Maternal Vitamin D Status and Its Related Factors in Pregnant Women in Bangkok, Thailand

Abstract

BackgroundThere are few data focusing on the prevalence of vitamin D deficiency in tropical countries. ObjectivesWe determined the vitamin D status in pregnant women and examined the factors associated with vitamin D deficiency. Design and MethodsA cross-sectional study of 147 pregnant Thai women aged 18–45 years at Siriraj Hospital (a university hospital in Bangkok, Thailand) was undertaken. Clinical data and plasma levels of 25-hydroxyvitamin D [25(OH)D], intact parathyroid hormone (iPTH), calcium, albumin, phosphate and magnesium were obtained in pregnant women at delivery. ResultsThe prevalence of hypovitaminosis D [defined as 25(OH)D <75 nmol/L] in pregnant women at delivery was 75.5% (95% confidence interval (CI), 67.7–82.2%). Of these, vitamin D insufficiency [defined as 25(OH)D 50–74.9 nmol/L] was found in 41.5% (95% CI, 33.4–49.9%) and vitamin D deficiency [25(OH)D <50 nmol/L] was found in 34.0% (95% CI, 26.4–42.3%) of women. The mean 25(OH)D concentration was 61.6±19.3 nmol/L. The correlation between 25(OH)D and iPTH was weak (r = –0.29, P<0.01). Factors associated with vitamin D deficiency by multiple logistic regression were: pre-pregnancy body mass index (BMI in kg/m2, odds ratio (OR), 0.88, 95% CI 0.80–0.97, P = 0.01) and season of blood collection (winter vs. rainy, OR, 2.62, 95% CI 1.18–5.85, P = 0.02). ConclusionsVitamin D deficiency is common among pregnant Thai women. The prevalence of vitamin D deficiency increased in women who had a lower pre-pregnancy BMI and whose blood was collected in the winter. Vitamin D supplementation may need to be implemented as routine antenatal care.

Vitamin D status and the prevalence of deficiency in lactating women from eight provinces and municipalities in China

“…To our knowledge this is the first large-scale study on vitamin D status and analysis on associated risk factors for vitamin D deficiency of lactating women in China. The median of serum 25(OH)D was only 15.8 nmol/L which was much lower than that of the cutoff point (30nmol/L) to define vitamin D deficiency and also much lower than the means of lactating women reported previously in US [31], Thailand [30] and United Arab Emirates [32], and similar to those reported in lactating women living in Lahore [7]. Therefore, our results indicated that lactating women would be vulnerable groups suffered from vitamin D deficiency because such populations usually avoid direct exposure to sunlight and consume fewer foods naturally rich in vitamin D and national fortification of food with vitamin D has not been implemented in China.…”

“…It has been reported that vitamin D deficiency is a major public health concern worldwide in all age groups particular in special physiological stage such as pregnancy and lactation[29], even in the populations living in those countries with low latitude, where it was generally assumed that UV radiation was adequate to prevent vitamin D deficiency, and in industrialized countries, where vitamin D fortification has been implemented for decades [14, 18, 20, 30]. However, few studies had been conducted in lactating women at national level.…”

“…The concentration of serum 25(OH)D was affected by many factors such as season or the extent of exposure to UV-B radiation, use of vitamin D supplements, intake of diets rich in vitamin D and use of estrogen contraceptives as well as the difference between urban and rural areas (Table 3 and Table 4) [30, 33–36]. There was higher serum vitamin D level of lactating women in urban area than in rural area in Beijing, which might be due to the difference of multivitamin supplement uses as well as the intake of food rich in vitamin D [33].…”

“…The opposite result could be explained by the proportion of higher-educated lactating women who usually had work indoors and had less outdoor activities [30]. It has been reported that the mean level of 25(OH)D was associated with household income [30].…”

“…The opposite result could be explained by the proportion of higher-educated lactating women who usually had work indoors and had less outdoor activities [30]. It has been reported that the mean level of 25(OH)D was associated with household income [30]. Our study showed that serum 25(OH)D level could be increased by about 4% following 10 000 CNY increase of per capita income (Table 4) which was contrary to the study in pregnant women in Thailand [30].…”