Mean difference [95% CI] in birth measurements of children born to non-smoking mothers, comparing those where the child's grandmother had smoked with those who had not.

The number of individuals in each analysis are shown in round brackets.aAdjusted for maternal parity, maternal education, partner smoked at start of pregnancy and gestation of study child.[N.B. the data for birth length and head circumference are given in cm x 100 so as to aid interpretation].