Menstrual Cycle
Women’s menstrual cycle – a rough guide
The first day of menstruation is the first day of the cycle. Any brown / pink discharge (spotting) before this shall be counted as the last days of the previous cycle.
The course of a cycle starts with the period (menstruation). This cleans up after the last cycle and you start fresh again. The eggs start to mature from the stimulation of FSH, LH and estrogen (see hormone graph). LH gets a sudden upswing, and this rise in the hormones sparks the ovulation. The egg usually comes some time between 13 and 36 hours after this top.
When the ovulation has passed, the egg sack transforms into the corpus luteum, producing progesterone. You are then in the luteal phase. A luteal phase that lasts 18 days or more usually means you are pregnant. A luteal phase of 10 days of less – also called the defect luteal phase, can create trouble for the egg as it doesn’t have enough time to attach before the period starts again.
Towards the end of the cycle (approximately two weeks after ovulation for most people) and corpus luteum hasn’t received a message from a fertilized, buried egg to stay alive beyond its normal life, it will shrink and die. The progesterone production will then gradually diminish and finally stop. This leads to the womb lining being pushed out: menstruation. After this, a new egg starts to mature and ovulate etc…
Length of cycles
We are taught that a woman’s cycle lasts about 28 days and the ovulation occurs on day 14, but this is a myth. It is simply a statistical average. The length of the cycle and when ovulation occurs varies a lot from women to women. It can also vary between one woman’s cycle to her next.
A typical ”normal” cycle starting with the period, is usually 25 – 36 days long and with ovulation between day 12 and 23.
However, it’s not this way for everyone. Even though the cycle usually has a stable and regular length it is not certain that ovulation occurs on the same day of the cycle every time. There is also no guarantee that all cycles in the future will stay consistent in the long run.
When a cycle varies in length it is the time between the period and ovulation that varies. It is the time of ovulation that determines how long the cycle will be, because the luteal phase has a relatively determined length because of corpus luteums length of life. The length of previous cycles have no affect on the length of future cycles. The body and the hormones don’t care about statistics or calendars.
What happens when you get pregnant:
The fertilization happens in the fallopian tube right after the ovulation, because the egg doesn’t live longer than 24 hours. The sperm can live for up to 5 days in the fallopian tubes, the uterus and the neck of the womb if the conditions are optimum.
The egg travels down the fallopian tube and into the uterus. Approximately 4 days after ovulation, the implantation happens. The egg is in the uterus ”looking” for a good place to settle down.
6 – 8 days after ovulation, the egg digs itself down and starts to secrete hCG (human chorion gonadotropin). This hormone stimulates the corpus luteum to increase the production of progesterone and live beyond its normal life span. This increase in progesterone can be seen if the basal temperature increase (even more than before ovulation). This way it is possible for some to discover the pregnancy only a week after ovulation.
Menstruation will fail to appear about two weeks after ovulation, and the most people will test positive using a pregnancy test.