Very low rate of MTCT in women on HAART in UK and Ireland who achieve viral suppression

A poster from Claire Townsend and coworkers from the Institute of Child Health, St Thomas Hospital and St Marys Hospital looked at HIV mother to child transmission (MTCT) rates among women and infants in the UK and Ireland 2000 to 2006.

In recent years, transmission rates have declined to 1 to 2% in Western Europe. With the success of HAART in reducing transmission, women are increasingly opting for vaginal delivery, instead of elective caesarean section.

In the BHIVA guidelines AZT monotherapy with elective caesarean section is also offered as an option for some women who do not need HAART for their own health and who have very low viral loads.

In this analysis, HIV status was available for 5136/6127 (86.8%) infants. The authors reported that the overall MTCT rate was 1.1% (61/5316, 95% CI 0.9% – 1.5%), and 0.8% (40/5027, 95%CI 0.6 -1.1%) in infants whose mothers received ART for at least 14 days.

They found no significant difference in MTCT rates between women receiving HAART who had an elective caesarean section (17/2337, 0.7%, 95% CI 0.4 to 1.2%) or a planned vaginal delivery (4/565, 0.7%, 95%CI 0.2 to 1.8%). Nor was there a difference for mothers receiving prophylactic AZT monotherapy who had an elective caesarean section (0 /467, 0%, upper 95%CI 0.8%; p=0.094).

In these three groups, the numbers of women with viral load <50 copies/mL were 59% 1341/2276 (59%), 508/634 (80%) and 105/447 (23%), respectively. They found only three transmissions reported among 2202 infants born to women on HAART with viral load <50 copies/mL (0.1%, 95%CI 0 to 0.4%): 2 were born by elective caesarean section (MTCT rate 0.2%, 2/1180) and 1 by planned vaginal delivery (MTCT rate 0.2%, 1/419).

Of the three HIV-positive infants, two had positive PCR tests at births, suggesting in utero transmission and the other was negative at birth suggesting intrapartum transmission.

The authors wrote: There was no difference in MTCT rates according to the management strategies outlined in the BHIVA Guidelines: HAART with elective caesarean section or planned vaginal delivery, and zidovudine monotherapy with elective caesarean section. The risk of MTCT in appropriately managed pregnancies in the United Kingdom and Ireland is very low.

Comment

These data are very reassuring; with good management focusing on maternal health and choice, there is little risk of transmission to her child for an HIV-positive mother delivering in the UK today. The 1/1000 transmission rate for women receiving HAART with an undetectable viral load (<50 copies/mL) across both modes of delivery is the lowest reported and represents a significant advance in the information available to women planning a family or already pregnant.

The similarly low transmission rate seen in selected women with very low viral load who chose to receive AZT monotherapy and deliver by elective caesarean section is important too, as it confirms that this remains an option.

Townsend C, Cortina-Borja M, C Peckham C et al. Very low risk of MTCT in women on HAART who achieve viral suppression: The UK and Ireland, 2000 to 2006. 15th CROI. February 2008, Boston. Poster abstract 653