A polyvalent vaccine for control of fertility is disclosed, the vaccine having a multiplicity of determinant antigens in the reproductive system of mammals, the antigens being linked to at least one carrier. The precise manner of linkage can differ, and preferably more than one carrier is present thereby increasing antibody response particularly in those subjects who are poor responders when a single carrier only is used. The new vaccine thus has a multi-valent capability against the reproductive system and also preferably the capability of producing immunoprophylactic benefit against more than one health hazard.