MENSTRUAL IRREGULARITY

The duration of the menstrual cycle is calculated as the number of days between the first day of bleeding to the first day of bleeding of the next menstrual period. Not every woman has a cycle of exactly 28 days and the normal menstrual cycle can vary from 21 to 35 days.
It is not uncommon for the menstrual periods to become irregular and less frequent. If a woman who previously had regular monthly cycles fails to menstruate for over three months, she has what doctors call amenorrhoea, and this is not a normal state in pre-menopausal women.

WHAT ARE THE CAUSES OF INFREQUENT MENSTRUATION?
In the vast majority of cases a hormonal imbalance resulting in failure to ovulate is the cause, but disorders of the uterus and a possible blockage of the cervix or vagina must be checked. Hormonal imbalances disturb the menstrual clock in the hypothalamus and the sensitive communication link between the hypothalamus, pituitary gland and ovaries.

CHANGES IN BODY WEIGHT
The menstrual clock can be switched off by rapid or severe changes in body weight with either weight loss or weight gain having this effect.
Fat produces both female and male sex hormones, and so very thin women have low levels of these hormones. In addition, if the menstrual clock has switched off as a protective mechanism against extreme thinness, ovulation will not occur and so the ovaries will produce very little sex hormones. These low levels of sex hormones cause menstrual bleeding to cease. If weight can be gained to achieve a normal body weight relative to body height, the menstrual clock should restart causing a resumption of regular menstrual bleeding.
Overweight women tend to overproduce female and male sex hormones from their fat. They often have polycystic ovaries which do not ovulate regularly and produce plenty of oestrogen but insufficient progesterone. They also fail to menstruate regularly as their uterus is exposed to constant high levels of oestrogen. Once again, the achievement of a normal body weight relative to body height will usually bring back regular ovulation and normal levels of the female and male sex hormones.

EXERCISE
Excessive exercise can switch off the menstrual clock resulting in amenorrhoea. Such sportive women may be muscular, but usually have low amounts of fat and thus low levels of sex hormones. If the amenorrhoea persists they will be at a higher risk of osteoporosis despite their vigorous physical workouts.

STRESS
Stress and emotional trauma can act on the hypothalamus to switch off the menstrual clock and in such cases menstruation may not resume until a woman is feeling happy and relaxed. Some women lose their menstrual periods after a traumatic relationship or divorce and find that their periods return when they fall in love again.

IMBALANCE OF THE PITUITARY GLAND
Excessive amounts of the lactation hormone Prolactin, switch off the menstrual clock and the ovaries which is why it is normal for breastfeeding mothers to miss their periods for six months or more.
If a non-lactating woman has excessive Prolactin production from the pituitary gland she may stop menstruating which is not a normal situation. In such cases the excessive Prolactin may result from medications such as anti-depressants or a small tumour in the pituitary gland that overproduces Prolactin. The drug bromocriptine (Parlodel) can correct this situation restoring regular menstruation and fertility.

PREMATURE MENOPAUSE
Some women stop menstruating in their 20s and 30s because of a premature failure of the ovaries. This is called a premature menopause and can be diagnosed with blood tests. These women have used up all the eggs from their ovaries and need to receive Hormone Replacement Therapy (HRT).
In some women menstrual bleeding may not cease altogether, but rather become extremely light with perhaps no more than spotting for a day or so. This is called "hypomenorrhoea". Common causes of hypomenorrhoea are advancing age, weight loss, heavy athletic training or imbalances in other hormonal glands, such as the thyroid or adrenal glands.

TREATMENT OF AMENORRHOEA
If a woman with absent menstruation does not want to become pregnant the best treatment is the Oral Contraceptive Pill (OCP). This will restore regular menstruation and protect the bones from osteoporosis in the underweight woman with low oestrogen levels. In overweight women with high oestrogen levels, the OCP will protect the uterus from cancer.
A tailor-made OCP can be designed to reduce excessive levels of male hormones in the woman with amenorrhoea associated with acne and facial hair.
If pregnancy is desired, it is necessary to stimulate ovulation with fertility drugs such as clomiphene or gonadotrophin drugs. These drugs should be given by a specialist gynaecologist.
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