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Does Vitamin D Deficiency Increase the Risk of Mother-to-child HIV Transmission?

Having a low level of vitamin D may increase the odds that HIV positive women will transmit the virus to their babies during pregnancy, delivery, or breast-feeding, according to a study conducted in Tanzania and reported in the August 12, 2009 advance online issue of the Journal of Infectious Diseases.

Saurabh Mehta from the Harvard School of Pubic Health and colleagues performed an observational analysis to examine the association between vitamin D levels and pregnancy outcomes and child mortality.

In addition to its well-known effect in promoting bone health, vitamin D is a strong immunomodulator, the investigators noted, and may protect against adverse pregnancy outcomes including mother-to-child transmission of HIV. Some prior research suggests that adequate vitamin D promotes good fetal growth and development.

The present study included 884 HIV positive pregnant women participating in a vitamin supplementation trial in Tanzania. About 80% had asymptomatic HIV disease. The women received supplements starting 12 weeks into pregnancy, but these did not include vitamin D.

Results

• No association was observed between maternal vitamin D levels and adverse pregnancy outcomes, including premature delivery and low birth-weight babies.
• In a multivariate analysis, however, mothers with a low vitamin D level (< 32 ng/mL) had a 50% higher risk of transmitting HIV to their infants, as determined 6 weeks after birth.
• Among babies who remained uninfected at 6 weeks, those born to mothers with low vitamin D levels were twice as likely to become infected with HIV during breast-feeding.
• After 24 months of follow-up, children born to women with low vitamin D levels had a 46% higher overall risk of HIV infection.
• Rates of mother-to-child HIV transmission increased as vitamin D levels decreased, and women with the lowest levels had the greatest risk.
• Furthermore, children born to women with a low vitamin D level had a 61% higher risk of dying during the follow-up period.

Based on these findings, the study authors concluded, "If found to be efficacious in randomized trials, vitamin D supplementation could prove to be an inexpensive method of reducing the burden of HIV infection and death among children, particularly in resource-limited settings."

In their discussion, they suggested that since vitamin D is known to contribute to development of the fetal immune system, babies born to women with higher vitamin D levels might have stronger immune systems that make them more resistant to HIV infection.

Departments of Epidemiology, Nutrition, Biostatistics, and Global Health and Population, Harvard School of Public Health, Boston, MA; Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA; Departments of Internal Medicine, Pediatrics, and Community Health, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania.

9/01/09

Reference

S Mehta, DJ Hunter, FM Mugusi, and others. Perinatal Outcomes, Including Mother-to-Child Transmission of HIV, and Child Mortality and Their Association with Maternal Vitamin D Status in Tanzania. Journal of Infectious Diseases. August 12, 2009 (Epub ahead of print).