Spikes in viral load after initial viral suppression during pregnancy are mostly due to suboptimal treatment adherence rather than resistance mutations acquired before conception, a South African case-control study published in Clinical Infectious Diseases showed.
All 167 participants initially achieved viral suppression during pregnancy, but viral load subsequently rose in 80 of the women, while 87 controls remained suppressed. All were followed for up to one year after giving birth.
Among the 80 women who experienced an eventual viral load increase, pre-treatment drug resistance mutations had been found in just 10%. Among the women who remained suppressed, 5% had such mutations.
By contrast, recent HIV medication usage was detected in only 19% of cases in which a woman's viral load was elevated, compared to 94% of women who remained virologically suppressed. The method of detection used in the study was only capable of detecting medications taken within two to four days before a study visit; thus, long-term adherence was unknown.
Among women who experienced an elevated viral load, the most common drug resistance mutations discovered were for non-nucleoside reverse transcriptase inhibitors -- particularly the K103N and V106M mutations, which show the limitation of efavirenz (Sustiva, Stocrin) as first-line therapy, study authors wrote. They suggested dolutegravir (Tivicay, DTG) as a better alternative for the study population.