Neutrophil Count in African Mothers and Newborns and HIV Transmission Risk

Abstract

This study examined association of neutrophil counts in mothers and in newborns at risk for infant perinatal HIV infection in the Malawi BAN cohort. The timing of infant perinatal HIV infection was determined by a confirmed positive result on a PCR assay during the first 48 h of life (in utero transmission) or by 2 weeks of age (intrapartum transmission). Results showed that neutrophil counts in mothers and infants infected with HIV perinatally (119 infants) were lower that the counts of infants who were not infected perinatally (2250 infants). Almost all the infected infants (114) acquired their infection in utero, since mothers in the cohort started antiretroviral prophylaxis at the onset of labour. Infant white-cell and neutrophil counts were collected on the day of or the day after birth in 90.3% of cases, with no difference in timing between HIV-infected and uninfected infants. Higher neutrophil counts in the mother (risk ratio, 0.93; P=0.02) and in the newborn (risk ratio, 0.89; P<0.001) were associated with a lower risk of perinatal HIV infection. The association of infant neutrophil counts with perinatal HIV infection persisted after adjustment for maternal CD4+ levels, treatment with cotrimoxazole during pregnancy, infant sex and birth weight, and maternal log10 viral load (adjusted risk ratio, 0.88; P=0.03). Each incremental increase in infant neutrophil count of 1000 cells per cubic millimeter was associated with an 11% reduction in the risk of perinatal HIV infection. Maternal neutrophil count was associated with perinatal HIV infection after adjustment for cotrimoxazole treatment, CD4+ count, and infant sex and birth weight (P=0.05). These results suggest that pregnant women with low neutrophil counts may need more targeted, earlier interventions to prevent the intrauterine transmission of HIV to their infants.