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Open Access Research article

BMI mediates the association between low educational level and higher blood pressure during pregnancy in Japan

Seung Chik Jwa12, Takeo Fujiwara1*, Akira Hata2, Naoko Arata3, Haruhiko Sago4 and Yukihiro Ohya5

Author affiliations

1 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

2 Department of Public Health, Chiba University Graduate School of Medicine, Chiba, Japan

3 Department of Women’s Health, National Center for Child Health and Development, Tokyo, Japan

4 Center for Maternal-Fetal and Neonatal Medicine, National Center for Child Health and Development, Tokyo, Japan

5 Department of Medical Specialties, National Center for Child Health and Development, Tokyo, Japan

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Citation and License

BMC Public Health 2013, 13:389  doi:10.1186/1471-2458-13-389

Published: 25 April 2013

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.

Conclusion

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.

Keywords:
Socioeconomic status; Pregnancy; Blood pressure; Educational level; Pregnancy-induced hypertension