Sulphadoxine-pyrimethamine ( 1,500 / 75 mg ) plus azithromycin ( 1 g twice daily for 2 days ) ( SPAZ ) monthly from second trimester ( intervention ) was compared against sulphadoxine-pyrimethamine and chloroquine ( 450 to 600 mg , daily for three days ) ( SPCQ ) given once , followed by SPCQ placebo ( control ) .