 Born in Puerto Tejada, Cauca, Obregón began representing Colombia as a teenager and won her first international medals (silvers over 100 metres and 200 metres) at the 2002 South American Youth Championships.She was fifth in the 200 m at the South American Junior Athletics Championships the following year and also competed on the world stage at the 2003 World Youth Championships in Athletics, where she came seventh in the 200 m final.She stepped up an age category for the South American Under-23 Athletics Championships and won the 200 m gold medal.