Can birth control pills cause hypothyroidism?

Don't Cause: Ocp's don't cause hypothyroidism. They can alter a binding protein called TBG which can change doses of thyroid replacement therapy.

NO: Birth control pills do cause some changes in the results of thyroid tests for women taking birth control pills, but they do not cause hypothyroidism.

Oral estrogen pills: of any kind cause an increase in thyroid binding globulin as part of the first pass effect in the liver. This increases the binding and decreases the availability of free thyroid hormone. This doesn't "cause" hypothyroidism but does effect the thyroid. Women with hypothyroidism that are on OC's might require a higher dose of thyroid. I often recommend the Nuvaring in those patients to avoid this.