Timing of vertical transmission

Exact timing when vertical transmission occurs varies from case to case. It can occur in utero as early as 15-20 weeks as aborted fetuses have been shown to be infected with HIV. In addition some workers have described HIV dysmorphism in some cases characterized by craniofacial dysmorphism and congenital heart disease. But the fact that most of the HIV infected babies are normal at birth suggest that the infection occurs most commonly in last trimester, during labor and via breast milk postnatally. This is also evident by the fact that interventions to decrease vertical transmission are able to block it by 50-65%.

The relative frequency of timing at which transmission occurs is as follows: Of the 30% of babies who get infected vertically, 2% get infected early in gestation and 3% late in gestation mainly in last month of gestation. 15% get infected during labor, 5% get infected in early post partum period and 5% in late post-partum period. Most of the interventions target the late prenatal period, labor and postnatal period to block transmission.  

Prevention of parent to child transmission (PTCT)

Parent to child transmission is a more appropriate word than mother to child transmission as mother usually gets infected from her husband. PTCT blockage involves four strategies: -



Phases of PTCT prevention

PTCT prevention involves 5 phases: -

Phase I: This phase involves giving information on voluntary counseling and testing, infant feeding, option of MTP, family planning measures, problems of orphans etc. to mother who is HIV positive. This will go a long way in preventing pregnancies or decrease exposure of babies to maternal HIV.

Phase II: This phase involves giving prophylaxis to mother and child which includes anti-retroviral drugs to mother and baby and use of safe delivery practices like elective LSCS and non-traumatic vaginal delivery.

Phase III: This phase involves issues related to replacement feeds Vs breast-feeds.

Phase alpha: This phase involves primary prevention of HIV in mothers and society. This includes HIV education, avoiding high-risk behaviors, treatment of STDs, imparting life skills etc.

Phase omega: This phase includes care and support of already HIV infected mothers and babies, social support and economical support etc.