 To help spread anti-fascist propaganda among the women of Croatia, she
helped to found the first women’s newspaper, "Woman in Struggle" (Žena u borbi), in partisan-controlled Croatia in March 1942.Later that year, she was the only woman delegate to the Anti-Fascist Council for the National Liberation of Yugoslavia () in November and Pejnović was elected President of the Antifascist Women’s Front ("Antifašistički front žena") shortly afterwards.She was elected to the Central Committee of the Communist Party of Croatia in 1948 and repeatedly served in the Parliament of the People’s Republic of Croatia and twice in the Federal Assembly.