All About Periods
What is Periods?
Why they occur?
The process is an intricate one, controlled by the brain and a complex, hormone-signaling system. Although menstrual cycles can vary in length, the number of days between ovulation and your menstrual period is consistent-approximately 14 days (11-16 is the normal variation). For example, if your typical cycle length is 31 days, then the first half of the cycle is 16 days and ovulation occurs on the 17th day.
But the menstrual period is only one part of the cycle that takes place each month until you are in your 40s or 50s.
Phases of Menstruation
On day one of the cycle, your menstrual period begins. Every month, the uterus in your body builds up a fresh new lining of blood and tissue. The purpose of this process is to help nourish a developing baby if you are pregnant. When this lining, called the endometrium, is not needed to nourish a baby, it leaves the uterus, travels through the cervix and the vagina, and trickles out of the vaginal opening. This menstrual blood, called the period, may be bright red, light pink, or even brown. A period usually lasts about three to seven days. The normal amount of menstrual flow is usually about 1/4 of a cup.
During this phase, some of the ova, or eggs, in your ovaries are maturing and moving toward the surface. One of these eggs (or sometimes two) matures each month.
Ovulation is the name of the event that takes place when one of the ovaries releases a mature egg. The egg travels out of the ovary, into the nearest fallopian tube and into your uterus. As the egg moves down the fallopian tube, which takes several days, the lining of the uterus continues to grow thicker and thicker.
During this phase, if you become pregnant, the egg moves into your uterus and attaches to the endometrium. If you are not pregnant, the lining of the uterus is shed through the vaginal opening. Then, a new menstrual cycle begins.
When They Start?
Generally, girls can expect a first period about two to three years after the first signs of breast development. There are several things that can affect the onset of menstruation. One thing is genetics. The age when your mother had her first period may be a clue. Your weight may also have an effect-either too thin or too heavy. Athletic girls also tend to start menstruating later.
In the final stages of puberty, young women reach physical, emotional and sexual maturity. They grow to their full height, breasts reach their full size, and girls develop a regular pattern of menstruation.
What to Expect?
A. Premenstrual Syndrome (PMS)
In historical and modern times, many negative connotations regarding menstruation have existed, contributing to some women’s unpleasant expectations of the premenstrual phase. However, Premenstrual Syndrome (PMS) was first noted as a true medical disorder by the American Gynecologist, Dr. T. Frank in 1931.
The medical community refers to PMS as a condition that is characterized by a constellation of physical and emotional symptoms that have a significant impact on a woman’s day-to-day activities. This is in contrast to the common occurrence of premenstrual symptoms that many women, including you, may experience.
B. Symptoms of PMS
The criteria that physicians need to diagnose PMS are as follows: five (or more) of the following symptoms must occur during the premenstrual phase and be absent after menstruation. Also, at least one symptom must be from Group A.
Depressed mood, feelings of hopelessness
Sudden and dramatic mood swings
Decreased interest in usual activities
Difficulty in concentrating
Fatigue, lack of energy
Change of appetite, overeating, food cravings
Sense of being overwhelmed
Physical symptoms such as breast tenderness or swelling, headaches, joint or muscle aches, bloating, weight gain
In addition, for a positive diagnosis of PMS, it is crucial that these disturbances interfere markedly with work, school, or personal relationships. The cyclic nature of these symptoms cannot be relied upon from memory. You must chart them on a daily basis for at least two to three months.
Finally, these symptoms cannot be a worsening of a psychiatric disorder such as Major Depression or Anxiety Disorder. Only 50 percent of women who visit their physicians believing that they have PMS actually meet the above criteria and have the diagnosis of PMS confirmed.
If you suspect you have PMS, it is imperative to relate the occurrence of the symptoms to the menstrual cycle. However, it is equally important for you to evaluate the stresses in your professional and personal life, since these may have a significant impact on how premenstrual symptoms are expressed.
Severe premenstrual symptoms
Some women experience very severe PMS. Symptoms of serious psychiatric problems, such as depression or panic attacks, are often most extreme during the premenstrual phase each month and studies have shown that women’s suicide attempts, psychiatric hospital admissions, and violent criminal acts are most likely to occur in the premenstrual days. If you feel that you may hurt yourself or someone else, you should seek immediate medical attention. Fortunately, this is extremely rare.
There are no specific physical findings or laboratory tests that can diagnose PMS. There is also no symptom that is unique to PMS. The only way to determine whether or not you suffer from PMS is to record the timing and severity of your symptoms-both emotional and physical-throughout your menstrual cycle on a daily basis for two to three months.
In addition to the symptoms, monitoring basal body temperature (lowest body temperature during sleep) and vaginal secretion will contribute useful information to confirm when ovulation occurs. To accurately diagnose PMS, your physician will rely upon this charting. It is also useful to gauge your response to therapy.
When working with a doctor to confirm PMS, other disorders must be eliminated, since many symptoms of PMS resemble those of other underlying conditions. Your doctor may want to do a physical examination and a pelvic exam to rule out gynecologic problems.
In cases where fatigue is a major symptom, a blood test may be done to rule out anemia, hypothyroidism, and contributors to Chronic Fatigue Syndrome. It is also important to be aware that more serious psychiatric problems may have a cyclic pattern of worsening emotional symptoms in the premenstrual phase. For example, depression is very common in women and often worsens during premenstrual days.
D.Possible Causes of PMS
PMS has been called everything from a hormonal dysfunction to a mental illness to the feminist issue of the 80s. Although it is known that PMS is associated with ovulation, the true cause remains unknown.
It is clear that two components are essential for PMS to occur. The first is the “trigger,” which is clearly identified as ovulation and the resulting, reproductive hormonal changes. The second is the “vulnerability” to the “trigger” that produces the mood changes of PMS. What makes one women “vulnerable,” and another not, is unknown.
This is the key to identifying the cause of PMS. Many factors have been suggested, but refuted, as contributors to the “vulnerability,” such as a woman’s social and economic status, number of children, diet, amount of exercise, stress level, personality, and characteristics of the menstrual cycle.
However, current data supports serotonin, a chemical in the brain, as having an important role in PMS. While no other cause has been nearly as conclusive as serotonin, other possible factors have been investigated and are interesting to consider.
Some theories that have been suggested include:
Cyclic fluctuations in reproductive hormones
Abnormal thyroid function
Serotonin is a neurotransmitter. A neurotransmitter is a chemical that is involved in sending messages along nerves in the brain, spinal cord, and throughout the body. Serotonin affects mood. Impaired serotonin activity has been linked to symptoms of depression, anxiety, impulsivity, aggression, and increased appetite. Since depression is also a major symptom of PMS, scientists have questioned the role of serotonin in PMS. Abnormal serotonin levels and activities have been found in women suffering from PMS. Furthermore, drugs that enhance serotonin activity, called specific serotonin reuptake inhibitors (SSRI) (e.g., Prozac, Zoloft, Paxil), are effective in the treatment of PMS.
Cyclic fluctuations in reproductive hormones
While it seemed logical to many that the reproductive hormones involved in the menstrual cycle were the cause of PMS, research has proven that there are no differences in estrogen, progesterone, FSH, LH, prolactin, and testosterone levels between women with and without PMS. This only confirms that ovulation acts as the “trigger” but is not in itself the cause.
In the past, progesterone supplementation was supported as a treatment for PMS, but has been proven to be ineffective. The only hormonal therapy that works is a regimen that prevents ovulation from occurring.
Abnormal thyroid function
Thyroid disease is common in women. Symptoms of hypothyroidism, or low activity of the thyroid gland, can resemble symptoms of PMS. For this reason, it was thought that the thyroid gland played a role in the cause of PMS. If you suffer from PMS-like symptoms, you should get your thyroid checked.
However, it is clear that the majority of women with PMS have completely normal thyroid function. Thus, supplementation with thyroid hormone in the treatment of PMS is not helpful and may, in fact, be dangerous.
Endorphins are opium-like chemicals manufactured by the body. Opium-like chemicals, including endorphins, are involved in the sensation of euphoria and the perception of pain. Thus, some have proposed that PMS is a state of endorphin deficiency. Endorphin levels in the blood do fluctuate. However, these levels are not felt to reflect the activity of endorphins in the brain. Therefore, there is not enough evidence to support this theory.
Scientific research has not been able to confirm a difference in the levels of vitamins and minerals between those women with symptoms of PMS and those without. One particular vitamin that has received a great deal of attention is Vitamin B6. Vitamin B6 plays an important role in the synthesis of dopamine, a neurotransmitter that may also be involved in physical and emotional well-being. Thus, Vitamin B6 deficiency has been hypothesized as a cause of PMS.
Some researchers have shown improvements in PMS symptoms in women taking vitamin B6 daily, while others have not. However, it is important to limit the amount of vitamin B6 that you take, since nerve damage has been reported. Therefore, you should only take Vitamin B6 supplements with the supervision of a doctor.
A. What Causes Cramps?
Each month the lining of the uterus (the endometrium) builds up in preparation for a possible pregnancy. If a pregnancy occurs, the fertilized egg attaches itself to the lining to be nourished as it develops into a baby. If the egg is not fertilized, the lining is not needed. It breaks down and hormones called prostaglandins are released. These trigger the muscles of the uterus to contract and squeeze the lining out. The muscles are the same ones that push a baby out during childbirth, so they are very strong. Some women may have higher levels of prostaglandins and this is thought to be what causes painful muscle spasms called cramps.
The contents of this Web site are for informational purposes only and are not intended to be used for medical advice. You should consult your physician or health care provider on a regular basis. You should consult your physician immediately with any problem about which you are concerned.
B. What Sort Of Pain Is It?
You may feel no more than a passing discomfort from your period, or you could be doubled up by it. Usually the pain comes in cramp-like spasms. It could start in the lower abdomen, and may radiate up the spine and down the legs, or center in your lower back. If you get it really badly, you may feel dizzy or nauseous and get diarrhea or vomit. If this happens, you should go and see your doctor. Most women find the pain usually comes on a few hours before their periods start and begins to ease once the flow begins. But in a few, pain continues into the second and even the third day of their period.
C. What You Can Do for Yourself to Relieve the Pain
There are many ways to help relieve menstrual cramps. The trick is to find one that works for you. Lie down if possible at the first sign of pain, and place a warm heating pad on your abdomen. A relaxing, warm bath may also help. Seek advice from your pharmacist about suitable painkillers. Over-the-counter medications may be very helpful. For maximum relief, take painkillers before the pain gets too bad.
Massage can ease menstrual cramps. Gently rub your abdomen, or ask your partner to massage your back. Exercise routines, practiced throughout your cycle, but particularly a few days before the onset of your period may help to reduce pain by lowering your levels of prostaglandins. Exercise also helps to keep the blood flowing in your pelvis, easing that heavy, bloated feeling. Workouts that stretch your body-cycling with your legs up in the air, for example-are best.
D.What Your Doctor Can Do for You
Hormone treatments: Women who do not ovulate (that is produce a mature egg each month), will rarely have menstrual cramps. If, like most women, you do ovulate; your doctor may prescribe a hormone treatment to stop ovulation. The birth control pill is often used for this purpose.
Anti-prostaglandins: These are drugs that reduce the effect of prostaglandins and your doctor may prescribe them for you.
Surgery: In the past, many women with menstrual problems had an operation known as a D & C (dilation and curettage) to remove some of the lining of the uterus. This particular operation is rarely performed today but when a woman’s periods are very heavy as well as painful, her doctor may recommend its modern equivalent, endometrial ablation, which involves treatment with a laser.
E.Could It Be Something Else?
Menstrual cramps are sometimes caused, or made worse, by other conditions. This is known as secondary dysmenorrhea. If you suddenly start to experience more pain than usual or notice a change in your periods, you should contact your doctor. Older women in particular should consult their doctors if their pain does not respond to treatment.
Endometriosis occurs when cells from the uterine lining escape into other areas of the body where they cause irritation and pain.
Symptoms: Sharp abdominal pains as well as menstrual cramps; painful sexual intercourse.
Treatment: Hormone treatment is usual although your doctor may recommend surgery in severe cases.
Fibroids are non-cancerous growths inside the uterus.
Symptoms: Dull pain in the abdomen; swollen stomach; heavy and painful periods.
Treatment: Depends on where the fibroids are and how big they are. Sometimes none is needed. Fibroids grow in response to the hormone estrogen, and when this hormone decreases after menopause, the fibroids often shrink and practically disappear. Removal of the fibroids or a hysterectomy (surgical removal of the uterus) may be considered if the symptoms are severe.
Pelvic Inflammatory Disease (PID)
Pelvic Inflammatory Disease (PID) refers to long-term inflammation of any of the pelvic organs, usually caused by infection.
Symptoms: Painful intercourse; foul-smelling vaginal discharge; heavy and painful periods.
Treatment: Usually treated with antibiotics.
It is not possible for you to diagnose conditions like these yourself, so see your doctor if you have any of the symptoms. You could be referred to a hospital for a laparoscopy. This involves making a small incision in the abdomen and passing a tiny camera through it that is attached to a viewing tube. The doctor can then look around the pelvis to see what, if anything, is wrong.
Middle pain is experienced by some women about half-way through their menstrual cycle-usually 12-16 days after a period. The pain is one-sided and sharp, low down in the abdomen. It may last just a few minutes, or rarely several hours. The pain is caused by the egg bursting out of the ovary. If necessary, a mild painkiller may help.
Many women experience irregular periods at some time in their lives. The exact causes of irregular periods can vary and are often quite normal. You are the best judge of what is normal for you. If you have a sudden change in the regularity of your periods, chart your symptoms and consult your doctor.
Lifecycle of Menstruation
A. Ovulation & Fertility
Without ovulation, there is no fertility. That’s why birth control is so effective. Most birth-control pills prevent ovulation-that’s how they work. But to fully understand the role ovulation plays in fertility, we must start with the basics.
B. Reproductive Anatomy: Internal Structure
We believe that knowledge is a powerful tool. By giving you the straight facts about your body, She Comfort hopes to help you make healthy choices about your body-and your life.In this section, you can find up-to-date and medically sound facts about the female reproductive system. Discover the parts of the reproductive system and how they work. Keep in mind that while almost every woman’s anatomy is basically the same, each person is also slightly different. Differences in size, color, and shape are completely normal. If you have concerns, contact your healthcare provider.
We will start with these internal organs:
The vagina, also known as the birth canal, leads to the internal reproductive system. It is a narrow tunnel that measures between three and five inches in length. The vaginal opening is called the introitus. The vagina is surrounded by muscle and supporting tissue that can expand enough to allow passage of a baby. Natural vaginal secretions provide lubrication and keep a healthy balance of bacteria in the vagina to resist infection.
A certain degree of vaginal discharge is normal, and may change in consistency depending on the hormones present at different stages of the menstrual cycle. For example, during mid-cycle (ovulation), when estrogen levels are high, the cervix produces a large amount of watery secretions that you may perceive as vaginal discharge.
Normally, it looks clear and stretchy, and feels slippery-like mucus. Nature’s aim during ovulation is to enhance reproduction: the mucus is abundant and slippery, giving sperm the best possible chance of surviving in the cervix. In contrast, cervical mucus becomes thicker or disappears entirely at other times of the menstrual cycle.
After menopause, and even the few years leading up to menopause and thereafter, vaginal discharge may decrease. This reduction in lubrication, which is caused by lower levels of estrogen, may cause dryness, irritation or even infection.
At the top of the vagina is the cervix, or the connection between the vagina and the uterus. The cervix itself is only about an inch in diameter, small, and pink. The opening to the cervix, called the os, is a very small hole in the middle of the cervix. After pregnancy, it appears as a 1/4-inch slit. The os opening is big enough to allow the flow of fluids, such as menstrual blood, from the uterus. During the labor of pregnancy, the os opens to nine-ten centimeters to allow delivery of the baby. In non-pregnant women, the os is only open a few millimeters. Cervical mucus acts as a barrier to bacteria by preventing bacteria from entering the uterus and the fallopian tubes.
Many women notice changes in the consistency of the cervical mucus during their cycle. It is often thin and mucus-like during ovulation when estrogen levels are high, and thicker and more sticky-or seemingly nonexistent-at any other time of the menstrual cycle.
The uterus is a rose-hued, pear-shaped, muscular organ that can expand and stretch enough to accommodate the development of a fetus. The inner lining of the uterus is called the endometrium, which is a lining made up of blood vessels, specialized glands, and supporting tissue. This is the part of the uterus that is shed during a period.
There are three openings to the uterus. The cervix, which is the lower part of the uterus that opens to the vagina, and each fallopian tube which enters the uterus towards the top, one on either side.
The main function of the uterus is to create a nurturing environment for the growing fetus. During pregnancy, this small mass of muscle starts out about the size of a pear, and grows to become the largest muscle in the body, larger even than thigh muscles.
During menstruation, the uterus may contract in response to a series of hormonal changes: the shedding endometrium releases prostaglandins, which trigger contractions. Furthermore, the decline in progesterone that occurs just prior to menses may also contribute to uterine contractions. During labor, uterine contractions thin the lower segment of the uterus and cervix, a process called effacement, and expand the cervical os to prepare for delivery of the baby (dilation). Uterine contractions also assist in the actual delivery of the baby.
At menopause, as estrogen levels fall off, the endometrial lining no longer sheds and menstruation comes to an end.
Besides the cervix, there are two other openings in the uterus leading to two fallopian tubes. These soft, limp tubes extend about five inches from the uterus to the ovaries. There are four components that make up the fallopian tubes. The first is the intramural component, which is the segment that goes through the uterine muscle. The second component is the isthmus, or the first part of the tube after exiting the uterus. The next component is the ampulla. This is where fertilization occurs. Finally, the fallopian tubes end at the fimbria, which are fringed and trumpet-shaped with minuscule feather-like tissue at the end which grasp eggs (ova) that are released from the ovaries.
From a reproductive standpoint, the fallopian tubes are designed to perform four related functions:
Connect the ovary and the uterus
Transport sperm in the right direction (from the fallopian tube toward the uterus)
Provide a meeting place where conception happens
Help propel the fertilized egg by producing gentle, continuous contractions that move the egg toward the uterus
The fallopian tubes lead to the ovaries which are oval-shaped organs that secrete hormones and house eggs, or ova. Measuring about an inch and a half wide and an inch long, the two ovaries sit on either side of the uterus, attached to the uterus by a ligament
The ovaries can be smooth, or during ovulation, they become marked by clusters of rounded bumps, or follicles, which house and nurture eggs. The number of eggs that are contained in the ovaries depends on the age of the woman. The highest number is actually found before a girl is born. While still in the mother’s womb, a 20-week-old female fetus has approximately seven million eggs. At birth, the number has decreased to two million. By the time a girl enters puberty, she has between 300,000 and 500,000 eggs. This decline in number is the process called atresia, a natural and continuous process that is uninterruptible. Only between four and five hundred will ripen into mature eggs during a lifetime.
During the first half of the menstrual cycle, the follicles are growing and secreting estrogen and the egg is undergoing the maturation process. The egg continues to grow until it is released from the follicle and picked up by the fimbria and transported to the fallopian tube. Meanwhile, the empty follicle cells coalesce into a yellow mass, called the corpus luteum, which secretes estrogen and progesterone.
Progesterone is produced to support the gestation (or nurturing) of an egg in the event that it is fertilized and implanted in the uterus. If pregnancy does not occur, the estrogen and progesterone secretion from the corpus luteum will cease 11-16 days after ovulation. Without the support of the hormones, the endometrium will shed. Over time, the corpus luteum becomes incorporated back into the ovarian tissue.
As menopause approaches, ovarian estrogen begins to decline. Estrogen levels become very low once there are no remaining follicles in the ovaries. Without ovarian production of estrogen and progesterone, the endometrium is not stimulated to grow and shed. This eventually leads to the end of menstruation.
The Ovarian Clock
Dr. Cristina Matera M.D. Our lives are composed of many stages, some of which are subtle or blurred transitions such as the passage from childhood, through adolescence and into adulthood. Others are defined by rather specific events, for example when the pre-school years are abruptly ended by the first day of school and when graduation catapults us into the responsibilities of employment and professionalism.
Many women also categorize their lives by their “gynecologic age” or reproductive capabilities. The profound transition from an asexual child, to an energetic young woman, a mother, and finally to a mature, experienced woman in the post-reproductive or menopausal years can be viewed as gradual, but is also punctuated by a distinct event-the first and the last period.
Unlike men, women receive an undeniable signal informing them of their fertility (their first menses) and are also given a “fixed dose” of fertility which begins declining in the mid-30s and completely ceases at menopause in the late 40s to early 50s. In addition, the female hormone, estrogen, is known not only to be crucial in reproduction, but also to protect women from certain ailments such as osteoporosis, and possibly heart disease and Alzheimer’s disease. In contrast, the high levels of testosterone found in men may actually predispose them to conditions such as heart disease and prostate cancer.
The changes in women’s bodies that accompany the transition from the pre- to post-reproductive years are governed by the normal development, function, and eventual senescence of the ovaries. Most people do not spend a lot of time dwelling on these small, walnut-sized organs that are so vital to our health, livelihood, and future generations. However, since the ovarian life cycle is such an important aspect of each and every woman’s life, it may be of interest to understand how the ovaries are formed in a female embryo and work in a female body.
Development: the formation of the ovary
The two major roles of the ovary are to produce a mature egg for ovulation each month and to secrete the reproductive hormones. The functional unit within the ovary is the follicle. This structure is composed of an egg and the cells that surround the egg which manufacture estrogen, progesterone, and testosterone (albeit in much smaller quantities than in men).
The formation of the ovary begins very early in a developing embryo during pregnancy. The precursor cells, eggs in women and sperm in men, referred to as germ cells, are actually first found outside of the embryo in a structure known as the yolk sac. And at five-six weeks of pregnancy, they migrate from the yolk sac into the area that will eventually become the gonad (the generic term for an ovary in a woman and a testicle in a man). If the germ cells do not successfully migrate and arrive to this region, an ovary or testicle will not develop and only scar tissue will form.
At six weeks of pregnancy, this gonad is considered “bipotential”, or can develop into either an ovary or a testicle. If that embryo has the genetic make-up of a boy (46, XY), the gonad will receive the necessary information to transform into testes. If the “testes determining factor” is lacking, as in a genetic female (46,XX), an ovary will develop instead. This process occurs between six-nine weeks of pregnancy.
One of the first signs that the gonad will be an ovary is the exponential increase in the number of eggs, which occurs as a result of the duplication of the chromosomal content and the subsequent division of one egg to make two eggs. By the fifth month of pregnancy the female fetus contains six-seven million eggs, the maximum number that will ever be reached. Equally astounding is that over the course of the next four months of the pregnancy there is such a rapid decline in the number of eggs that at birth only two million eggs remain.
Why and how a woman loses 80% of her initial endowment of eggs prior to even being born is not completely understood. The vast number of eggs are lost in a process called “atresia,” where the follicles enter a growth phase that is never ultimately completed. This results in the demise of the egg and the other cells of the follicle get reincorporated into the ovarian tissue. The process of atresia begins in the female embryo and continues uninterrupted throughout a woman’s lifetime, however, at no other time will it occur at such a rapid rate as prior to birth. For every one egg that is “lost” by ovulation, thousands are lost in the process of atresia.
This limited, or finite number, of eggs contrast sharply with what occurs in men, where sperm are constantly being regenerated. Although you will see waves of follicular growth in the ovary of the embryo, full maturation, ovulation, and significant estrogen production do not occur. The situation differs in male fetuses where large amounts of testosterone are produced and are critical for the development of normal male genital organs.
The ovary in childhood
Soon after birth, when the baby girl is separated from the placenta (the source of huge amounts of estrogen and progesterone), the circulating levels of these hormone abruptly plummet. This results in a rebound or burst of activity in the ovary with multiple follicular growth. Eventually and often by the first birthday, the ovaries enter a quiescent stage. Although continuing waves of follicular growth occur, all of these follicles are doomed to fail and undergo atresia. There is essentially no hormonal production from the ovaries in the childhood years.
When a young woman reaches puberty, only 300,000-500,000 eggs remain. In a woman’s lifetime, 400 to 500 eggs will be released from the ovary by ovulation. The subtle and perhaps not-so-subtle signs that herald the onset of puberty in girls are due to the rise in the production of estrogen and testosterone. Sexual hair growth (pubic and underarm) results from male hormone production from the ovaries and the adrenal glands (two small organs found above the kidneys). Estrogen is responsible for breast development and the rapid growth seen in early adolescence. The rising estrogen levels also stimulate the growth of the lining of t the uterus (the endometrium). The eventual sloughing of this lining is a woman’s first period. By the time that a woman begins to menstruate, she has practically completed the pubertal transition.
The reproductive years
Rarely does a young woman ovulate during the first few menstrual cycles. In fact the irregular menses in the first one-two years is typical until the ovulatory process is fully functional and mature. This maturation process occurs in a specific area of the brain ( the hypothalamus and the pituitary gland). Different hormones that are secreted from these glands stimulate the ovary and when the dialogue of the hypothamo-pituitary-ovarian axis is organized, regular and monthly periods will occur. As the follicle is growing and maturing in preparation for ovulation, an increasing amount of estrogen is being produced. Progesterone is only made after ovulation by the corpus luteum, the “ruptured follicle”.
If a woman does not become pregnant the corpus luteum will cease to function approximately two weeks after ovulation. The decline in estrogen and progesterone levels removes the support of the now thickened endometrium and it will be sloughed as a menstrual flow. If a woman does conceive, the pregnancy hormone, hCG, will urge the corpus luteum to remain alive and make the hormones that are necessary to sustain an early pregnancy.
For each follicle that eventually ovulates, close to 1,000 will have a limited but unsuccessful growth. The number of eggs that are lost per ovulatory cycle probably varies throughout a woman’s life, but is presumed to be accelerated in the 10-15 years that precede menopause. At this time, not only are the numbers rapidly dwindling, but there is also a decline in the quality of the follicles. Hormonal production is not as predictable and robust and the eggs are also known to contain changes in their genetic make-up.
The decline in the quantity and the quality of eggs during this time adequately explains the diminishing in fertility that is seen in women from age 35 and onward – the proverbial “biologic clock.” Even if a woman should conceive, her chances of having a miscarriage because of a baby with a resultant chromosomal abnormality increases greatly as she gets older.
Just as the early reproductive years are characterized by unpredictable menstruation, so are the years that precede the last menstrual period. Erratic follicular growth without ovulation occurs, but estrogen is still being made. When all of the follicles in the ovary have been depleted, estrogen production ceases and a woman now enters menopause. Nonetheless the ovary does continue to manufacture male hormones. Although it remains controversial, these hormones are considered to play a role in maintaining bone health, normal libido or sex drive, cognitive function, and overall sense of well-being.
Thus the story of the ovary begins way before a little girl is even born and ceases to function by approximately 50 years of age. This contrasts markedly from men who continue to have normal testosterone secretion and sperm production well into their 70s. The depletion of eggs may protect women from getting pregnant at a time when she may not have the energy or longevity to satisfactorily raise a child. Alternatively it places pressures on the modern 20th century woman who is trying to complete her education, establish a rewarding profession, become financially secure, and also have a happy and close-knit family.