Prevention of Mother-to-child HIV transmission Flashcards
When does HIV transmission from mother-to-child mainly take place?
in the 2 months preceding birth; highest at birth
Wihtout intervention, how high can mother-to-child transmission be?
upto 45% by the end of breastfeeding
What is the route by which transmission takes place pre-partum?
transplacentally and transmiamniotically
What are the routes of transmission intra-partum?
transplacental; birth canal
What is the most important factor determining risk of HIV transmission?
viral load
Why do pre-term labour and low birth wt increase the risk of transmission?
they are signs of hte materno-fetal unit not functioning correctly
What was the effect of giving AZT to mothers and babies to reduce transmission?
reduced transmission rate by 2/3rds
How does elective C/S change the risk of transmission compared with SVD when using AZT?
80% reduction in transmission with ECS both with and without ZDV
What did the women, infant transmission study look at?
the difference in transmission rates between no ART; ZDV; combo and HAART
What were the results of the women; infant transmission study?
HAART was most effective at reducing tranmission; then combo; then ZDV then no ART
What is the overall rate of MTCT in UK between 200-2006?
1.1% overall
What is the impact of ECS vs SVD if the patient is on HAART and VL is undetectable?
no difference in transmission rate
When should cART be started during pregnnacy according to a retrospective London study?
before 24 weeks GA
what is the overall risk of transmission when duration of ART is 9 weeks?
1%
When does MTCT plateau in terms of ART duration?
aroudn 13 weeks
What is the asbolute risk of MTCT with breastfeeding?
15-20%
What was the overall HIV-free survival bewteen breast and formula
in a RCT in 2000?
58% with breast and 70% with formula
What are the benefits of using ARt whilst breastfeeding?
MTCT rates <1%; improved maternal health; benefits of breastfeeding
What are hte risks of using ART whilst breastfeeding?
infant exposure to drug; risk of HIV resistance if infant ebcomes HIV+; possible ongoing transmission risk
What are the WHO guidelines for breastfeeding for HIV+ mothers?
in settings where lifelong ARt is provided and supported, a mother should breastfeed for at least 12 months and may continue upto 24 hours
What is the BHIVA recommendation for breastfeeding?
not recommended
How is HIV related to preterm birth?
HIV associated immune deficiency is assoacited with PTB, but also HIV is a risk even with immune restoration
What is the impact of mixed breastfeeding compared with exclusive?
mixed breastfeeding is a much higher risk
Which type of ART is the worst for increasing the risk of PTB?
protease inhibitors
What is the effect of ART on PTB in mothers with CD4>200?
50% increase in risk compared with no ART or AZT monotherapy in a Swiss study
What is the impact on PTB depending on when ART is started?
risk of PTB is higher if started during pregnancy- especially with PI
What happens to the Th1/Th2 cytokine balance in pregnancy?
shifts towards Th2
What happens to the Th1/Th2 cytokine balance in untreated HIV?
shifts twards Th2
What happens to the Th1/Th2 cytokine balance with treated HIV?
shifts back to Th1
What type of cytokine balance is PTB assocaited with?
Th1
What is a proposed mechanism for the increased risk of PTD with PIs?
PIs may reduce progesterone levels in pregnancy leading ot fetal growth restriction
What did the NSHPC study find when looking at ART and PTD?
increased rate of PTD with cART (14%) vs mono/dual therapy (10%)
What was the risk of PTD with women who conceived on PI based regimens vs NNRTI?
higher with PI
What is the risk of PTD if on ART at conception vs starting in pregnancy?
higher if on for conception
What is the effect of CD4 count on PTD?
PTD risk is higher in those with lower CD4 coutns
Which studies support the hypothesis that ZDV-based therapies are associated with a lower risk of PTD?
PROMISE; Mma Bana and NSHPC
What is a possible reason for a resurgance in the risk of pre-eclampsia in the cART era?
restoration of immune function- a form of IRIS?
What might influence the data on the timing of ART initiation- pre-conception vs in pregnancy?
ART was only prescribed outside of pregnancy until recently to women with immune deficiency and/or low CD4 so pre-conception ART risk may be a reflection of the causes of the HIV disease
What finding in the HIV PTB study supports the cytokine shift as a mechnism for ART increasing risk of PTD?
women with PTD had much lower IL10 and IL4 concentrations compared with those who delivered to term, and PIs decreased IL10 and IL4 concs
What is the effect of HIV infection upon vaginal flora?
HIV infection is assocaited with a reduction in lactobacillus species; increased anaerobes- Gardnerella and Prevotella— much lower levels of protective vaginal flora in HIV infected mothers
What was the relationship bewteen vaginal flora and PTB?
women with PTB had much higher levels of anaerobes
What is the impact of tenofovir on vaginal flora?
women exposed have a higher % of gardnerella
Where do 85% of HIV-infected pregnant women live?
Africa
When should ART be started in pregnancy if viral load >100,000 or CD4 <200 according to BHIVA?
first trimester
When should ART be started in pregnancy if VL <100000?
second trimester
When should planed vaginal delivery be supported in women with HIV?
when have a VL <50 at 36 weeks
When should CS be carried out to prevent vertical transmission?
between 38 and 39 weeks
How often should a HIV positive women who chooses to breasfeed be monitored in clinic?
her and baby should be reviewd monthly for HIV RNA during and for 2 months after breasfeeding
Why should ART be started as soon as possible?
in both UK and a French cohort, vertical transmission was significantly assocaited with starting treatment later in pregnancy
