To the Editor: We read with interest Giles and colleagues’ recent article, which examined the adoption of strategies to reduce perinatal transmission of HIV infection in Australia.1 They found that uptake of strategies to reduce perinatal HIV transmission had increased, with widespread use of antiretroviral therapy (ART) and breastfeeding avoidance. The authors also noted that caesarean birth was a strategy less commonly utilised by women with HIV infection. They made particular comment about the caesarean delivery rate for women known to have HIV infection in Western Australia. It was disappointing that the authors did not refer to our recent publication describing the low rate of perinatal HIV transmission in WA using an individualised delivery modality policy.2

In our consecutive series of 56 pregnancies between 1991 and 2005, 48 (86%) were managed by a multidisciplinary team, with 98% (47/48) of women receiving ART (one woman actively declined this intervention). Only one baby in the group who received care through the multidisciplinary team acquired perinatal HIV. This pregnancy occurred in 1991 in a woman with advanced disease who received zidovudine monotherapy, a situation not applicable today.

Elective caesarean delivery was based on either obstetric indications or a high HIV RNA level; 75% of women in our series had a vaginal delivery. The findings of our study were of particular note because 39% of mothers were Aboriginal, and predominantly from rural and remote regions of WA.

Although the patient numbers in our study were small, the current international evidence does not support mandatory caesarean delivery for women receiving ART with undetectable plasma HIV RNA.3 The risk of vertical transmission in this circumstance is low, and caesarean birth is associated with short- and long-term morbidity (most notably, placenta accreta). Recent series have shown a trend of increasing vaginal birth rates among women with well controlled HIV infection.4,5

When infection is well controlled, we believe that the mode of delivery should be individualised, and vaginal birth should be an option for women who desire this delivery method. It is disappointing that Giles and colleagues appear to imply that the low caesarean delivery rate in WA is a reflection of suboptimal HIV care processes, rather than evidence-based practice.

In reply: We were interested in Gilles and colleagues’ response to our analysis of the uptake of interventions to prevent perinatal HIV transmission in Australia.

As Gilles et al state, the reported rates of perinatal HIV transmission are low in Western Australia, where the choice of delivery modality is individualised. We agree that the additional benefit of elective caesarean section in women being treated with highly active antiretroviral therapy with an undetectable viral load is not known.

We also agree that elective caesarean section is associated with potential risks, and women should have a choice regarding mode of delivery. This choice should be informed by other obstetric factors, maternal viral load, and the clinical setting in which delivery takes place.

Geographic variation in such factors is likely, and will certainly contribute to differences across states in the uptake of preventive interventions. Ongoing national surveillance will help ensure that women with HIV infection and their children benefit as much as possible from evidence-based obstetric practices.