- Due to the unknown effects of MDX-CTLA-4 on the fetus or nursing infant, pregnant or nursing women should not be included; women should be either: post-menopausal for at least 1 year; surgically incapable of bearing children; or utilizing an intrauterine device, and/or spermicide and barrier, for contraception; during the study, use of oral contraception alone is not acceptable; women of childbearing potential must have a negative serum beta-HCG pregnancy test conducted during screening, and a negative urinary beta-HCG pregnancy test conducted within 24 hours prior to treatment; due to the unknown effects of MDX-CTLA-4 on the fetus, men should not father children during the study