By Yolanda Smith, BPharm
There are many possible causes of amenorrhea, which is the absence of a menstrual period in a woman for three or more consecutive months or a delay in menstruation in a girl over the age of 15 who never had a menstrual period.
The most common causes are completely natural and occur when a woman becomes pregnant, is breastfeeding or reaches menopause. However, there are several other causes that may result in amenorrhea, such as certain medications or adverse health conditions.
Natural Life Stages
Natural stages throughout the life of a woman can lead to a temporary or permanent change in hormone levels, which can cause amenorrhea.
For example, when a woman becomes pregnant, amenorrhea is one of the first signs that may indicate that the woman has conceived. This is natural and is not a problem for health. Amenorrhea continues for the duration of the pregnancy and for several months following birth while the woman breastfeeds.
Menopause is the time in a woman’s life when she ceases to menstruate, which occurs around the age of 50. This can also happen earlier and is known as premature menopause if it occurs before the age of 40.
The oral contraceptive pill and other contraceptive methods can lead to amenorrhea in some women. This may continue for some time after the contraceptive is ceased until the body returns to the regular rhythm of ovulation and menstruation.
Other medications that may cause amenorrhea include:
- Antipsychotic medications
- Antidepressant medications
- Hypertension drugs
- Allergy medications
- Chemotherapeutic agents
Women who have an excessively low body weight are more likely have an interruption in the normal functioning of hormones in their body. In some cases, this can halt ovulation and cause amenorrhea. Eating disorders, such as anorexia and bulimia, are associated with amenorrhea for this reason.
Intense physical activity and training for sports can also cause amenorrhea. Women who practice gymnastics or ballet are more likely to be affected, due to the high physical stress and energy expenditure associated with these activities at a professional level. Additionally, excessive stress in daily activities can alter the function of the hypothalamus and alter the production of hormones that regulate ovulation and menstruation.
In most cases, amenorrhea caused by lifestyle factors, such as body weight or stress, is relieved and the regular cycle returns when the circumstances become more normalized.
An imbalance of the hormones that are needed to regulate the menstrual cycle can lead to amenorrhea. There are many possible causes of hormone imbalance including:
- Polycystic ovary syndrome: Constant high levels of hormones rather than fluctuations throughout the normal menstrual cycle.
- Hyperthyroidism or hypothyroidism: Altered levels of thyroid hormones, which are involved in the production of hormones needed for menstruation.
- Pituitary tumor: Abnormal growth in the pituitary gland can alter the levels of pituitary hormones, which are involved in the production of hormones needed for menstruation.
In some cases, abnormal structure of the female sexual organs may be responsible for causing amenorrhea. For example, some women are both without part or all of the reproductive system, which prevents them for menstruating. An obstruction of the vagina, such as a membrane or wall, may block the flow of blood from the uterus or cervix.
Additionally, scarring to the reproductive system, particularly the uterus, can prevent the proliferation and shedding of the uterine lining, which characterizes menstruation. This is often associated with Asherman’s syndrome, treatment for uterine fibroids or following a caesarean section birth.
Reviewed by Jonas Wilson, Ing. Med.
Last Updated: Sep 6, 2016