Maternal cigarette smoking during pregnancy. A risk factor for childhood strabismus
R. B. Hakim and J. M. Tielsch
Dana Center for Preventive Ophthalmology, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Md.
Strabismus is a common ophthalmologic disorder in children that can result
in permanent visual loss. A population-based case-control study was
conducted to investigate the association between childhood strabismus and
prenatal risk factors including maternal smoking. All incident cases of
strabismus diagnosed during a 21-month period, from January 1, 1985, to
September 30, 1986, in nine metropolitan area pediatric ophthalmology
centers were selected for study (n = 377). Controls were children born on
the same day and in the same hospital as the cases (n = 377). Data
collection included an interview with the biologic mother and abstraction
of obstetric and neonatal birth records. Cigarette smoking was associated
with esotropia and but not exotropia for those women who smoked throughout
pregnancy (odds ratio, 1.8, 95% confidence interval, 1.1 to 2.8, and odds
ratio, 1.4, 95% confidence interval, 0.6 to 3.1, respectively). The
relative risk for strabismus was not elevated for women who quit smoking
before pregnancy or during pregnancy, nor was there evidence of a dose
response. The effect of maternal smoking on risk of esotropia was modified
by birth weight and gestational age. The association of maternal smoking
throughout pregnancy and esotropia was strongest for children who weighed
less than 2500 g (odds ratio, 8.2, 95% confidence interval, 1.1 to 62.7)
and 3500 g or more at birth (odds ratio, 5.6, 95% confidence interval, 2.1
to 15.4). Exposure to secondary smoke during pregnancy increased the risk
of strabismus only when the mother smoked.
