title: Effect of maternal smoking on birth weight of twins: a study from the Dutch Twin Register.
abstract: Since twins weigh about 20% less than singletons at birth, maternal smoking may be a more severe risk for them than for singletons. Therefore, the effect of maternal smoking during pregnancy on birth weight was investigated in a group of 5376 twins. All necessary information was collected by a questionnaire filled out by the mother of the twins. Gestational age explains more than 75% of the variance in birth weight. Other effects were tested with gestational age as a covariate. Apart from zygosity (DZ twins weigh more than MZ twins), birth order (first born twins weigh more than second born twins) and sex (boys weigh more than girls), there was a very significant birth weight reducing effect (more than 8%) maternal smoking as well as a significant influence of maternal age (young mothers give birth to smaller children). There were no interactions with maternal smoking.
authors.affiliation: Department of Physiological Psychology, Free University, Amsterdam, Netherlands.
authors.forename: J F
authors.initials: JF
authors.lastname: Orlebeke
authors.forename: D I
authors.initials: DI
authors.lastname: Boomsma
authors.forename: G C
authors.initials: GC
authors.lastname: Van Baal
authors.forename: O P
authors.initials: OP
authors.lastname: Bleker
mesh_terms: D001724:Birth Weight; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008423:Maternal Age; D008425:Maternal Behavior; D008431:Maternal-Fetal Exchange; D009426:Netherlands; D011247:Pregnancy; D012907:Smoking; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic