Ng S, et al. - In this Asian longitudinal study, researchers investigated the association between smoking and environmental tobacco smoke (ETS) exposure in pregnancy, and longitudinal measures of offspring length/height from birth to 60 months using circulating cotinine as an objective biomarker. Maternal plasma cotinine at 26-28 weeks’ gestation was measured by LC/MS/MS in 969 maternal-offspring dyads from the GUSTO cohort. Findings revealed the association of high prenatal cotinine with persistently shorter stature in offspring from birth and into early childhood, whilst there appeared no correlation between low prenatal cotinine levels and ETS exposure.