Reply to Equils and Hewison

Abstract

To the Editor-We read with great interest the letter by Equils and Hewison [1] in reference to our article on vitamin D and perinatal outcomes, including mother-tochild transmission of human immunodeficiency virus (HIV), and child mortality [2].The authors noted that the women in our cohort had far higher levels of vitamin D than women in a study in the United States had [3]. However, Tanzania, the setting of our study, is only 6Њ south of the equator, and sunlight is in abundance throughout the year. In fact, we were surprised that almost 40% of the women in our cohort had 25-hydroxyvitamin D levels of !32 ng/mL (80 nmol/L). However, similar results were observed among a cohort of patients with tuberculosis in Tanzania by another group of investigators [4]. Therefore, we may expect to find vitamin D levels that are closer to those observed in our study in urban settings in tropical countries, and the levels in more temperate climates may be closer to those found in Pittsburgh, Pennsylvania.We agree with the authors that there is increasing evidence to support the biological plausibility for a role of vitamin D in enhancing placental immunity and the immune system of the newborn. It will be important to examine the safety and efficacy of vitamin D supplementation among pregnant women in relation to the incidence and severity of HIV infection, tuberculosis, and other infections among their offspring, particularly in resource-limited settings. References 1. Equils O, Hewison M. A role for vitamin D in placental immunology. J Infect Dis 2010; 201(12):1950-1951 (in this issue). 2. Mehta S, Hunter DJ, Mugusi FM, et al. Perinatal outcomes, including mother-to-child transmission of HIV, and child mortality and their association with maternal vitamin D status in Tanzania.