title: Prenatal factors for childhood blood pressure mediated by intrauterine and/or childhood growth?
abstract: OBJECTIVE
  Some prenatal factors may program an offspring's blood pressure, but existing evidence is inconclusive and mechanisms remain unclear. We examined the mediating roles of intrauterine and childhood growth in the associations between childhood systolic blood pressure (SBP) and 5 potentially modifiable prenatal factors: maternal smoking during pregnancy; prepregnancy BMI; pregnancy weight gain; chronic hypertension; and preeclampsia-eclampsia.
  
  
  METHODS
  The sample contained 30 461 mother-child pairs in the Collaborative Perinatal Project. Prenatal data were extracted from obstetric forms, and children's SBP was measured at 7 years of age. Potential mediation by intrauterine growth restriction (IUGR) and childhood growth was examined by the causal step method.
  
  
  RESULTS
  Heavy maternal smoking during pregnancy was significantly associated with higher offspring SBP (adjusted mean difference versus nonsmoking: 0.73 mm Hg [95% confidence interval (CI): 0.32-1.14]), which attenuated to null (0.13 [95% CI: -0.27-0.54]) after adjustment for changes in BMI from birth to 7 years of age. Prepregnancy overweight-obesity was significantly associated with higher offspring SBP (versus normal weight: 0.89 mm Hg [95% CI: 0.52-1.26]), which also attenuated to null (-0.04 mm Hg [95% CI: -0.40-0.31]) after adjustment for childhood BMI trajectory. Adjustment for BMI trajectory augmented the association between maternal pregnancy weight gain and offspring SBP. Adjustment for childhood weight trajectory similarly changed these associations. However, all these associations were independent of IUGR.
  
  
  CONCLUSIONS
  Childhood BMI and weight trajectory, but not IUGR, may largely mediate the associations of maternal smoking during pregnancy and prepregnancy BMI with an offspring's SBP.
authors.affiliation: Epidemiology Section, Department of Community Health, Brown University, 121 South Main St, Providence, RI 02912, USA. xiaozhongwen@hotmail.com
authors.forename: Xiaozhong
authors.initials: X
authors.lastname: Wen
authors.forename: Elizabeth W
authors.initials: EW
authors.lastname: Triche
authors.forename: Joseph W
authors.initials: JW
authors.lastname: Hogan
authors.forename: Edmond D
authors.initials: ED
authors.lastname: Shenassa
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Buka
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D015992:Body Mass Index; D002648:Child; D002657:Child Development / Q000502:physiology*; D002675:Child, Preschool; D005260:Female; D047109:Fetal Development / Q000502:physiology*; D005500:Follow-Up Studies; D006801:Humans; D006973:Hypertension / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology*; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D018811:Maternal Exposure / Q000009:adverse effects*; D011225:Pre-Eclampsia / Q000453:epidemiology / Q000503:physiopathology*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000503:physiopathology*; D012907:Smoking / Q000009:adverse effects*; D014481:United States / Q000453:epidemiology; D055815:Young Adult