Objective To evaluate the association of second-hand smoke exposure of
pregnant mothers using urine cotinine with the neurodevelopment of their
children at 18 months of age in the mother-child cohort in Crete (Rhea
Study).
Study design Selected participants were Greek mothers with singleton
pregnancies, had never smoked, and had available urine cotinine
measurements in pregnancy, and their children for whom a
neurodevelopmental assessment was completed. We performed face-to-face
interviews twice during pregnancy and postnatally, and assessed
children’s neurodevelopment at 18 months of age using the Bayley Scales
of Infant and Toddler Development, Third Edition. We used linear
regression and generalized additive models.
Results Of 599 mothers, 175 (29%) met the inclusion criteria. Maternal
urine cotinine levels were low (mean: 10.3 ng/mL, SD: 11.7 ng/mL).
Reported passive smoking from different sources was strongly associated
with urine cotinine levels. A negative association was observed between
cotinine levels in pregnancy and child’s gross motor function (beta =
-3.22 per 10 ng/mL, 95% CI -5.09 to -1.34) after adjusting for factors
potentially associated with neurodevelopment; results were similar in
both sexes. A negative association was also observed for cognitive and
receptive communication scales but the effect was small and not
statistically significant.
Conclusions Maternal exposure during pregnancy to second-hand smoke
measured through urine cotinine was associated with a decrease in gross
motor function among 18-month-old children, even at low levels of
exposure