American College of Embryology

Miracle Babies: Chapter 11 Female Fertility                      Send Link
Female Fertility
Are You Ovulating?

 

Clues from Your Menstrual History

The complexities of regulating ovulation remind me of the difficulty a musical conductor faces when combining a hundred individual performances into a symphony. Although each individual plays an important part in the production, the overall performance ultimately depends on the precise coordination of all the players. If even one instrument is unsynchronized or off-key, the delicately balanced harmony can turn into disorganized noise.

In the "ovulation symphony" harmony can be disrupted by disturbances in the menstrual cycle. Instead of an unwavering pattern repeated from month to month, infertile women frequently complain that their periods are irregular or have stopped altogether, and some women have never experienced menstrual flow. So, like the semen analysis, your menstrual history serves as a simple screening test to guide my investigations. It won't tell me precisely what the fertility problem is, but it will tell me where to look for further clues.

 

The Three Types of Menstrual Patterns

The Regular Menstrual Period
The critical point about this category is that your period is regular from month to month, beginning like clockwork every twenty-five days or every thirty-five days, for example. If your periods are regular, you are probably ovulating. The consistently irregular menstrual cycle, however, where one month you begin menstruating after twenty-five days, the next month after thirty-four, and the next in thirty, may indicate that you have a fertility Problem. If a woman reports a regular menstrual history, I'll usually look at other areas of the reproductive system for a breakdown in the fertility formula.

Irregular Menstrual Periods or Amenorrhea for Six or More Months
This is the most common complaint found with fertility problems, The woman's menstrual periods occur infrequently and at unpredictable intervals. Some women, like Kathy S., even report that at some point their periods stopped altogether. Because these women are capable of menstruating (as demonstrated by their history), there is a good chance that with the proper treatment ovulation and a regular menstrual cycle will resume.

Nonexistence of the Menstrual Period
Women who have never menstruated may have genetic abnormalities, congenitally deformed reproductive organs, delayed puberty, or a pituitary malfunction. If by the age of sixteen a woman has not started menstruating, she should be concerned. It is important to diagnose the problem early and to determine if such women will respond to hormonal therapy or surgical correction. The emerging new technologies offer the most promise to these people.

 

What Is Ovulation?

Ovulation is a fascinating harmony performed by several different "players" — your hypothalamus, your pituitary gland, and your ovary. Your hypothalamus maintains the hormonal "tempo" by regularly pulsing GnRH (gonadotropic-releasing hormone). These pulses stimulate your pituitary gland to produce LH (luteinizing hormone) and FSH (follicle-stimulating hormone).

 


 

 


Your pituitary gland plays the chorus—a pattern repeated from month to month in a beautifully precise rhythm. Each month the pituitary secretes FSH to stimulate the development and growth of over one thousand eggs. This phase in the ovulation cycle is known as the follicular phase. At puberty a woman has about half a million primitive germ cells. Only four or five hundred, however, will ever reach maturity. Due to some mysterious mechanism which we don't yet understand, usually each month only one of the thousand developing eggs becomes dominant and grows to maturity. This egg, or ovum, is cradled within the ovary in a tiny, fluid-filled capsule called the follicle.

During the follicular phase of your cycle, LH acts on the ovary's theca cells to initiate estrogen production by the granulosa cells. The estrogen makes the follicle even more responsive to FSH, which further stimulates follicular growth and development of the egg. As the follicle expands toward the surface of the ovary, the egg increases in size nearly forty times. The ovary tells the pituitary when it needs more or less FSH to finish the job of egg maturation by making a feedback hormone called inhibin (folliculostatin) .

Shortly before ovulation, the genetic material (nucleus) in the egg divides (meiosis) to half the number of chromosomes in the cell. If the egg is fertilized a second meiotic division leaves the ovum with twenty-three chromosomes—a perfect complement to the sperm's twenty-three. To form an egg, the female germinal cell divides twice, as does the male germinal cell. During female germ cell divisions, however, the "surviving" ovum jealously hoards the bulk of cellular material (nutrients) and casts off the excess genetic material (polar bodies). The egg or (if the egg is fertilized) the embryo survives on these nutrients until the embryo successfully implants in the woman's uterus.

 

 

Continued