Ovarian cycle

A normal Ovarian cycle can be divided into 3 phases: follicular, ovulatory, and luteal.

During the Follicular phase, the small increase in follice stimulating hormone (FSH) levels early in the cycle stimulate growth of the follicle and enhances it's production of the estrogens.

The Ovulatory phase occurs at mid cycle and arises from a complex interplay between multiple hormones.

Estradiol which is the most biologically active form of estrogen, generally exerts strong feedback inhibition on gonadotropin release, particularly FSH.

If estradiol levels become too high at a particular time in the cycle, however, the relationship is reversed.

At midcycle, both luteinising hormone (LH) and FSH secretion are enhanced owing to a rapid, sustained rise in estradiol production by the maturing follicle.

The LH surge is responsible for ovulation and formation of the corpus luteum (luteinisation).

The Luteal phase follows ovulation when the corpus luteum begins to secrete large amounts of both estradiol and progesterone, which suppress LH and FSH secretion throughout most of the luteal phase of the cycle.

Unless pregnancy occurs, the corpus luteum degenerates 10 to 12 days after ovulation, leading to a sharp decline in estradiol and progesterone levels.

In general, the length of the luteal phase is fairly fixed at around 14 days.

Variation in the duration of the follicular phase is primarily responsible for the differences in cycle length among women.

Treatment with Progesterone

Spotting

If spotting occurs during a normal cycle, continue using natural Progesterone, do not stop treatment.

It is also possible to increase the natural Progesterone level for a few days to stop or clear spotting.

Full period

If a menstrual period occurs unexpectedly during a normal cycle, stop the Natural Progesterone immediately. Call the first day of menstruation day 1 and restart Natural Progesterone as per prescribed program.

Hot Flushes

If hot flushes return after having been free of hot flushes, check for dietary changes, changes in medication or changes in stress levels.

Typical dietary changes include changes in coffee/tea or alcohol consumption.

Alcohol and caffeine have quite profound effects on vasomotor control and can lead to unexplained flushing and night sweats.
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Medicine changes include abruptly stopping estrogen treatment, leading to estrogen withdrawal. A significant change in stress levels can cause flushing.

As a rule, increasing the level of Natural Progesterone over 40mg per day, will not alleviate hot flushes that have returned, it is important to rectify the cause of the returning flushing symptoms.

Cycling women

It is important for cycling women to double the level of Natural Progesterone during the last week of the cycle, so that there is a sudden large drop in progesterone levels at the end of the cycle, which causes the body to start menstruating. If your cycle is normally less than 28 days, count back from your last day to maintain the same number of days with the double dose of Natural Progesterone.

The menstrual cycle is regulated by a complex interaction between the hypothalamus, anterior pituitary, ovaries and endometrium, which is diagrammatically represented in Figure 1.

It is convenient to think about this dynamic hormonal interaction from the perspective of the endometrium, which is the target organ.

Endometrial Cycle

The Endometrial cycle can be divided into 3 phases; Proliferative, Secretory and Menstrual. Each phase is characterised by a different hormonal combination.

The Proliferative phase occurs in the first half of the cycle (from days 5 to 14) and is dominated by the effects of oestrogen, which is secreted by the developing ovarian follicle.

The principal effect of oestrogen is to stimulate growth of the endometrium.

The Secretory phase occupies the second half of the cycle (from days 15 to 28) and is predominantly regulated by progesterone, which is secreted from the corpus luteum.

Progesterone antagonises the effects of oestrogen, halting growth of the endometrium and stimulating the differentiation into a secretory epithelium.

If conception does not occur by about day 23, levels of estrogen and progesterone fall sharply owing to a degeneration of the corpus luteum, leading to a sloughing of the endometrium and the Menstrual phase commences (days 1 to 4).

As levels of oestrogen and progesterone fall, follicle-stimulating hormone (FSH) levels begin to increase, which initiates the process of follicular growth and development for the next cycle.

The Stages of the Menstrual Cycle

 Days 15 – 22 The Ovum travels through the fallopian tubes

 Ovulation:  The mature ovum is released around Day 14

 Two important hormones govern the menstrual cycle:

• Estrogen
• Progesterone
   

Hormones are chemical messengers, which the body uses to send instructions from one part of the body to another. The levels of estrogen and progesterone signal the changes that happen during the menstrual cycle. It is important to remember that these hormones also influence other parts of the body. For example, estrogen helps a woman retain calcium in her bones. The influence of these hormones is also thought to cause many of the symptoms of premenstrual syndrome.

A woman's menstrual cycle is said to begin on the first day of her bleeding. A woman's menstrual cycle only occurs if she is not pregnant.

Day 1

• estrogen and progesterone levels are at their lowest level
• the inner lining of the uterus, or endometrium is discharged as menstrual blood
• the unfertilized ovum produced in the last cycle is also discharged

 Day 2-12

• menstruation continues for three to six days for most women
• when menstruation begins, a new ovum begins to mature in the ovaries
• the sac around the maturing ovum produces estrogen, increasing the levels in the body . increasing estrogen levels prompt the uterine lining to thicken beginning around day nine

 If a woman becomes pregnant this nutrient-rich lining supports the developing embryo.

Ovulation

• estrogen levels peak
• around Day 14 the sac containing the mature ovum, splits open releasing it from the ovary
• This is called ovulation. Some women feel a slight pain when this occurs. This is called a mittelschmerz. Some women also have spotting (light bleeding) at this time.
• the endometrium continues to thicken

Days 15-22

• the empty sac left in the ovary begins to produce both estrogen and progesterone (This sac is called the corpus leuteum)
• the uterine lining continues to thicken thanks to estrogen produced in the ovary
• the ovum travels from the ovary down the fallopian tube. If the egg is going to be fertilized (unite with a sperm) it is likely to happen now. When a fertilized egg reaches the uterus, high levels of estrogen and progesterone signal the uterine lining to allow it to implant on the wall of the uterus.
  

Day 22 - Day 1 of next cycle

• around this time the corpus luteum stops producing estrogen and progesterone.  If the egg has not been fertilized, levels of both estrogen and progesterone will begin to drop.
• blood vessels in the uterine wall contract and spasm due to the lack of estrogen and progesterone

the uterine lining is shed as menstrual blood beginning the first day of the new cycle