Before looking into progesterone deficiency or Estrogen dominance it’s important to understand what classify’s as a normal menstrual cycle. We need to understand what happens during Ovulation in order to be able to fully understand Anovulation. 
menstrual cycleThe menstrual cycle is sequence of precisely timed hormonal events that when combined create the environment for pregnancy to occur and develop successfully. The menstrual cycle has three distinct phases

Female babies are born with 2 million immature eggs in the ovaries. With age these eggs degenerate so by the time of puberty girls have around 300,000 eggs remaining. At most, 500 of these eggs will mature during the menstrual cycles between puberty and menopause.


Follicular phase
The first part of the menstrual cycle is called the follicular phase, when an egg ripens in a follicle of your ovary and the tissue cells lining of the wall of the uterus (endometrium) multiply and grow in preparation to receive a fertilized egg (proliferative endometrium). Ovulation should occur around Day 13 to 15 of a standard 28-day cycle.

Estrogen rises at the start of the fertile period, and luteinizing hormone (LH) rises 24-36 hours before the egg is released. The breasts may be tender and your cervix (the area where the top of the vaginal passage joins the uterus) will soften, rise, and open slightly. Having intercourse daily during the mid-cycle fertile period will maximize the likelihood of pregnancy.


Figure 1 Normal endometrium is less than 5 mm thick.

Luteal phase
The second part of the menstrual cycle is the two weeks from the time you release an egg until menstruation begins, called the luteal phase. It gets its name from the corpus luteum (yellow body) in the ovary, which is the empty yellow socket (follicle) from which the egg was released.
The corpus luteum releases the hormone progesterone during the luteal phase to further prepare the endometrium for receiving the fertilized egg. This secretory endometrium becomes thicker, more nutritious and develops a better blood supply to nuture the fertilized egg.

The luteal phase last for at least 12 days. If your luteal phase lasts for less than 10 days, then you have a short luteal phase and your estrogen levels are most likely not balanced by a sufficient amount of progesterone.


Withdrawal bleeding
The third part of the menstrual cycle is withdrawal bleeding or period. This happens only if no fertilization takes place. Most women have one menstrual cycle every 22-35 days, most commonly 28 days.
A few women have a regular cycle of 18-40 days, and if that is consistent, fairly painless, and not excessively heavy or light, then it is considered a normal variation.
Calculate Day 1 of your cycle as the first day you start bleeding. Day 1 should be the day when the heaviest bleeding occurs. Bleeding should last only 3-5 days. Normal blood loss is 10-35 ml, or 2-7 soaked sanitary pads per cycle. The absolute maximum blood loss during a heavy cycle should be 45-60 ml per cycle. If it exceeds this amount, the woman is at risk of developing iron deficiency anemia.

If you soak 16 pads or more per cycle, then you have menorrhagia and are at risk of developing iron deficiency anemia. Normal menstrual blood is dark or brownish, not bright red.
Normal menstrual blood does not clot easily because it:


female menstrual cycle

Figure 2 Female Menstrual Cycle 2 by Lyrl, May 20, 2007.

In order for a woman to ovulate, she requires these hormones in perfect balance:
1. Gonadotropin-releasing hormone (GnRH) from the hypothalamus in the brain
2. Follicle stimulating hormone (FSH) from the pituitary gland in the brain to stimulate egg growth in the ovary
3. Thyroid stimulating hormone (TSH) from the pituitary gland to stimulate the thyroid gland in the neck
4. T3 and T4 from the thyroid gland to stimulate metabolism and allow ovulation
5. Luteinizing hormone (LH) from the pituitary gland to release the egg from the follicle in the ovary
6. Estrogen from the ovary to stimulate the lining of the uterus to grow (follicular phase)
7. Progesterone from the corpus luteum (yellow body on the ovary from which the egg burst) to mature the uterine lining to be nutritious for the fertilized egg and support a pregnancy.

Progesterone levels drop and causes the endometrial lining to shed in a menstrual period if the egg
is unfertilized.



Understand more on Ovulation and Anovulation:

What is Ovulation and Anovulation?

All about Anovulation and Ovulatory changes with age

More serious medical conditions associated with Anovulation

The information in this article has been taken with permission from the official Lawley booklet on Understanding Anovulation.