It is true that most women do not like the monthly periods, which are often accompanied by PMS; nevertheless, a missed period or amenorrhea is not something anyone wants. In general, there could be no serious cause for a missed period, though in some cases it could be a clue to hormonal imbalance, stress, pituitary tumors, PCOS and other such changes in the body which can be the reason behind the absence of period.
Typically women have 11-13 periods in a year, depending on their menstrual cycle which can range between 21-35 days. The menstrual cycle begins before the age of 15 under normal conditions, but in case of primary amenorrhea a girl may not start menstruating even after reaching 15. In secondary amenorrhea, the woman who is having her regular periods may miss it in between.
It is normal to miss periods when a woman is pregnant, breast feeding, or on medications like chemotherapy; in which case it should not be considered as missed periods. However, if the period is absent for more than 45 days after LMP without any reason, then it is sensible to bring it to the notice of a gynecologist who may either rule out any health issues related to the symptom or treat it accordingly.
Premature Menopause
Women reach menopause normally around the age of 50 years. However, some of the causes like genetics, illness or surgeries may lead to menopause in a woman before the age of 40 yrs, when it is considered premature menopause. With the onset of premature menopause the woman will miss her periods initially, before finally stopping the menstruation all together.
Hypothyroidism
Hypothyroidism is known to cause amenorrhea because of decrease in production of thyroid hormone Prolactin. The decreased levels of prolactin can lead to missed periods, which will correct itself once the hormonal balance is restored.
Stress and Depression
Emotional stress temporarily affects the hypothalamus which in turn decreases the level of hormone GnRH which is responsible for ovulation and menstruation. Relaxation and rest should allow the periods to commence normally once again without interference.
Weight Issues
Being underweight or overweight can lead to problems with periods for different reasons. Overweight women run the risk of infertility as the blood sugar levels can affect the hormonal cycle interfering with ovulation and menstrual cycle. Fortunately, losing even 10% of weight can correct the problem and restore fertility in many cases.
The loss of body fat causes disturbance in hormonal balance which is the reason for missed periods in women who are underweight.
The loss of fat is one of the main reasons why women athletes, ballet dancers, and gymnasts do not get regular periods.
Polycystic Ovary Syndrome
Polycystic ovarian syndrome is known to cause amenorrhea due to excessive production of hormones estrogen and androgen, which leads to imbalance of the hormones estrogen and progesterone required for ovulation and menstruation.
Pituitary Tumors
The pituitary gland is responsible for production of hormones required for regulation of ovulation and menstruation. Cancerous or non-cancerous tumors in the gland may cause imbalance in the hormones leading to amenorrhea.
Contraceptives
Women who have opted for contraceptives like birth control pills, intrauterine devices, injected or implanted contraception may find their periods missing due to the continuous presence of hormones in the body.