title: Does maternal weight gain in pregnancy have long-term effects on offspring adiposity? A sibling study in a prospective cohort of 146,894 men from 136,050 families.
abstract: BACKGROUND
  A small number of relatively small studies have found greater gestational weight gain to be associated with greater offspring body mass index (BMI; in kg/m(2)), but whether this association is caused by intrauterine mechanisms or by shared genetic and environmental risk factors for adiposity is unclear.
  
  
  OBJECTIVE
  The objective was to examine the association of greater maternal weight gain (MWG; postnatal weight minus weight at the first antenatal clinic assessment) with greater offspring BMI and to explore whether any observed association is explained by intrauterine mechanisms.
  
  
  METHODS
  This was a prospective cohort study that used record linkage data (n = 146,894 individuals from 136,050 families). To compare the within-sibling and between-nonsibling associations, we used fixed- and between-cluster linear regression models.
  
  
  RESULTS
  Associations of MWG with later offspring BMI differed by the mother's early-pregnancy overweight or obesity status (P for interaction <0.0001). MWG was positively associated with BMI at a mean age of 18 y in the offspring of normal-weight women but only between unrelated men (0.07; 95% CI: 0.06, 0.07) per 1-kg greater MWG; no within-sibling association (0.00; 95% CI: -0.02, 0.02) per 1-kg greater MWG was found. In contrast, in overweight and obese women we found a within-sibling association (0.06; 95% CI: 0.01, 0.12) and an association between unrelated men (0.02; 95% CI: 0.01, 0.03) per 1-kg greater MWG.
  
  
  CONCLUSIONS
  In normal-weight mothers, most of the association between MWG and later offspring BMI is explained by shared familial (genetic and early environmental) characteristics, whereas evidence indicates a contribution of intrauterine mechanisms in overweight and obese women.
authors.affiliation: MRC Centre for Causal Analyses in Translational Epidemiology, School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom. d.a.lawlor@bristol.ac.uk
authors.forename: Debbie A
authors.initials: DA
authors.lastname: Lawlor
authors.forename: Paul
authors.initials: P
authors.lastname: Lichtenstein
authors.forename: Abigail
authors.initials: A
authors.lastname: Fraser
authors.forename: Niklas
authors.initials: N
authors.lastname: Långström
mesh_terms: D050154:Adiposity; D015992:Body Mass Index; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D011446:Prospective Studies; D035781:Siblings; D015430:Weight Gain