Dolutegravir/Lamivudine in Treatment-Naïve Pregnant Women

Primary endpoints:

* Proportion of pregnant women who achieve an HIV-1 plasma viral load \<200 copies/mL at delivery after starting DTG+3TC (Intention-to-Treat Exposed analysis). * Proportion of children born without HIV infection at 6 weeks \& 6 months of age, defined by the negative result of negative virological tests (PCR) performed at birth (delivery visit and up to 72 hours after delivery), at 6 weeks, and at 6 months

Secondary endpoints:

* Frequency of grade 2 or higher maternal adverse events, by type and severity, from baseline to 6 months postpartum. * Frequency of spontaneous abortion, preterm delivery, congenital malformations at birth or identified and reported during the first 6 month of life, or intrauterine fetal death. * Proportion of pregnant women with plasma viral load below 50 copies/mL at delivery. * Average total weight gain and BMI during pregnancy, compared with recommendations based on pre-pregnancy BMI. * Changes in CD4 lymphocyte count and CD4/CD8 ratio between baseline and delivery visit values. * Frequency and type of mutations according to the International AIDS Society (IAS-USA drug resistance mutations, 2025) mutation guidelines panel at the baseline visit and in case of virological failure at any time during the study. * Proportion of HIV infection among breastfed children. * Frequency of grade 2 or higher maternal adverse events, by type and severity, between the two arms. Frequency of pregnant women with plasma viral load \<200 copies/mL in the two arms at delivery visit.

Exploratory endpoints:

* Difference in the proportion of pregnant women who achieve an HIV-1 plasma viral load of less than 50 copies/mL at delivery between the DTG+3TC and DTG+TDF/XTC or DTG+TAF/FTC groups, to explore the non-inferiority of the dual regimen. * Proportion of participants requiring a change in antiretroviral regimen (due to lack of efficacy, adverse events, medical decision, or other reasons) before delivery.

Patient Population: HIV-1-infected Pregnant Women aged \>16 years (\>15 years for Brazil's sites) who are naïve to antiretroviral therapy Study design: Phase IV. Randomized, non-comparative, open-label, multicenter study.

Regimens: Dolutegravir 50 mg /lamivudine 300 mg QD FDC. Dolutegravir 50 mg QD plus tenofovir 300 mg/emtricitabine 200mg or plus tenofovir 300 mg/ lamivudine 300 mg or tenofovir alafenamide 25 mg/emtricitabine 200 mg.