Optimizing ultraviolet B radiation exposure to prevent vitamin D deficiency among pregnant women in the tropical zone: report from cohort study on vitamin D status and its impact during pregnancy in Indonesia

Abstract

Background Vitamin D deficiency during pregnancy carries potential threat to fetal well being. Natural conversion of vitamin D in the skin can be facilitated by direct ultra violet B (UVB) radiation, but the effect is reduced by wearing umbrellas, clothes, or sunblock cream. Muslim women wear hijab that allows only face and hands to be seen. With increasing proportion of muslim women wearing hijab and the lack of vitamin D fortification and fish consumption in Indonesia, it poses a problem for vitamin D deficiency among pregnant women. This study aimed at finding the best timing of UVB exposure and the duration of exposure which can be suggested to prevent vitamin D deficiency among pregnant women, for those wearing hijab or not. Methods This study recruited 304 pregnant women in the first trimester, 75–76 women from 4 cities of the most populated province, West Java, Indonesia which represented 70–80% percent of pregnancy per year. A 3-day notes on duration, time and type of outdoor activity and the clothing wore by the women were collected. UVB intensity radiation were obtained. Calculation on body surface area exposed to direct UVB radiation and UVB radiation intensity were done. Measurement of vitamin D level in sera were done on the same week. Results The median of maternal sera vitamin D level was 13.6 ng/mL and the mean exposed area was around 0.48 m2 or 18.59% of total body surface area. Radiation intensity reached its peak around 10.00 and 13.00, but the mean duration of exposure to UVB during this window was lower than expected. Significant correlation was found between maternal sera vitamin D level and exposed body surface area (r = 0.36, p < 0.002) or percentage of exposed body surface (r = 0.39, p < 0.001) and radiation intensity (r = 0.15, p = 0.029). Further analysis showed that duration of exposure to UVB should be longer for pregnant women wearing hijab as compared to women without hijab. Conclusion This study suggested that the best timing to get UVB exposure was between 10.00–13.00, with longer duration for women wearing hijab (64.5 vs 37.5 min) of continuous exposure per day. Electronic supplementary material The online version of this article (10.1186/s12884-019-2306-7) contains supplementary material, which is available to authorized users.

The prevalence and determinants of vitamin D deficiency in Indonesian infants at birth and six months of age

“…As such, there are recommendations for pregnant women relating to sun exposure in Indonesia, i.e. continuous sun exposure between 10 am to 1 pm for 30 minutes (or 60 minutes for veiled women) per day [31]. The findings here support the recommendations that pregnant women have adequate sun exposure, as higher sun exposure reduced the risk of vitamin D deficiency at birth.…”

Sunlight exposed body surface area is associated with serum 25-hydroxyvitamin D (25(OH)D) level in pregnant Minangkabau women, Indonesia

“…The estimation of dietary intake, sunlight exposure, and sunscreen use are approximations. Nevertheless, our findings are in line with previous studies in Indonesia [9,10], strengthening the epidemiological evidence that VDD is prevalent in Indonesian women, and the lack of sunlight exposure is an essential determinant for VDD. Fig.…”

“…A study in Kenya, a tropical country, showed that 51% of women had insufficient (< 75 nmol/L), and 21% had deficient serum 25(OH)D level (< 50 nmol/L) [8]. With the high prevalence of VDD in women reported in sunny countries [8][9][10], VDD in pregnant women needs particular attention because of the potential unwanted birth outcome.…”

Cord blood vitamin D is correlated with problem solving domain in early childhood neurodevelopment: A Cohort Study on Vitamin D Status and Its Impact during Pregnancy and Childhood in Indonesia

“…The provision of vitamin D supplementation in Indonesia is still difficult as a standard due to the high price. As an alternative, exposing 18.59% of body surface area to sunlight for 37.5 minutes per day especially between 10.00−13.00 is proven to be an effective method to meet daily vitamin D requirements, as reported by Judistiani et al 25 The limitation of this study was not report, several factors that could have affected vitamin D levels and neurodevelopmental status at the age of two year old, such as parenting style and complementary food given after the age of 6 months old. Future long-term cohort studies taking these factors into consideration or randomized clinical trial giving vitamin D supplementation is required.…”