Socioeconomic status and vitamin D deficiency among women of childbearing age: a population-based, case-control study in rural northern China

Shiqi Lin; Lifang Jiang; Yuan Zhang; Jian Chai; Jiajia Li; Xinming Song; Lijun Pei

doi:10.1136/bmjopen-2020-042227

Socioeconomic status and vitamin D deficiency among women of childbearing age: a population-based, case-control study in rural northern China

BMJ Open. 2021 Mar 22;11(3):e042227. doi: 10.1136/bmjopen-2020-042227.

Authors

Shiqi Lin^#¹, Lifang Jiang^#², Yuan Zhang^#¹, Jian Chai², Jiajia Li¹, Xinming Song³, Lijun Pei³

Affiliations

¹ Institute of Population Research/China Center on Population Health and Development, Peking University, Beijing, China.
² National Health Commission Key Laboratory of Birth Defects Prevention, Henan Key Laboratory of Population Defects Prevention, Zhengzhou, Henan, China.
³ Institute of Population Research/China Center on Population Health and Development, Peking University, Beijing, China pei_lj@pku.edu.cn xmsong@pku.edu.cn.

^# Contributed equally.

Abstract

Objective: To explore the association between socioeconomic status (SES) and vitamin D deficiency/insufficiency of women of childbearing age in rural northern China.

Design: A population-based, case-control study was conducted.

Setting: Four counties of Henan Province, China from 2009 to 2010.

Participants: 1151 non-pregnant healthy women between 18 and 40 years old.

Primary and secondary outcome measures: Serum 25-hydroxyvitamin D (25(OH)D) levels were measured using high-performance liquid chromatography-tandem mass spectrometry. Vitamin D insufficiency was defined as serum 25(OH)D ≥20 ng/mL and <30 ng/mL, deficiency as ≥10 ng/mL and <20 ng/mL, and severe deficiency as <10 ng/mL. SES was measured separately by women's and their husbands' education level and occupation, household income and expenditure, as well as aggregately by SES index constructed with principal component analysis.

Results: The median serum 25(OH)D level was 20.90 (13.60-34.60) ng/mL, and the prevalence of vitamin D insufficiency, deficiency and severe deficiency was 20.16%, 31.80% and 15.99%, respectively. After adjustment, household annual income <¥10 000 was associated with increased risk of vitamin D insufficiency (adjusted OR (aOR): 2.10, 95% CI 1.41 to 3.14), deficiency (aOR: 1.58, 95% CI 1.09 to 2.29) and severe deficiency (aOR: 2.79, 95% CI 1.78 to 4.38); inadequate household income for expenditure was associated with elevated risk of vitamin D insufficiency (aOR: 1.66, 95% CI 1.08 to 2.54) and deficiency (aOR: 1.81, 95% CI 1.26 to 2.62); low SES index was associated with elevated risk of vitamin D insufficiency (aOR: 2.40, 95% CI 1.52 to 3.80) and deficiency (aOR: 1.64, 95% CI 1.08 to 2.50); and both middle and low SES index were associated with increased risk of vitamin D severe deficiency (aOR: 1.70, 95% CI 1.02 to 2.84; aOR: 2.45, 95% CI 1.45 to 4.14).

Conclusions: Lower SES was associated with higher risk of vitamin D deficiency/insufficiency in women of childbearing age in rural northern China. More should be done to explore potential mechanisms and to narrow down SES inequalities in vitamin D status.

Keywords: nutrition & dietetics; public health; social medicine.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adolescent
Adult
Case-Control Studies
China / epidemiology
Female
Humans
Prevalence
Risk Factors
Rural Population
Social Class
Vitamin D
Vitamin D Deficiency* / epidemiology
Young Adult

Substances

Vitamin D