A possible exception is rifampin , the antibiotic prescribed for tuberculosis .

可能的例外就是利福平，这种抗生素是专为治疗肺结核研制的。

Studies clearly show that rifampin decreases the effectiveness of birth control pills in preventing ovulation .

研究清楚显示，利福平会降低避孕药抑制排卵的效力。

Rifampin does lower pregnancy-protecting hormone levels induced by birth control pills , but whether the effect is large enough to increase pregnancy risk is unclear .

利福平确实会降低服用避孕药所产生的适合怀孕的荷尔蒙含量，但是这种反应是否大到可以影响怀孕机率的程度还不知晓。