Human Immunodeficiency Virus Viral Load Rebound Near Delivery in Previously Suppressed, Combination Antiretroviral Therapy-Treated Pregnant Women.

Objective: To assess the stability of human immunodeficiency virus (HIV) viral load suppression within 1 month before birth in pregnant women receiving antenatal combination antiretroviral therapy (CART).

Methods: This is a retrospective cohort study of a Canadian provincial perinatal HIV database from 1997 to 2015. Inclusion criteria were live birth and CART received for at least 4 weeks. Viral load rebound, defined as viral load greater than 50 copies/mL (or greater than 400 copies/mL for 1997-1998) and measured within 1 month before delivery, was identified in women who had at least one previous undetectable viral load during pregnancy. Logistic regressions were conducted to identify the risk factors for viral load rebound.

Results: Among the 470 women in the database, 318 met inclusion criteria. Viral load rebound was experienced by 19 women (6.0%, 95% CI 3.7-9.3%) with a mean log10 viral load near delivery of 2.71 copies/mL (=513 copies/mL). Six (32%) had a viral load above 1,000 copies/mL. The rebound was detected within 1 day before delivery in 50% of the women. Aboriginal ethnicity, cocaine use, and hepatitis C virus polymerase chain reaction positivity were significantly associated with viral load rebound. There were no HIV vertical transmissions.

Conclusion: Even women attending for HIV care and achieving viral suppression in pregnancy can experience viral load rebound predelivery.