Is the association of maternal smoking and pregnancy-induced hypertension dependent on fetal growth?
OBJECTIVE
The risk of pregnancy-induced hypertension (PIH) is decreased by smoking, but the mechanisms remain unclear. Our objective was to determine whether this association is dependent on decreased fetal growth.


METHODS
A population-based, retrospective cohort study in the United States was performed consisting of nulliparous women who delivered a singleton birth (n = 8,025,295) between 1995 and 2002. Fetal growth was defined as birthweight for gestational age and characterized as less than 1, 1-2, 3-4, 5-9, 10-19, ..., 90 or greater centiles. Risk and relative risk of PIH before and after adjusting for confounders were estimated.


RESULTS
Smoking was associated with decreased risk of PIH with up to a 46% decreased risk of PIH for growth-restricted babies (less than the 10th centile). This association, however, decreased with increasing birthweight centile and was nonsignificant at 20th or greater centile among heavy smokers, at 60th or greater centile for moderate, and 80th or greater centile for light smokers.


CONCLUSIONS
Smoking was primarily associated with decreased risk of PIH among growth-restricted babies.
Peltier
Morgan R
MR
Division of Maternal-Fetal Medicine, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Medicine and Dentistry New Jersey-Robert Wood Johnson Medical School, New Brunswick, NJ 08901, USA.
Ananth
Cande V
CV
D000328:Adult; D001724:Birth Weight / Q000502:physiology; D015331:Cohort Studies; D005260:Female; D047109:Fetal Development / Q000502:physiology*; D005317:Fetal Growth Retardation / Q000503:physiopathology*; D006801:Humans; D046110:Hypertension, Pregnancy-Induced / Q000453:epidemiology*; D011247:Pregnancy; D012189:Retrospective Studies; D012907:Smoking / Q000453:epidemiology* / Q000503:physiopathology*; D014481:United States / Q000453:epidemiology