Oral contraceptives
Obesity is associated with infertility in women by various mechanisms89, which seems to be (totally or partially) reversible after bariatric surgery 90. As reproductive-aged women are advised to avoid pregnancy twelve to twenty-four months after bariatric surgery, contraceptives are recommended 91–93. An anticipated reduction in absorption area, residence time and enterohepatic circulation after bariatric surgery may potentially decrease the reliability of oral contraceptives. There is however limited information on the use of oral contraceptives after bariatric surgery. Victor et al. showed that norethisterone and levonorgestrel levels were lower after jejunoileal bypass at 1-8 hours after ingestion even though at 24 hours, there was no difference 94. Furthermore a reduced effect of oral contraceptives after biliopancreatic bypass was described95. Two of the nine patients who used oral contraceptives postoperatively were unexpectedly pregnant. These two patients suffered from chronic diarrhea. No unexpected pregnancies were reported among users of non-oral contraceptives 95. Ciangura et al. showed reduced norgestrel levels six months after RYGB, however, these values were considered sufficiently high for a contraceptive effect 96.
In conclusion, the absorption of oral contraceptives may be reduced, particularly in the event of chronic diarrhea following restrictive and malabsorptive bariatric surgery. Oral contraceptives should be discouraged or alternative contraception should be used. Of note, Damhof et al. showed that 16% of the women undergoing bariatric surgery are using potentially unsafe contraception postoperatively warranting the attention of the health care professional for this problem97.