title: BMI mediates the association between low educational level and higher blood pressure during pregnancy in Japan.
abstract: BACKGROUND
  Research investigating the association between socioeconomic status (SES) and blood pressure (BP) during pregnancy is limited and its underlying pathway is unknown. The aim of this study was to investigate the mediators of the association between educational level as an indicator of the SES and BP in early and mid-pregnancy among Japanese women.
  
  
  METHODS
  Nine hundred and twenty-three pregnant women in whom BP was measured before 16 weeks and at 20 weeks of gestation were enrolled in this study. Maternal educational levels were categorized into three groups: high (university or higher), mid (junior college), and low (junior high school, high school, or vocational training school).
  
  
  RESULTS
  The low educational group had higher systolic (low vs. high, difference = 2.39 mmHg, 95% confidence interval [CI]: 0.59 to 4.19) and diastolic BP levels (low vs. high, difference = 0.74 mmHg, 95% CI: -0.52 to 1.99) in early pregnancy. However, the same associations were not found after adjustment for pre-pregnancy body mass index (BMI). BP reduction was observed in mid-pregnancy in all three educational groups and there was no association between educational level and pregnancy-induced hypertension.
  
  
  CONCLUSIONS
  In Japanese women, the low educational group showed higher BP during pregnancy than the mid or high educational groups. Pre-pregnancy BMI mediates the association between educational level and BP.
authors.affiliation: Department of Social Medicine, National Research Institute for Child Health and Development, National Center for Child Health and Development, 2-10-1, Setagaya-ku, Tokyo, Japan.
authors.forename: Seung Chik
authors.initials: SC
authors.lastname: Jwa
authors.forename: Takeo
authors.initials: T
authors.lastname: Fujiwara
authors.forename: Akira
authors.initials: A
authors.lastname: Hata
authors.forename: Naoko
authors.initials: N
authors.lastname: Arata
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Sago
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Ohya
mesh_terms: D000328:Adult; D015992:Body Mass Index; D002908:Chronic Disease / Q000453:epidemiology; D004522:Educational Status; D005260:Female; D007722:Health Knowledge, Attitudes, Practice; D006801:Humans; D046110:Hypertension, Pregnancy-Induced / Q000453:epidemiology*; D008019:Life Style; D011247:Pregnancy; D011446:Prospective Studies; D012923:Social Class; D014041:Tokyo / Q000453:epidemiology; D015430:Weight Gain / Q000502:physiology