Puberty and menstruation

A thyroid problem can cause puberty and the first menstrual period to start early or late. High or low levels of thyroid hormone can cause very light or very heavy periods. It can cause irregular periods. It can cause absent menstrual periods. This is called amenorrhea.

Reproduction

A thyroid problem may affect ovulation. This is the release of an egg from an ovary. A thyroid problem may stop ovulation from happening. The ovaries are at higher risk for cysts if the person has an underactive thyroid. Severe underactive thyroid can cause the breasts to make milk and prevent ovulation.

Pregnancy and postpartum

A thyroid problem in pregnancy can harm the baby. They may lead to ongoing thyroid problems in the parent after birth. An example of this is postpartum thyroiditis. A low amount of thyroid hormone can cause serious problems. These include pre-eclampsia, miscarriage, preterm birth, stillbirth, heart failure (rare), and bleeding after birth. A person with an overactive thyroid in pregnancy is at risk of morning sickness that is more severe, as well as an increased risk of miscarriage, stillbirth, high blood pressure and heart failure in both the birth parent and the fetus.

Menopause

A thyroid problem may cause early menopause. This means it happens before age 40 or in the early 40s. Some symptoms of overactive thyroid may seem like early menopause. These include lack of a menstrual period, hot flashes, inability to sleep (insomnia), and mood swings. Treating overactive thyroid may ease symptoms of early menopause. It may prevent menopause from happening too early.

Bone health

Overactive thyroid can affect the bones. Too much thyroid hormone can cause the bones to lose calcium. This is called osteoporosis.

Emotional and mental health

An untreated thyroid problem can cause emotional and mental health problems. It can cause depressed mood, fatigue, weight gain, reduced sexual desire, and trouble thinking.