In some women it may be normal to have less bleeding during menstrual periods. Less blood flow may be genetic and, if enquiries are made, it may be found that woman’s mother and/or sister also have decreased blood flow during their periods. Pregnancy can normally occur with this type of decreased flow during the period. The incidence of infertility is the same as in women with a normal blood flow. Constitutional scanty menstruation perhaps best explained by assuming the presence of an unusual arrangement, or relative insensitivity, of the endometrial vascular apparatus.
Scanty menses or periods can occur normally at the extremes of the reproductive life that is, just after puberty and just before menopause. This is because ovulation is irregular at this time, and the endomaterial lining fails to develop normally. But normal problems at other times can also cause scanty blood flow. Anovulation due to a low thyroid hormone level, high prolactin level, high insulin level, high androgen level and problems with other hormone can also cause scanty periods.
Despite these common causes, hypomenorrhea is still technically an abnormality of the menstrual flow, and other underlying medical problems should be ruled out by a doctor.
Disorders causing scanty menstruation
One cause of hypomenorrhea is Asherman's syndrome (intrauterine adhesions), of which hypomenorrhea (or amenorrhea) may be the only apparent sign. The degree of menstrual deficiency is closely correlated to the extent of the adhesions.
Uterine: Scanty loss sometimes means that the bleeding surface is smaller than normal, and is occasionally seen when the endometrial cavity has been reduced in size during myomectomy or other plastic operation on the uterus. However, it rarely indicates uterine hypoplasia because the presence of this condition in a uterus which is responsive to hormones indicates ovarian under-activity, and this manifests itself by infrequent rather (oligomenorrhea) than scanty menstruation.
Nervous and emotional: Psychogenic factors such as stress due to exams, or excessive excitement about an upcoming event may cause hypomenorrhea. Such factors suppress the activity of the centers in the brain that stimulate the ovaries during the ovarian cycle (to secrete hormone like estrogen and progesterone), and may result in low production of these hormones.
Low body fat: Excessive exercise and crash dieting can cause scanty menstrual periods when the proportion of body fat drops beneath a certain level. It may cause a total absence of periods (also called amenorrhea).