Vitamin D Status of Husbands of Pregnant Women in Dhaka, Bangladesh
Authors: Ruiter Lindsay , Shi Joy , Papp Eszter , Al Mahmud Abdullah , Gernand Alison , Roth Daniel 
Published: November 2023

Vitamin D deficiency is common among women of reproductive age in South Asia, and may be due to a range of factors including skin pigmentation, conservative dress, sun avoidance, and air pollution. However, these risk factors are challenging to measure precisely and often lack variability within study populations. Under the same household and environmental conditions, men may have greater skin exposure and time outdoors; however, there are few reports of men's vitamin D status in these settings. In a preliminary study of the effect of gender‐specific lifestyle factors on vitamin D status in Bangladesh, we aimed to describe the vitamin D status in a sample of pairs of pregnant women and their husbands (n=83) participating in an ongoing vitamin D supplementation trial. Among men, 25‐hydroxyvitamin D (25(OH)D) was measured in plasma; among women, 25(OH)D at trial enrolment (2nd trimester) was measured in plasma (n=22) or serum (n=61). In a separate but overlapping sample of pregnant women with serum 25(OH)D <80nmol/L (n=49), plasma 25(OH)D (19.5 ± 10.0 nmol/L) was linearly correlated with, but significantly lower than, concurrent serum 25(OH)D (24.4 ± 11.9 nmol/L; p<0.0001). We converted serum to plasma 25(OH)D using a linear correction formula (Plasma=0.892+0.753*Serum, R2=0.8) for the 61 women with serum only. All analyses accounted for the matched pair design.

50% of the men but only 23% of women spent ≥2 hours outdoors per day during daytime hours (n = 82, p=0.0007). 24% of men and 0% of women reported outdoor professions (p<0.0001). All serum/plasma samples were drawn from March to July 2014. Men were sampled 27.1 ± 19.9 days after their spouses, on average. Men's mean 25(OH)D (55.2 ±17.5 nmol/L) was significantly higher than women's (21.6 ±10.7nmol/L) after adjusting for calendar timing of serum/plasma sampling (mean difference = 30.7 nmol/L; p<0.0001). A significantly lower proportion of men (6.0%) were vitamin D deficient (25(OH)D<30nmol/L) vs women (21.7%; p<0.0001 after adjustment for calendar timing), and vitamin D sufficiency at the ≥40nmol/L and ≥50 nmol/L cut‐offs was significantly more common among men (73.8% and 60.7%, respectively) vs their spouses (9.6% and 0.0%, p<0.0001 for both comparisons after adjustment for calendar timing). In conclusion, men had substantially higher circulating 25(OH)D concentrations and lower risk of vitamin D deficiency than their pregnant spouses in Dhaka. Gender‐related lifestyle factors, rather than ethnic or environmental factors likely explain the high risk of vitamin D deficiency among women of reproductive age in Bangladesh. In the present study, pregnancy may also have directly reduced 25(OH)D (e.g., plasma volume expansion). Further research in an expanded study sample will explore specific factors that explain the gender discrepancy in vitamin D status in this setting, as well as the specific effect of pregnancy on circulating 25(OH)D.

Support or Funding Information

Bill and Melinda Gates Foundation