caa a22 4500 388059044 CHVBK 20180307125115.0 cr unu---uuuuu 161130e19980601xx s 000 0 eng 10.1375/twin.1.3.123 doi S1369052300000301 pii (NATIONALLICENCE)cambridge-10.1375/twin.1.3.123 Etiology of individual differences in birth weight of twins as a function of maternal smoking during pregnancy [Elektronische Daten] Birth weight is in large extent influenced by gestational age. In addition genetic and environmental factors determine intrauterine growth and birth weight. The contributions of these factors may be influenced by maternal smoking during pregnancy. We examined birth weight and maternal smoking in a sample of 2930 twin pairs from the Netherlands Twin Register using structural equation modelling. Gestational age accounted for 27-44% of the variance in birth weight. A lower variability of birth weight and a lower association of birth weight with gestational age was found in twins whose mothers smoked during pregnancy. The variance not associated with gestational age was independent of maternal smoking during pregnancy. A systematic smaller part of the variability in birth weight was associated with variability in gestational age in second born twins compared to first born twins. The heritability of interindividual differences in birth weight was modest (10% for twins with non-smoking mothers and 11% for twins with smoking mothers). Common environmental influences other than gestational age accounted for a slightly larger part of the variance not associated with gestational age (17-20%). Copyright © Cambridge University Press 1998 birth weight nationallicence genetics nationallicence gestational age nationallicence maternal smoking nationallicence twins nationallicence van Baal Caroline GM Vrije Universiteit, Amsterdam, The Netherlands. gcm.van.baal@psy.vu.nl Boomsma Dorret I. Vrije Universiteit, Amsterdam, The Netherlands. Twin Research Cambridge University Press 1/3(1998-06-01), 123-130 1369-0523 1:3<123 1998 1 THG https://doi.org/10.1375/twin.1.3.123 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1375/twin.1.3.123 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- van Baal Caroline GM Vrije Universiteit, Amsterdam, The Netherlands. gcm.van.baal@psy.vu.nl NATIONALLICENCE 700 1- Boomsma Dorret I. Vrije Universiteit, Amsterdam, The Netherlands NATIONALLICENCE 773 0- Twin Research Cambridge University Press 1/3(1998-06-01), 123-130 1369-0523 1:3<123 1998 1 THG CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge