Antiretroviral (ARV) resistance mutations in HIV-1 may reduce the efficacy of prophylactic therapy to mother-to-child transmission and impact future treatment options. ARV resistance mutations and HIV-1 phylogenetic diversity in protease (PR) and reverse transcriptase (RT) genes were assessed among 77 pregnant women (35 naïve, 42 treated with ARV) from Goiânia/Goiás, central west Brazil. ARV mutations in PR/RT genes were analyzed against the Stanford Database, PR/RT HIV-1 subtypes were assigned by phylogenetic analysis and env/gag subtypes were identified by heteroduplex mobility analysis (HMA). Naïve patients had accessory mutations in the PR gene [A71T (1/6), L10V (2/6), L10I (3/6)] and in the RT gene [V118I (2/6), V179D (1/6), V106I (1/6), K101Q (1/6), H221Y (1/6)]. Seven patients (16.7%) under ARV presented drug resistance mutations, one of them to three ARV classes. Most isolates (67.5%) were subtype B, 11.7% subtype F1 and 3.9% subtype C. Recombinant B(PR)/F1(RT) viruses represented 10.4% while F1(PR)/B(RT) viruses made up 6.5%. HIV-1 envgag/PRRT genes were identified as 66.2% subtype B, 3.9% subtype C, 6.5% subtype F1 and approximately 25% B and F1 viruses. HIV-1 genetic diversity in envgag/PRRT genes indicates the spread and dissemination of BF1 recombinant viruses among a significant proportion of patients from central west Brazil. Moreover, discovery of HIV-1 secondary resistance among a considerable number of pregnant women under ARV therapy indicates the importance of genotypic testing during pregnancy for optimal prophylactic intervention. J. Med. Virol. 82:351-357, 2010. (c) 2010 Wiley-Liss, Inc.