Rifampin is a drug used in the treatment of tuberculosis. In the literature, there are reports of seven patients who became pregnant while taking a combination of rifampin and oral contraceptives. We report an eighth case involving a woman who became pregnant twice on this drug combination.
(JAMA 236:1382, 1976)
Skolnick JL, Stoler BS, Katz DB, Anderson WH. Rifampin, Oral Contraceptives, and Pregnancy. JAMA. 1976;236(12):1382. doi:10.1001/jama.1976.03270130044027