A brief overview of a woman’s cycle;
A woman’s menstrual cycle is a lot more than just her period; but is does start there. There are four phases of a menstrual cycle.
Phase 1; Menstruation/ Period
The first day of a woman’s cycle is the first day of her period. The length of your period will vary between three and seven days. Hormonally, levels of oestrogen and progesterone are at their lowest.
Phase 2; Follicular phase
This is the time before ovulation occurs. It starts when your period starts and ends at ovulation. The pituitary gland is sent a signal by the hypothalamus to prelease follicle – stimulating hormone (FSH). The role of FSH is to stimulate the ovaries to produce follicles (about 5 to 20). However, only the healthiest egg (occasionally two) will mature. It is this maturing egg that sets off a surge in oestrogen, which will cause the lining of the uterus to start to thicken. The follicular phase can vary quite a bit in length, averaging between 14 and 21 days. However it can occur as early as day 11 and as late as day 27.
Phase 3; Ovulation
Ovulation is the release of an egg from the ovary. The exact time when ovulation occurs can vary from cycle to cycle, but happens around 13 to 15 days before the start of the next cycle. Following your period, the levels of oestrogen increase as the follicle (soon to be egg) grows in the ovary. When oestrogen levels are high enough, a signal is sent to the brain (pituitary gland). It triggers an increase in the production of Luteinising hormone (Lh) and follicle stimulating hormone (fsh). Symptoms of ovulation include a slight rise in basal body temperature, and a change in cervical fluid that has the consistency of egg white.
Phase 4; Luteal phase
The luteal phase is the time after ovulation until the last day of your cycle (before period starts. The Egg has been released from the ovary and is making its way to the uterus via the fallopian tube. The structure left behind when an egg is released is called the corpus luteum, which produces progesterone for 12 – 15 days. The purpose of progesterone in the luteal phase is to cause the uterine lining to thicken in preparation for a fertilised egg to implant.
If conception doesn’t occur, the corpus luteum shrinks and dies, causing the level of progesterone to drop. As a result of this the uterine lining will start to shed, which is when the next cycle starts (your period starts).
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