factors affecting HIV transmission from mother to child
Last edited 03/2018
factors affecting mother-to-child transmission of HIV-1
Transmission from mother-to-child of HIV is affected by a number of factors which can be divided into:
- viral
- viral load - transmission is increased in the presence of high levels of maternal viraemia
- viral genotype and phenotype
- viral resistance
- maternal
- maternal immunological status
- transmission is more likely with decreased maternal immune status, reflected by low CD4+ counts, low CD4+ percentages or high CD4+/CD8 ratios
- maternal nutritional status
- serum vitamin A levels in HIV-1 positive mothers have been correlated with the risk of transmission. The mean vitamin A level in those mothers who transmitted virus to their children was significantly lower than in those who did not transmit
- maternal clinical status
- behavioural factors
- cigarette smoking, maternal hard drug use, unprotected sexual intercourse during pregnancy have been associated with an increased rate of transmission from mother to child
- antiretroviral treatment
- obstetrical
- prolonged rupture of membranes (> 4 hours)
- mode of delivery - delivery by caesarean section has been shown to be protective in some prospective follow-up studies
- intrapartum haemorrhage
- obstetrical procedures
- invasive fetal monitoring
- fetal
- prematurity
- genetic
- multiple pregnancy
- infant
- breastfeeding
- is responsible for a high proportion of mother-to-child transmission in developing countries
- gastrointestinal tract factors
- decreased acidity, decreased mucus, lower IgA activity and thinned mucosa in the newborn gastro-intestinal tract, may facilitate transmission following ingestion of virus in utero or at birth
- immature immune system
- newborn immune system may also be deficient in macrophage and T cell immune response, increasing the susceptibility to infection (1).
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