception and monthly ambient levels of nitrogen oxides (NOx, NO and NO₂), sulfur dioxide, carbon monoxide, and ozone as reported by the Hong Kong Environmental Protection Department at the month of, and four-week after, conception. Results: The incidence was highest in February (3.45/1000 births) and lowest in October (1.28/1000 births), and showed a significant difference ( p = 0.003) and positive correlation ( p = 0.003) from winter to autumn. It was also correlated with NO ( p = 0.017) and inversely with ozone ( p = 0.014) at conception. Conclusions: Seasonal variation in incidence of fetal trisomy 21 was correlated with ambient levels of nitric oxides and ozone. The role of environmental pollutants on fetal aneuploidy warrants further investigation. [ABSTRACT FROM AUTHOR]