Though it is the most common type of thyroid disorder, hyperthyroidism isn't the only problem a woman could have. Her levels could swing the other way in a condition called hypothyroidism.
With hypothyroidism, the thyroid gland doesn't produce enough T3 and T4 hormones, which can affect a person's metabolism in a completely different way than over-production. Some symptoms of the condition include weakness and fatigue, depression, brittle hair or fingernails and unintentional weight gain [source: PubMed Health].
The most common cause of low thyroid production is a condition called Hashimoto's disease, similar to Graves' disease in that it's an autoimmune disorder. With Hashimoto's disease, the body's immune system mistakenly attacks the thyroid itself, damaging the gland's cells and reducing the amount of hormone it can produce [source: NEMDIS].
With cases of hypothyroidism that are less severe, ovulation can occur normally, much like with hyperthyroidism. However, the condition has to be closely monitored and possibly treated if a woman becomes pregnant.
In addition, there is one type of hypothyroidism that is extremely dangerous both to women trying to get pregnant and those already carrying a child. Though rare, a condition known as myxedema coma can occur in women with hypothyroidism.
Myxedema coma is a potentially lethal condition where thyroid hormone levels drop an extreme amount. It is often accompanied by a drop in body temperature, low blood pressure, low blood sugar levels, a decrease in breathing and potential unresponsiveness. Complications from myxedema coma can include infertility, but also miscarriage in a woman already pregnant [source: NEMDIS].
As with any condition, consult your regular medical professional if you have concerns about a potential thyroid problem. The right testing can diagnose thyroid functioning, and your doctor can recommend what treatments are available.