Low vitamin D is associated with preterm birth and low birth weight infants in a cohort of pregnant HIV-infected women sampled over a 23-year period

To evaluate the impact of low maternal vitamin D levels in pregnant HIV-infected women on the incidence of preterm birth (PTB), low birth weight (LBW) and small-for-gestational age (SGA) infants Retrospective cohort study evaluating the impact of low maternal vitamin D levels on perinatal outcomes among HIV-infected women receiving prenatal care at a major urban HIV perinatal center. Comprehensive vitamin D panels (1,25-dihydroxyvitamin D (1,25(OH)2D), 25-hydroxyvitamin D (25(OH)D), free and bioavailable fractions) were performed on maternal plasma samples collected and stored near the time of delivery (births 1991-2014) as part of a natural history study. Multivariate analyses controlled for potential confounders including indices of HIV disease severity and control. The cohort included 366 mother-baby pairs, of which 13.7% (N=50) were delivered preterm (<37 weeks of gestation), 10.4% (N=38) were LBW (<2500 grams), and 2.3% (N=10) were SGA (birthweight <10th percentile). Higher 1,25(OH)2D levels, the active form of vitamin D, were protective against PTB (OR 0.92 [95% CI 0.85-0.98], p=0.01) and LBW (OR 0.91 [95% CI 0.84-0.99], p=0.03). The associations remained significant in multivariate analyses for both PTB (OR 0.92 [95% CI 0.84-1.0], p=0.04) and LBW (OR 0.91 [95% CI 0.84-0.99], p=0.03), controlling for maternal demographics, mode of delivery, HIV treatment regimen, and measures of HIV disease control. Correlates of vitamin D levels included maternal race, season, CD4, HIV viral load, and antiretroviral regimen. CD4 counts <200 were independently associated with preterm birth (p=0.002). Maternal HIV viral load was a significant correlate of both 1,25(OH)D2 and 25(OH)D, but was not itself associated with the obstetric outcomes. Lower vitamin D levels are associated with HIV disease severity in pregnant HIV-infected women. Lower levels of 1,25-dihydroxyvitamin D, the active circulating form of vitamin D, were independently associated with an increased risk of preterm birth and LBW infants in this cohort.