The anticonvulsant/mood stabilizer medication carbamazepine…

The anticonvulsant/mood stabilizer medication carbamazepine is considered a STRONG inducer of the hepatic enzyme CYP3A4. You would like to prescribe the combined oral contraceptive ethinyl estradiol and desogestrel to a patient. Both ethinyl estradiol and desogestrel are substrates for CYP3A4, which is responsible for phase I metabolism. What outcome would be expected if a patient was administered these medications together?