Pregnant women who are barred from jobs or housing because they are carrying a child can now file discrimination complaints with the state under a bill signed into law by Gov. George Deukmejian. The measure authorizes the state Department of Fair Employment and Housing to accept complaints of discrimination against pregnant women. Pregnant women in California file about 600 complaints of alleged discrimination each year, said Lisa Ramer, an aide to state Sen. Nicholas C. Petris, the Oakland Democrat who carried the bill through the Legislature. The new law does not take effect until Jan. 1, 1991, but the fair employment and housing department agreed last December to implement the measure and hear complaints from pregnant woman.