Prevalence of vitamin D deficiency in exclusively breastfed infants at Charoenkrung Pracharak Hospital

ARTICLE HIGHLIGHTS

Research background

Vitamin D deficiency is a common problem in exclusively breastfed infants. Therefore, vitamin D supplementation in infants is suggested by various international medical organizations. Due to limited available data in Thailand, there is no local recommendation for routine vitamin D supplementation. Thus, this study investigated the prevalence of vitamin D deficiency and its associated factors in exclusively breastfed infants.

Research motivation

Due to the limited number of studies on this issue in Thailand, routine vitamin D supplementation for lactating mothers or infants has not been established. In South East Asia, the amount of sun exposure required to maintain normal vitamin D levels in infants remains unknown. Few researchers have recommended that infants wearing only a diaper should be exposed to sunlight for up to 30 min per week and those with full clothes and no hat should be exposed to sunlight for 2 h per week. In addition, Charoenkrung Pracharak Hospital is a tertiary hospital which is a famous friendly breastfeeding hospital in Thailand and has a high rate of delivery. How big of vitamin D deficiency is a valuable thing to figure out in order to set up a proper guideline.

Research objectives

This study aimed to investigate the prevalence of vitamin D deficiency and its associated factors in exclusively breastfed infants in Bangkok. This study could not represent the overall Thai baby because we did a study in Bangkok which is the capital city of Thailand. So, enrolling the participants from all provinces is needed to study in the future in order to make an accurate prevalence of vitamin D deficiency in exclusively breastfed infants in Thailand.

Research methods

This descriptive observational cross-sectional study assessed 109 4-month-old infants at Charoenkrung Pracharak Hospital from May 2020 to April 2021. The 25-OH vitamin D level of the infants was measured using an electrochemiluminescence binding assay. Vitamin D deficiency was defined as 25-OH level < 20 ng/mL, with vitamin D insufficiency 20-30 ng/mL. This study is the first to report on the sun index in infants in Thailand. Sun exposure is represented by the sun index, which is calculated from the exposed body surface area and the duration of exposure in hours per week. It was expected to be a protective factor. Sun index and maternal vitamin D supplementation data were collected and analyzed using the independent t-test, univariate logistic regression, and multivariate logistic regression to identify the associated factors.

Research results

This study shows the high prevalence of vitamin D deficiency and vitamin D insufficiency (35.78% and 33.03%, respectively). The mean serum 25-OH vitamin D levels in both groups were 14.37 ± 3.36 and 24.44 ± 3.29 ng/mL, respectively. The associated factors were maternal vitamin D supplementation and birth weight. supplementation which were analyzed with multivariate logistic regression and showed crude odds ratios were 0.26 (0.08–0.82) and 0.08 (0.01–0.45), respectively. Sun index did not correlate with the 25-OH vitamin D level in the exclusively breastfed infants (r = −0.002, P = 0.984). In addition, the sun index record form should be revised and recorded for at least 1 wk before collecting the blood to prevent the bias.

Research conclusions

Our results showed a high prevalence of vitamin D deficiency in exclusively breastfed infants which is the risk factor of vitamin D deficiency. Daily supplement of vitamin D in mothers was found to ameliorate vitamin D deficiency in infants while sun exposure in infants was inadequate to maintain vitamin D levels and was not correlated with vitamin D status. Although Thailand is rich in sunshine, the prevalence of vitamin D deficiency is high. Therefore, Thai medical organizations should establish guidelines for routine vitamin D supplementation in exclusively breastfed infants.

Research perspectives

The correlation of maternal vitamin D level, sun index, the dose of vitamin D supplement and vitamin level in exclusively breastfed infants should be evaluated in order to figure out the associated factors with vitamin D levels in infants. In addition, the vitamin D doses should be explored to set up proper vitamin D doses for prevention and treatment in exclusively breastfed infants who are diagnosed with vitamin D deficiency.