ART at least 13 weeks before giving birth provides the greatest benefits in prevention
of mother-to-child transmission (PMTCT), Carla J Chibwesha and colleagues
reported in a retrospective cohort analysis of pregnant HIV-infected women
attending public antenatal care clinics in Lusaka, Zambia
published in the advance online edition of the Journal of Acquired Immune Deficiency Syndromes.
who got ART for a month or less before giving birth had more than a five-fold
increased risk of transmitting HIV to their infants compared to women on ART
for at least 13 weeks (95% CI: 2.5-11).
The findings underline the importance of HIV counselling and testing at the earliest opportunity after a woman becomes pregnat, and the importance of minimising the delay between testing positive and starting antiretroviral treatment.
90% of the more than 1,000 daily new paediatric HIV infections are in
sub-Saharan Africa. Maternal ART can reduce
MTCT to 2-5% or lower.
the World Health Organization (WHO) guidelines now recommend that all pregnant
women with CD4 cell counts under 350 cells/mm3 should start ART, women
in resource-poor settings are usually restricted to four or fewer antenatal
visits, which means that HIV testing may take place late in pregnancy, delaying
the start of treatment until the third trimester.
viral load for women on ART during pregnancy and breastfeeding determines the
risk of transmission, so suppression of viral load is the primary goal of ART
for PMTCT. Viral load monitoring can help guide clinical management during
pregnancy. However, for financial and logistic reasons, this option is rarely
available in resource-poor settings.
guidelines recommend starting ART as soon as a woman is eligible, the optimal
time on antenatal ART is unclear.
authors undertook a retrospective cohort analysis to look at the effect of the
duration of antenatal ART on perinatal HIV transmission. Women who began ART
before or during pregnancy and whose infants had had an HIV polymerase chain
reaction (PCR) test between three and 12 weeks of life were included.
HIV testing in antenatal clinics has resulted in a testing rate of over 90% for
women. CD4 cell counts are routinely done for ART eligibility. Women get ART in
treatment centres or in antenatal clinics with integrated ART services.
medical information on mothers and newborns up to six weeks of age has been
collected in the public antenatal clinics since 2006 through an electronic
medical record system.
of ART treatment was classified as: four weeks or less; 5-8 weeks; 9-12 weeks,
or 13 weeks or more.
January 2007 to March 2010 of the 1813 HIV-infected pregnant included in the
analysis the overall mother-to-child transmission rate was a relatively low
3.3% (59 of 1,813) (95% CI: 2.5-4.2%) between three and 12 weeks of life.
mean age was 29 years. Over 90% of the women were married with more than 85%
pregnant previously. At the first
antenatal visit the mean gestational age was 21 weeks (standard deviation ± six
weeks).The median CD4 cell count was 231 cells/mm3(IQR: 164-329
cells/mm3) and median length of time on ART before giving birth was
13 weeks (IQR: 8-19 weeks).
of time on treatment before delivery was the most important predictor of
in a previous study a positive syphilis test during pregnancy was found to be
an independent risk factor for perinatal transmission (AOR 3.8; 95% CI:
generalised additive model suggested limited protective benefits beyond 13
weeks on ART.
exploratory analysis of women on ART for less than 13 weeks showed that for
each additional week on ART before giving birth the risks of perinatal
transmission were reduced by 14% (OR: 0.86; 95% CI: 0.77-0.96).
women, the authors note, present for antenatal care in the second trimester
allowing sufficient time to start ART. A lack of timely identification of
HIV-infected pregnant women and subsequent linking to services results in poor
standards of care and preventable perinatal HIV infections.
findings, the authors note, underline the critical importance of getting
pregnant women into antenatal care early and for providers to determine ART
eligibility and start treatment promptly.
authors suggest key components for programme success include: support of routine HIV counselling and
testing; improved clinical and laboratory services including point of care CD4
cell counts; integration of ART services into antenatal clinic settings and
credentialing nurses and midwives to prescribe ART (task shifting).
antenatal care that promotes the prevention, screening and treating of
preventable conditions including sexually transmitted infections and anaemia
may improve women’s health and decrease perinatal HIV transmission, they add.
of the study include a large sample size and robust electronic medical record
in most resource-poor settings routine ultrasound to determine age of the
foetus and plasma viral load data were not available so limiting the findings.
the absence of viral load monitoring to guide HIV management the authors
recommend pregnant women with CD4 cell counts under 350 cells/mm3 start
ART at least four weeks but preferably 13 weeks before delivery to ensure the
greatest chance of preventing vertical transmission.