Knowing and understanding your cycle are important for your everyday life but If you are thinking about starting a family in the near future, now is probably a good time to make sure you understand exactly how and why we have periods. It is actually astounding how much misinformation and uncertainty surrounds a subject that for half of the world´s population is a monthly fact of life and without which there would be no babies!
The menstrual cycle is the monthly sequence of changes a woman´s reproductive system goes through in preparation for a potential pregnancy. During each menstrual cycle, an egg develops and is released from the ovaries. Meanwhile the lining of the uterus builds up in preparation for a fertilized egg. If a pregnancy doesn’t happen, the uterine lining is shed as a menstrual period and the cycle begins again.
The length of the menstrual cycle varies from woman to woman, anywhere from 21 to 40 days, but with an average length of 28 days. Each menstrual cycle has 3 phases:
1. Follicular Phase (Days 1-14)
The first day of your period is also Day 1 of your cycle. A period can last between 2 to 7 days although bleeding is usually heaviest during the first 2 days. You may have a variety of symptoms including cramps, bloating, tender breasts and lower back pain. Symptoms may vary with each monthly period, some periods may cause little or no discomfort, while others may be more painful.
While bleeding occurs at the beginning of this phase your ovaries are, at the same time, preparing to ovulate again. The pituitary gland releases a hormone called FSH (follicle stimulating hormone) which causes several follicles, each containing a single immature egg, to rise on the surface of the ovary. One of these follicles will develop and release an egg. The maturing follicle produces oestrogen which increases during the follicular phase and peaks shortly before ovulation. The menstrual flow has now finished, and the lining of the womb becomes thicker.
2. Ovulatory Phase (Day14)
After release the egg travels down the fallopian tube towards the uterus. Ovulation is the only time in your cycle that you can get pregnant. If the egg isn’t fertilized and pregnancy doesn´t occur the egg will be absorbed into the body. While women often believe that ovulation occurs mid-cycle it actually occurs 12-16 days (the fertile widow) before the next period starts. So, although a woman with a 28-day cycle may ovulate mid-cycle (between day 12 and day 16) if your cycle lasts 32 days you will probably ovulate on day 17 or 18. While the luteal phase remains fairly constant, lasting about 14 days after ovulation (the release of an egg is just a few hours long), the follicular phase can vary in length from 10 to 16 days. If the follicular phase is prolonged, ovulation will be later or even absent.
3. Luteal Phase (Days 14-28)
After the follicle releases its egg, it changes into the corpus luteum. This structure releases hormones, mostly progesterone and some oestrogen. After ovulation the levels of oestrogen fall and the levels of progesterone rise. Higher levels of progesterone cause the body temperature to fluctuate at a higher temperature than in the follicular phase. This minute rise in body temperature therefore is a direct result of ovulation and can be used as a reliable indication that ovulation has occurred.If an egg has been fertilised progesterone will continue to rise, if there has been no fertilisation the progesterone will drop, the lining of the womb sheds and leaves the body as a period. Towards the end of the luteal phase, women may experience a wide variety of signs and symptoms including tender or lumpy breasts, fluid retention, food cravings, bloating, mood swings, irritability and depression. As many as 3 out of 4 women are thought to experience some symptoms of PMS.