The growing number of young Hispanic mothers is the primary cause for an uptick in Montgomery County's teen pregnancies, according to state statistics presented yesterday to county leaders. In the county, which has one of the lowest overall birthrates in the United States, the birthrate increased 16 percent from 2002 to 2005 among all women 15 to 19, according to a report by county staff. In the same period, births for women in that age group dropped nationally and statewide. Births among Hispanic women 18 to 19, which have particularly driven the growth in teen pregnancies in Montgomery, have increased...