TRENTON (AP)nA group of deer that were injected with a birth control vaccine are still getting pregnant, leading wildlife officials to look for new options to cut down on the state's deer population. Last year, 52 female deer in Mercer County were injected with a drug called SpayVac, a contraceptive that was expected to keep them from reproducing for years and could be administered with one shot. But a few months ago, wildlife officials started to notice fawns in the Princeton Township area, indicating the birth control wasn't working. ``It looked very promising, but now it's going to sit on the shelf and that's unfortunate,'' Anthony DiNicola, president of White Buffalo Inc., the company that was administering the vaccine along with the state Division of Fish and Wildlife, told The Sunday Star-Ledger of Newark. DiNicola said the company was able to revaccinate 39 of the deer last month with another contraceptive called GnRH, which is expected to last two to four years. It also prevents female deer from going into heat, meaning they would be less likely to be chased by male deer and run in front of oncoming cars. New Jersey has an estimated 200,000 deer that are often hit by cars and wreak havoc on crops. Wildlife officials have been looking for ways to control the deer population and in the nation's most densely populated state, hunting isn't always a feasible option.