There isn’t enough conclusive research to show that women with borderline hypothyroidism can avoid miscarriages or infertility through hormone supplementation, but it is still medically recommended due to the potential benefits and low risk of side effects. (8) In women who have overt (as opposed to borderline) hypothyroidism, it is more established that hypothyroidism can affect fertility rates and can increase the risk of miscarriages. Women who are hypothyroid may not produce enough luteinizing hormone (LH), which is involved in the mid-menstrual cycle surge of hormones that signal the ovaries to release an egg. Without this signal, ovulation may not occur, which will impede conception. In a study where approximately 24% of infertile women were diagnosed with hypothyroidism, researchers found that over 76% of these women could conceive within 6 months to 1 year after getting their hypothyroidism treated. (9)