Differences in mean verbal IQ score at age 8 according to OME/HL group (up to 5 years).

aA negative coefficient indicates that IQ is lower in the OME/HL group compared to the unaffected reference group. bAdjusted for maternal education level, housing tenure, parental social class, maternal age, parity, smoking during 1st 3 months of pregnancy, smoking last 2 weeks of pregnancy, birthweight, gestational age, sex of child. cAdjusted for maternal education level, housing tenure, parental social class, maternal age, parity, smoking during 1st 3 months of pregnancy, smoking last 2 weeks of pregnancy, birthweight, gestational age, sex of child, home and parenting scores. dp-value for testing the effect of each OME/HL group vs the unaffected reference group. ep-value for linear trend in effect size across groups.