Effects of grandmothers' smoking in pregnancy on birth weight: intergenerational cohort study.
OBJECTIVE
To investigate the influences on birth weight of maternal smoking during pregnancy across generations.


METHODS
Intergenerational cohort study.


METHODS
Members of the 1958 birth cohort and their offspring and mothers.


METHODS
England, Scotland, and Wales.


METHODS
Birth weight.


RESULTS
Information on grandmothers' smoking during pregnancy was available for 9028 singleton offspring of 4302 female cohort members. Assuming heritable transmission through the intergenerational association, grandmothers' smoking was predicted to result in a 34 g reduction (95% confidence interval -41 g to -28 g) in the birth weight of grandchildren. Random effects models showed a negative association between grandmothers' smoking and birth weight of grandchildren (beta regression coefficient -24 g, -50 g to 3 g), but this effect was eliminated after adjustment for maternal smoking (0 g, -26 g to 26 g). No association was evident among the offspring of non-smoking mothers (n = 6105; 14 g, -17 g to 46 g), and after adjustment for maternal birth weight, adult height and body mass index, grandmothers' smoking was positively associated with the birth weight of grandchildren (45 g, 10 g to 80 g).


CONCLUSIONS
Deficits in mothers' birth weight attributable to their mother smoking was not evident in the grandchildren.
Hyppönen
Elina
E
Centre for Paediatric Epidemiology and Biostatistics, Institute of Child Health, London WC1N 1EH. e.hypponen@ich.ucl.ac.uk
Smith
George Davey
GD
Power
Chris
C
D000328:Adult; D001724:Birth Weight / Q000235:genetics*; D015331:Cohort Studies; D016001:Confidence Intervals; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D016014:Linear Models; D009035:Mothers / Q000706:statistics & numerical data*; D010375:Pedigree; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D012907:Smoking / Q000009:adverse effects* / Q000235:genetics