Analyses that took the EU limit value of 50 μg/m 3 as a cutoff point revealed a nonsignificant OR for the whole group but a highly significant result for late neonatal mortality, with an OR for dying on days with PM 10 > 50 μg/m 3 of 1.74 (95% CI, 1.18–2.58; p = 0.006), compared with days below the cutoff value ( Table 2 ).
In all settings, subanalyses of congenital malformations of the circulatory or respiratory system (ICD-10 codes Q20–Q28 and Q30–Q34, respectively) revealed similar ORs as in the whole group of congenital and chromosomal abnormalities (Q00–Q99), but because of a smaller sample size, these results did not reach statistical significance.
When we stratified the analysis with the EU limit value by cause of death, the highest OR (for congenital and chromosomal abnormalities) just missed significance.