If you have an underactive thyroid (hypothyroidism), your thyroid gland doesn't produce enough of certain important hormones. For women, there's sometimes a link between hypothyroidism and infertility. Low levels of thyroid hormone can interfere with the release of an egg from your ovary (ovulation), which impairs fertility. In addition, some of the underlying causes of hypothyroidism — such as certain autoimmune or pituitary disorders — may impair fertility. For women, treating hypothyroidism is an important part of any effort to correct infertility. If infertility remains after hypothyroidism has been corrected, other interventions to treat infertility may be needed. If you have hypothyroidism and hope to become pregnant, work with your doctor to make sure your hypothyroidism is under control. Seek additional help from an infertility specialist if needed.