NEW YORK (AP) -- The New York Civil Liberties Union has filed a federal discrimination complaint against a Catholic school, charging that it unjustly fired an unmarried teacher for being pregnant."I don't understand how a religion that prides itself on forgiving and on valuing life could terminate me because I'm pregnant and choosing to have this baby," Michelle McCusker said Monday at a news conference to announce the suit.The 26-year-old preschool teacher was fired last month from St. Rose of Lima in Queens, according to published reports. (Watch what was in her termination letter -- 1:36) The Diocese of Brooklyn also was named in the Equal Employment Opportunity Commission complaint."This is a difficult situation for every person involved, but the school had no choice but to follow the principles contained in the teachers' personnel handbook," diocese spokesman Frank DeRosa said in a news release.The handbook says that each teacher must "convey the teachings of the Catholic faith by his or her words and actions."Lawyers at the NYCLU, which filed the suit on McCusker's behalf, argued that administrators enforced the policy in a way that disproportionately affects women."The school used her pregnancy as a marker," attorney Cassandra Stubbs said. "How do they determine if male employees engage in premarital sex?"It's not the first time the NYCLU has argued such a case. In 2003, the unmarried director of an after-school program run by a Catholic charity in Buffalo was demoted when she became pregnant. The equal employment commission found that the charity had violated federal anti-discrimination laws, the NYCLU said.That charity agreed to ban discrimination based on marital status or pregnancy.Copyright 2005 The Associated Press. All rights reserved.This material may not be published, broadcast, rewritten, or redistributed.