Vitamin D deficiency associated with reproductive factors in northern Iranian women: The PERSIAN Guilan Cohort Study (PGCS)

Abstract

Background: One of the public health concerns is Vitamin D deficiency. The aim of this study was to determine the prevalence of vitamin D inadequacy and to determine its reproductive factor correlates in northern Iranian women.

Methods: This study, conducted on 5096 females aged 35-70 years. The study was based on data from PERSIAN Guilan Cohort Study (PGCS), a prospective, population-based cohort study in Guilan, Iran. History of reproductive and gynecologic factors, including age at menarche, age at first marriage, number of pregnancies or live births, age at first pregnancy, duration of breastfeeding, number of abortions, age and type of menopause status, use of oral contraceptives or hormone replacement therapy, history of hysterectomy, tubectomy or oophorectomy and history of gestational diabetes and hypertension was collected. Serum 25(OH) vitamin D was measured.

Results: The mean 25(OH)-D concentration was 21.78 ng/mL, and 53.5% of women had vitamin D inadequacy. The multivariate analyses revealed that younger age (36-45 years) [>66 years adjusted odds ratio (aOR) = 2.1, 95% CI 1.7-2.7, 56-65 years aOR = 1.7, 95% CI 1.3-2.1 and 46-55 years aOR = 1.4, 95% CI 1.1-1.7], not consuming oral contraceptives [aOR = 1.1, 95% CI 1.05-1.3] and pre-menopausal status [aOR = 1.4, 95% CI 1.2-1.6] were significantly independently associated with vitamin D inadequacy.

Conclusion: Vitamin D inadequacy is common in northern Iranian women. The reproductive factors that independently correlated with vitamin D statues are oral contraceptive consumption and menopausal statue.

Keywords: PERSIAN Guilan cohort study; Reproductive factors; Vitamin D deficiency.