Table 2.

Adjusted associations between the exposome and fetal growth (ExWAS approach)

Exposure variable	Exposure family	Transformation	IQR	ICC	ExWAS
					Estimate (95% CI)a	P-value
Lead	Metals and essential elements	Log2	0.5	0.73	−48.6 (−90.5; −6.7)	0.023
PM2.5 absorbance, 3rd trimester of pregnancy	Atmospheric pollutants	Ln	0.4	b	−49.9 (−94.4; −5.5)	0.028
PM2.5 mass concentration, 3rd trimester of pregnancy	Atmospheric pollutants	None	4.5	b	−33.4 (−66.3; −0.6)	0.046

CI, Confidence interval of the coefficient estimate; ICC, intra-class coefficient of correlation; IQR, inter-quartile range of the (normalized and corrected for measurement error) exposure variable.

^aEstimates are given as a change in mean birth weight (g) for each inter-quartile range (defined over all observations) increase in (normalized and corrected for measurement error) exposure. Only exposures with an uncorrected P-value < 5% are reported. Associations were adjusted for gestational duration (simple and quadratic terms), sex of the newborn, parity, maternal height, maternal weight before pregnancy (using a broken stick model with a knot at 60 kg), maternal smoking during the second trimester of pregnancy, maternal education, season of conception and cohort (fixed effect variable).

^bAtmospheric pollutants were not assumed to suffer from classical-type measurement error; no measurement error correction based on the ICC was applied.