Have you ever noticed what really monitors your monthly cycles? How do you get your periods every month? What controls it? Why do some women have short cycles while some have long cycles? Some bleed heavily whereas some experience scanty periods. All this is controlled by chemical messengers called hormones.
Every month, nature prepares the womb for pregnancy by a series of complex hormonal interactions controlled by our nervous system, if pregnancy does not happen; the prepared bed (endometrium) sheds down. This keeps on happening till pregnancy comes or till women stop menstruation which is till the age of menopause.
Your cycle is controlled by your hormones. Ovaries receive signals from the higher center that is, the hypothalamus and pituitary and in turn the ovaries send feedback to these higher centers. The hormonal signals prepare the bed for pregnancy. The two important hormones which regulate our cycles are osestrogen and progesterone. Normal cycle length varies from 21 to 35 days. Cycle length depends on the day of ovulation. The day the bleeding start is usually the first day of the cycle. The menstrual cycle is divided into two phases depending upon ovulation. The phase before ovulation is known as luteal or follicular phase and the phase after ovulation is called proliferative phase.
Our higher centre produces a hormone called FSH (Follicle Stimulating Hormone) under the influence of FSHRH (FSH Releasing Hormone) which acts on the ovaries to prepare for ovulation. Ovaries have multiple fluid filled spaces called follicles which release a mature egg. Under the influence of FSH and by natural selection, one of the follicles becomes dominant and produces the egg. There is another hormone which starts increasing and it is called estrogen and this is produced by follicles which are stimulated by FSH. Estrogen is the predominant hormone during the initial phase and is responsible for endometrial thickness and it also causes cervical mucus thickening.
Ovulation then happens under the influence of LH (Luteinizing Hormone), the continuously increasing estrogen causes a LH surge or rapid rise of LH and then the dominant follicle ruptures and releases the mature egg. This process is called ovulation. The fallopian tube with their motile fimbria catches the egg is transported in the tube. Some women may experience pain in the mid-cycle and this is caused by the rupture of the follicle to release the egg.
As soon as ovulation happens, there comes another hormone called progesterone and this helps estrogen to maintain the thick lining and be ready for implantation. There is also a symptom complex known as premenstrual syndrome which some women may experience just before and during periods which happens due to high levels of hormones in the body. The symptoms may include headaches, dizziness, bloating, irritability, anxiety, mood changes, vomiting, fever, and even depression.
Usually women think they ovulate on the 14th day of the cycle but it varies from cycle to cycle and woman to woman. They ovulate somewhere in the middle of the cycle but as mentioned earlier, cycle length varies, so does the day of ovulation. Usually the first phase of cycle varies and the later phase has somewhat a fixed duration of 14 days. For example if somebody has a cycle of 35 days, her ovulation may be happening around day 21.
There are also some myths associated with menstruation, so you should be aware of the facts about menstruation. Every woman may not have a 28-days cycle, every woman may not ovulate on the 14th day of the cycle, a woman may menstruate even while pregnant and every woman may not even bleed every month.
One more important chemical messenger in our body is the thyroid hormone which can also affect periods. There are two types of conditions when periods are affected. In hyperthyroidism that is when the thyroid gland is overactive, periods may be scanty or absent whereas in hypothyroidism that is when thyroid is hypoactive, there may be heavy and prolonged periods. So, it is very important for a woman to understand her monthly cycle and to seek medical help if any variations happen.