Treatment change in pregnancy is a significant risk factor for detectable HIV-1 RNA in plasma at end of pregnancy.

PURPOSE: To investigate the risk factors for an HIV-1 RNA plasma viral load above 400 copies/mL in the third trimester of pregnancy.

METHODS: Data from a large national study were used. The possible determinants were assessed in univariate analyses and in a multivariate logistic regression model in order to adjust for possible confounders.

RESULTS: Among 662 pregnancies followed between 2001 and 2008, 131 (19.8%) had an HIV-1 plasma copy number above 400/mL at the third trimester of pregnancy. In the multivariate analysis, the variables significantly associated with this occurrence were earlier calendar year (adjusted odds ratio [AOR] per additional calendar year, 0.70; 95% CI, 0.63-0.77; P<.001), lower CD4 count at enrollment (AOR per 100 cells lower, 1.18; 95% CI, 1.09-1.27; P<.001), HIV-1 RNA levels above 400 copies per mL at enrollment (AOR, 2.23; 95% CI, 1.50-3.33; P<.001), and treatment modification during pregnancy (AOR, 1.66; 95% CI, 1.07-2.57; P=.024).

CONCLUSIONS: Treatment changes in pregnancy significantly increase the risk of an incomplete viral suppression at the end of pregnancy. In HIV-infected women of childbearing age, proper preconception care, which includes the preferential prescription of regimens with the best safety profile in pregnancy, is likely to prevent an incomplete viral suppression at the end of pregnancy.