Reasons for a Missed Period and Not Pregnant

It is common for women to skip a menstrual period occasionally. This condition is known as amenorrhea. Women often find it stressful when they miss a menstrual cycle and experience anxiety waiting for their cycle to return to normal. According to the MayoClinic.com, missing a period is rarely the result of a serious medical condition. However, it is important to visit a doctor or health care provider to seek out and treat the underlying problem.

A woman is holding a pregnancy test in the air. (Image: michaeljung/iStock/Getty Images)

Stress

Mental stress can temporarily cause the malfunctioning of the hypothalamus. The hypothalamus is responsible for the hormones needed during the menstrual cycle. As a result, both ovulation and menstruation can temporarily stop. Menstruation should return to normal once the stress decreases, according to the MayoClinic.com.

Polycystic Ovary Syndrome

A common cause of amenorrhea is a condition known as polycystic ovary syndrome. The American Congress of Obstetricians and Gynecologists explains that polycystic ovary syndrome occurs when the body produces excessively high levels of the hormones estrogen and androgen, rather than the fluctuating levels of estrogen and progesterone needed for ovulation. When ovulation fails to occur, the fluid-filled sacs begin to form on and inside the ovaries. PCOS symptoms include absent or abnormally heavy menstrual cycles, acne, obesity, infertility and excessive facial hair.

Contraceptives

Women taking birth control pills may not have periods. Even after a woman has stopped contraception, it may take up to six month for the regular cycle to resume. Injected and implanted contraception as well as intrauterine devices may also cause amenorrhea.

Pituitary Tumors

The pituitary gland is a pea-sized gland in the brain responsible for production of certain types of hormones. A noncancerous pituitary tumor may cause an overproduction of the hormone prolactin which can interfere with regulating menstruation. Physicians treat this type of tumor with medications but in rare cases, surgery may be required.

Low Weight and Excessive Exercise

Women with an excessively low body weight may experience interruptions in hormone function that can cause a lack of ovulation. The Mayoclinic.com warns that women who suffer from eating disorders such as anorexia or bulimia are more susceptible to abnormal hormone shifts. Women who participate in rigorous sports training, such as ballet, gymnastics and running, may notice an interruption of their menstrual cycles.

Hypothyroidism

A condition known as hypothyroidism may cause amenorrhea. Hypothyroidism means that the thyroid gland does not produce enough of the thyroid hormone needed to maintain the body's normal functioning. Thyroid disorders may cause the body to create too much or too little of a hormone known as prolactin. An altered prolactin level causes a disruption in the menstrual cycle.