dose therapy study male starting method contraception agree adequate use method contraception barrier use effective childbearing potential willing discontinuation females effective contraception use agree sterile patients surgically fertile study dose highly effective contraception study use male female methods period potential reproductive contraception potential effective use agree female study method male contraception use adequate method agree study male duration willing agrees fcbp lenalidomide pregnancy effective method days agree commit begin starts female childbearing potential male contraception partners use effective patients agree contraceptive use study agree potential effective methods method dose childbearing avoidance producing measures child agree male contraception potential female use