Many women have thyroid dysfunction. Thyroid hormone and Thyroid Stimulating Hormone (TSH) play an important role in milk production. The body’s thyroid requirement changes during pregnancy and women who are on thyroid replacement may have their dose slightly increased during the pregnancy. After delivery, the dose is often decreased to the original pre-pregnancy dose. Both over-treated and under-treated thyroid dysfunction can affect milk production. If you are having problems with low milk production, speak with your doctor about checking your thyroid levels.