The determination of accurate masses from the study of binary orbits requires a combination of complementary observing techniques. In this respect, of particular interest is the solution of astrometric orbits for long-period spectroscopic binaries by applying interferometric techniques. Results of a high-resolution spectroscopic monitoring of low-mass Pre-Main Sequence (PMS) spectroscopic binary (SB) systems in nearby star formation regions (SFR) of the Southern Hemisphere, conducted at ESO with FEROS, aiming to identify SB systems with long-period orbits, suitable for follow-up observations with the VLTI are presented. The ultimate aim is the determination of dynamical masses for a representative sample of young low-mass stars of different masses and ages to provide strong observational constraints for current PMS theoretical models.