Definition of Amenorrhea - primary:

Amenorrhea is the absence of menstruation. Menstruation is a woman's monthly period.

Primary amenorrhea is when a girl has not yet started her monthly periods, and she:

• Has gone through other normal changes that occur during puberty
• Is older than 15

See also:

• Menstruation - absent
• Secondary amenorrhea

Causes, incidence, and risk factors:

Most girls begin menstruating between ages 9 and 18, with an average around 12 years old. Primary amenorrhea typically occurs when a girl is older than 15, if she has undergone other normal changes that occur during puberty. Primary amenorrhea may occur with or without other signs of puberty.

Being born with poorly formed genital or pelvic organs (missing uterus or vagina, vaginal septum, cervical stenosis, or imperforate hymen) can lead to primary amenorrhea.

Hormones play a big role in a woman's menstrual cycle. Hormone problems can occur when:

• Changes occur to the parts of the brain where hormones that help manage the menstrual cycle are produced
• The ovaries are not working correctly

These problems may be due to:

• Genetic defects
• Infections that occur in the womb or after birth
• Other birth defects
• Tumors

In many cases, the cause of primary amenorrhea is not known.

Conditions associated with primary amenorrhea include:

• Adrenogenital syndrome
• Anorexia
• Chromosomal abnormalities such as Turner syndrome or Sawyer syndrome
• Congenital heart disease (cyanotic)
• Congenital adrenal hyperplasia
• Craniopharyngioma
• Chronic (long-term) illnesses
• Cushing's disease
• Cystic fibrosis
• Gonadal dysgenesis
• Hypothyroidism and hyperthyroidism
• Hypogonadotropic hypogonadism
• Hyperprolactinemia
• Obesity
• Prader-Willi syndrome
• Polycystic ovarian disease
• Testicular feminization
• True hermaphroditism
• Tumors of the pituitary or adrenal glands
• Tumors of the ovaries