“…However, upon accounting for potential confounders, the effect diminished, yet remained statistically significant [hazard ratio 1.13, 95% CI, 1.03 to 1.25, and hazard ratio 1.11, 95% CI, 1.06 to 1.165] 16 . Nevertheless, when only studies using a sibling-matched design were analysed, this meta-analysis concluded that there was no significant association (hazard ratio 1.07, 95% CI, 0.99 to 1.16), 13,16 whereas another demonstrated a significant association in sibling-matched designed studies [hazard ratio 1.10, 95% CI, 1.02 to 1.18], 13 with, however, no dose–response effect. It was concluded that the small statistically significant association between LEA and ASD may be elucidated by selection bias and residual (unmeasured) confounders, such as genetic factors 16 …”