Chapter 1
Basic Female Anatomy and
How It All Works
In this chapter, the basic female anatomy, which is crucial for
childbearing, will be discussed in more detail in order to build a
foundation on which to base all of our further discussions. So you will
be able to refer back to this chapter if you need to later in the book.
The changes that must occur at puberty set the stage, so to speak, for
the drama of life to unfold. These changes usually occur around the
age of twelve; however, they may begin as early as age eight or nine or
as late as age fifteen or sixteen (normally). What changes are these, you
may ask. Specifically, I am referring to the increase in height (a growth
spurt), the increase in breast size, the development of both axillary and
pubic hair, and last but not least, the onset of the menses (the monthly
bleeding that occurs and that is known as the period). When these
changes occur before the age of eight or after the age of sixteen, there is
10 Dr. Rachel Donaldson
usually something abnormal in that person’s development, and the child
should be seen by a medical doctor to evaluate this further. Sometimes
the abnormality can be detected through certain blood tests. Now you
may think that when the periods finally start, the whole process is finished
and that you can sit back and relax. Not so. This process may actually take
several years to complete before a regular menstrual pattern could be
established. The reason that this takes time is that the brain (particularly
certain structures within the brain known as the hypothalamus and the
pituitary gland) needs time to mature as well. The hypothalamus and
the pituitary gland are structures located almost centrally in the brain.
If you were to draw a line across from one ear to the other and from
the space between the eyebrows to the back of the head, the pituitary
gland would be located where those lines intersect or cross. The pituitary
gland is a small structure about the size of medium-sized grape, and the
hypothalamus is the area right above the pituitary gland. See figure 1.
11 A Doctor’s Guide To Pregnancy
The hypothalamus and the pituitary gland produce hormones.
Hormones are special chemicals made by one part of the body that have
an effect on another part of the body. They are sort of like signals, or ways
that one part of the body can communicate with another part of the body.
The chemicals are released into the bloodstream and get to other parts
of the body through the bloodstream. These chemicals (hormones) then
produce certain effects on the other organs, glands, or body parts. To
be more specific, the hormones produced by the hypothalamus have an
effect on the pituitary gland, and the hormones produced by the pituitary
gland have their effects on several other glands in the body, including the
thyroid gland, the ovaries in women and the testes in men, the adrenal
gland, and the pigment-producing cells in the body. In addition, the
pituitary gland produces growth hormone (GH), which has its effect
on every cell in the body. The main hormone that we will be concerned
about that is produced by the hypothalamus is luteinizing hormonereleasing
hormone , or LHRH. It also produces oxytocin. The one we
will be primarily concerned with in this chapter is the LHRH. This is also
known as gonadotropin-releasing hormone or GnRH. LHRH/GnRH
is released into the bloodstream that bathes the hypothalamus and the
pituitary gland. In this case, the target gland (the pituitary gland) is very
close to the tissue that made the hormone. LHRH / GnRH stimulates the
pituitary gland to produce two more hormones—luteinizing hormone
(LH) and follicle-stimulating hormone (FSH)—both of which have a
large role to play in the normal function of the ovaries, which we will
describe in detail a little later. Suffice it to say that both hormones are
very important. Now the ovary is a long distance away from the pituitary
gland, so it receives these signals through the bloodstream. Other
hormones made by the pituitary gland include growth hormone (GH),
12 Dr. Rachel Donaldson
thyroid-stimulating hormone (TSH), prolactin , adrenocorticotropic
hormone (ACTH), and melanocyte-stimulating hormone (MSH). TSH
has its effects on the thyroid gland; prolactin has its effects on the breast
and is very important for breast-feeding. ACTH has its effect on the
adrenal glands , which are located on the top of each kidney, and MSH
has its effect on all the pigment-producing cells in the body. This is the
hormone that contributes to skin color. In fact, all of these hormones are
somewhat similar in chemical structure but different enough to be able to
do different things. And if one hormone is either deficient or present in
excess, then there are a lot of widespread effects. For example, if growth
hormone is deficient, then one’s stature is short (a dwarf), whereas if
growth hormone is present in excess, then one’s stature is tall (a giant).
Again, please refer to figure 1—a graphic view of the internal structures
of the brain and the hormones that are produced there.
Now, let us get back to our discussion of the normal developmental
changes that are happening in the body around puberty. It is during
this time that FSH and LH are being secreted by the pituitary gland in
a synchronized, cyclical, pulsatile fashion, and it isn’t until the pulses
develop a specific frequency and pattern that a regular menstrual cycle
begins—that is, assuming that all the other structures are present and
functioning as well. The ovary , the uterus, the cervix, and the vagina
have to be normal in order to have a predictable cycling period. The
percentage of body fat and the total weight of the individual have a role
in the pattern of the FSH and the LH that are released. Very slender,
underweight girls usually tend to start their periods later than overweight
girls. Disorders of the menstrual cycle (for example, not starting a period
at all) could be the result of a deficiency or failure of development of any
of these organs, whether it be the hypothalamus, the pituitary gland, the
13 A Doctor’s Guide To Pregnancy
ovary, the uterus, the cervix, or the vagina. If you will look at figure 2, you
will see the normal relationship of the female organs to each other.
Assuming that there are both normal hormonal secretions and normal
structures, the following scenario takes place. The ovary responds to the
FSH and LH signals by selecting a follicle (egg). There are thousands of
eggs in the ovary, all surrounded by some cells, and these are known as
follicles. The growth of this follicle is stimulated by these two hormones,
and as it grows, it starts to make some hormones of its own—particularly
estrogen; and this is released into the bloodstream where it has its effects
not only on the uterus where the lining of the uterus is built up, but so
on the skin, the bones, the brain, and the breasts. Estrogen stimulates
the growth of the breasts, and it increases the strength of the bones.
Once the estrogen level reaches a certain level, then the pituitary gland
sends out a surge of LH, which then stimulates the follicle to release
the egg. This is known as ovulation. The egg that is released from the
follicle is picked up by the fallopian tube (usually on the same side as
where the egg was released) and carried to the uterus. After the egg is
released, there is a switch in hormone production by the follicle. It is
14 Dr. Rachel Donaldson
also now called a corpus luteum instead of a follicle, and it produces
progesterone instead. This hormone is also extremely necessary to
produce the desired effect on the lining of the uterus to prepare it for
a possible pregnancy. Progesterone causes the lining of the uterus to
become thick and lush, loaded with blood vessels. It also helps with bone
strength, and metabolism, so that a developing baby can obtain all the
nutrients and energy that it needs. Progesterone helps to release these
stored nutrients and energy from the cells of the mother’s body. If the
egg that is released is not fertilized, and the person does not become
pregnant, then the lining of the uterus will shed. This shedding of the
lining—or bleeding—is called the menses or the period. It normally
occurs about 14 days after ovulation occurs. See figure 3.
15 A Doctor’s Guide To Pregnancy
This whole process will repeat itself month after month until
the majority of the eggs are used up, which is when menopause will
begin. Menopause will be discussed in another book.
The ovaries also produce many other hormones, one of which is
testosterone (traditionally known as the male hormone). This is actually
a very important hormone as it is what stimulates growth of the body and
bones, development of the pubic and axillary hair, and plays a crucial
role in your sex drive. The majority of this hormone is bound up in the
blood by certain proteins called sex-hormone-binding globulins, but a
small percentage that is not bound up is free to act at the tissue level and
can stimulate more hair growth than desired (especially in places like
the upper lip or chin), or even have an effect on the predictability of the
menstrual cycle. If the percentage of the free testosterone is higher than
normal, or if there are higher levels of some of the hormones that are
made in the process of making testosterone, then there can be irregular
menstrual cycle, more facial hair and acne and weight gain as a result.
The actual structures that are essential to normal childbearing
include at least one functioning ovary, at least one functioning
fallopian tube, a normally shaped uterus, and a patent (or open)
cervix and vagina. It only follows that if any of these structures are
missing or abnormal, then pregnancy is almost impossible—except
in situations of in vitro fertilization where the fallopian tube is
bypassed because it is either nonfunctioning or absent. In this
particular situation, the egg is harvested through surgical means
(after stimulating multiple eggs to maturation by certain drugs), and
then the egg is fertilized outside the body in a test tube or special
container filled with essential nutrients and sperm. The fertilized
egg, now called a zygote, is then reimplanted in the uterus at the
16 Dr. Rachel Donaldson
appropriate phase of the cycle following ovulation, usually the sixth or
seventh day—about one week before you would be due for a period.
Of course, this is a more expensive way to get pregnant, but successes
have occurred in rising numbers. However, there is a much greater
risk of twins, triplets, or quadruplets with this method. This is one
instance where medical science has been able to offer the possibility
of pregnancy to women who, through some misfortune, surgical
procedure, or infection, have lost the function of the fallopian
tubes. There are many other examples of where medical science has
excelled, but these examples are not the focus of this discussion.
At birth, there are about two million eggs in the ovary, and this
number drops quickly to about four hundred thousand by the age
of about eight years. The highest quantity of eggs are found in a five month
fetus, and at that time there are almost seven million eggs.1
Now you may wonder how, if ovulation is occurring so regularly, you can
be sure that it has occurred. How can you detect whether it has occurred?
And it is good that you have asked these questions. Some women can
detect ovulation by the occurrence of significant pain that is usually one sided,
and that lasts about 24 to 48 hours almost halfway between one
period and the next. This pain has been commonly called Mittelschmertz,
a German word that means pain in the middle (meaning middle of the
cycle). Another way you can detect ovulation is to take your temperature
first thing in the morning upon awakening—before arising, brushing
your teeth, emptying your bladder, etc. Of course, if you have to work
during the night, as some people do, then the temperature is taken when
you wake up after several hours of rest. The time of the day is really not
critical. It does help to have a special thermometer to do this, called a basal
body thermometer, which usually gives a digital readout. The mercury
17 A Doctor’s Guide To Pregnancy
thermometers are difficult to read, and small temperature changes may
not be easily noticed. When there is a temperature fall, followed by a
larger temperature rise-to a higher temperature than initially obtained in
the first half of the cycle—then this is usually indicative that ovulation has
occurred. The temperature should then stay up until the menses begins.
As I mentioned before, this is typically 14 days. The phase of time from
ovulation to when the menses starts tends to be a very consistent number,
and the time frame from the onset of the period to ovulation is highly
variable, ranging anywhere from 8 to 20 days in the normal situation.2
See figure 4, a typical basal body temperature chart.
Ovulation test kits
Other ways to confirm ovulation nowadays include ovulation kits,
which usually involve testing your urine in the morning for the presence
18 Dr. Rachel Donaldson
of LH, the hormone that peaks suddenly prior to ovulation. These kits
are more helpful in the situation where it is difficult to detect ovulation
by other measures. There are several different ovulation kits on the
market, and these are First Response Ovulation Predictor Test (about
$19.49), Clear Blue Easy Ovulation Predictor (about $28.99), and Answer
Daily Ovulation Tracker Kit (about $19.99), and Ovulation Scope (about
$19.99). First Response has test strips for 7 days, and it involves placing
an absorbent tip of the test strip in the urine stream for 5 seconds. You
read the test in 5 minutes. Two purple lines indicate that ovulation has
occurred. Clear Blue Easy also has test strips for 7 days, and you hold
the test strip in the urine stream for 5-7 seconds and read the test in 3
minutes. A smiley face indicates an LH surge has occurred, confirming
ovulation. With the Answer Daily Ovulation Tracker, you collect the urine
sample and place the test strip tip in the urine for 10 seconds. Two dark
lines indicate ovulation has occurred, and one light line and one dark
line indicate that ovulation has not occurred. All these tests should be
done on urine that is just produced (rather than on urine that has been
sitting out for a while). The final ovulation kit called Ovulation Scope can
be reused multiple times and involves a saliva test. There is an eyepiece,
and there is a slide. You place a generous amount of saliva on the slide
and let it dry for 10 minutes. You then replace the eyepiece and look into
it while turning on the light source. This one is moderately complex, but
the answer is evident when you look into the eyepiece.
Pregnancy test kits.
There are many pregnancy test kits on the market today. Generally
it is better to use fresh urine for the test, but if the urine has been
19 A Doctor’s Guide To Pregnancy
refrigerated to run the test later in the day, then the urine does need
to sit out temporarily until the urine is at room temperature. EPT is
about 99% accurate and involves placing the absorbent test strip in
the urine for 5 seconds, and then you read the results in 2 minutes.
There is a plus/minus (+/-) indicator, and the test kit costs about
$15.69. EPT Certainty involves placing the test strip tip in the urine
stream for 5-7 seconds and then reading the results within 3 minutes.
This is also 99% accurate and results are read as pregnant or not
pregnant. This test costs around $20.00, but there are 2 tests in the
kit. Then there is First Response Pregnancy Kit. This also contains 2
test strips. You place the test strip in the urine stream for 5 seconds
and read it in 5 minutes. There are 2 solid lines for pregnant and only
1 solid line for not pregnant. This one costs around $10.00. Clear
Blue Easy Pregnancy Test involves placing the absorbent tip in the
urine stream for 5 seconds and then reading the test in 3 minutes.
This is also about 99% accurate and costs around $12.50. This shows
up as pregnant or not pregnant. Then there is Fact Plus Pregnancy
Test. This one costs about $10.00 and contains 2 tests. You place
the absorbent tip in the urine stream for 5 seconds and then read
the test in 2 minutes. The answer is either + or -. In addition, many
stores carry their own brand of the pregnancy test, which usually
runs a little cheaper than brand names. It is better to run the test
on the first-morning urine sample, but not absolutely critical to do
this. Over the years, the pregnancy and ovulation kits have become
significantly simpler to use.
Now there is also a way to test the partner at home to see if he has
enough sperm. The test is called Baby Start, and there are 2 tests in
20 Dr. Rachel Donaldson
the kit. You collect the semen sample in a special cup and wait 15
minutes. Then you add the semen and the solution in the kit to the
cassette in the kit and read the results. This costs around $30.00.
Internal female anatomy
The ovary normally measures about 2 centimeters by about 4
centimeters in size, (about 3/4 by 1 ½ inches), and usually there
are two ovaries. However, you need at least one functioning ovary in
order to get pregnant. In the normal situation, ovulation will alternate
between one ovary one month and the other ovary the next month.
Small cysts in the range of up to two centimeters (a little less than one
inch in diameter) can occur with ovulation, and these tend to resolve
spontaneously. As I mentioned previously, some individuals can tell
when ovulation occurs as the cysts can cause pain (Mittleschmertz)
when they rupture. Cysts larger than 2-3 centimeters could be of
concern and so should be followed closely by your doctor. Occasionally
surgery may be necessary to either drain or remove the cyst, particularly
if they get over 6 centimeters (or about 3 inches) in diameter. Most of
the time, the small cysts tend to disappear on their own over time.
Now, to place a little more attention to the fallopian tubes, there
are normally two of these as well—one located on the right, and one
located on the left. The fallopian tubes are essentially hollow tubes
that are connected to the uterus. However, these hollow tubes are not
shaped like a metal pipe; they are flexible instead and are lined by a
convoluted layer of cells that have little hairs (called cilia) on them.
These little cilia wave back and forth in a coordinated pattern and thus
facilitate the passage of the egg through the tube to the uterus. (Please
refer to fi gure 5.) The inner diameter of this passageway is variable,
21 A Doctor’s Guide To Pregnancy
with the largest diameter located at the end of the tube near the ovary
where the egg is to be picked up. The end of the tube has projections
on it called fimbria. The fimbria are fingerlike in appearance, and
they are positioned closely to the ovary in order to collect the egg once
ovulation has occurred. The narrowest diameter is at the junction of
the tube to the uterus, but there is a connection between the tube, the
uterus, and the cervix, thus leading to the vagina and the outside.
Next, we will look more closely at the uterus. This structure is
composed of smooth muscle and is pear-shaped. It is about the size of a
medium plum in the never-been-pregnant (nulliparous) condition. It is
about the size of a large pear in the previously pregnant (multiparous)
condition. The uterus is lined by several layers of cells which regenerate
and slough off with each menses, only to regenerate again in the
next cycle in response to the hormones produced by the ovary. In
actuality, almost the whole layer sloughs off, only a small amount
remains behind to be the layer that will rebuild itself. In other words,
this is a repeating, cyclical process, and the changes that occur in the
lining of the uterus occur with the sole purpose of preparing it for
22 Dr. Rachel Donaldson
a possible pregnancy. If a pregnancy occurs, then the lining—which
has an extensive network of blood vessels—provides the nutrients that
facilitate growth of an early fetus (or embryo as it is called in this early
phase). The uterus also grows in size to accommodate the enlarging
fetus, placenta, and the amniotic fluid. If pregnancy does not occur,
then the lining degenerates and sloughs off as the period.
The cervix also plays an important role here as it acts as the
gatekeeper to the uterus. It produces a thick mucus that essentially
blocks the cervical canal, except at midcycle (or at ovulation).
At this time, there are changes in the quality of the mucus that
actually promote the passage of the sperm through it into the
uterus. This is due to the action of estrogen on the cervical gland
cells. The mucus produced by the glands becomes very stringy,
runny, and clear. At other times, the mucus is usually thick, sticky,
and tenacious. Some women have used the quality of the cervical
mucus to detect whether ovulation has occurred or as an aid in
family planning; for example, either avoiding intercourse or using
additional protection for several days before, during, and after
ovulation. In some situations, the cervix does not produce enough
mucus and in other situations—too much. These conditions could
potentially be a problem when you are trying to get pregnant. Also,
the cervix can harbor infections like chlamydia and gonorrhea.
Both of these are considered to be sexually transmissible diseases
(STD), which can lead to not only increased discharge, but also
to pelvic pain and infertility (by destroying the normal layer
of hair cells in the fallopian tube, and by causing blockage in
the fallopian tube). If these are diagnosed by your health care
provider, they need to be treated right away to reduce the chance
23 A Doctor’s Guide To Pregnancy
that the infection will cause damage to the tubes. Another STD
that commonly affects the cervix is ureaplasma and mycoplasma.
These are two bacterial infections that are commonly associated
with infertility. These normally will respond to antibiotics given to
both partners. Another STD is the human papilloma virus (HPV).
This is a viral infection that is very common in today’s society and is
transmitted through sexual contact. This infection does not usually
have any symptoms except when it occurs on the outside, and then
it causes itchy, wartlike bumps. On the cervix, this infection can
possibly lead to precancerous changes or even cancer of the cervix,
so it is very important to keep up with regular Pap smears for this
reason. A Pap smear is a screening test for cervical cancer that is
done in your doctor’s office or your nearest public health clinic.
The best prevention against sexually transmissible diseases is to
avoid sex altogether until you are in a monogamous (only one
partner) relationship, and you stay in a monogamous relationship.
Having sex with more than one partner not only increases your
risks of STD (including AIDS) and infertility, but also of cervical
cancer at an early age. However, there is now a vaccine available to
prevent the development of cervical cancer. This vaccine protects
against 4 of the more common HPV subtypes—6, 11, 16, and
18. The first 2 subtypes are associated with genital warts and the
second 2 subtypes are associated with cervical cancer. Ideally the
vaccine should be given before you initiate sexual activity, and it
is recommended for all women between the ages of 11 and 26.
So far it requires a series of 3 shots, given initially, and then the
second shot is 2 months after the first shot, and the third shot is
6 months after the first shot.
24 Dr. Rachel Donaldson
Even if you get the HPV vaccine, it is still important to get Pap
smears regularly, as this has been the single most important screening
tool that has helped to decrease the occurrence of cervical cancer.
The final structure of singular importance to the ability to get
pregnant is a functioning vagina. As you may already know, the
vagina is a long tubular structure that connects the outside of the
body to the inner structures—cervix, uterus, etc. The vagina is very
pliable and very stretchable, as it is partly composed of muscle,
and it is covered by a smooth surface. There is connective tissue
surrounding the vagina which contributes to its ability to stretch—
especially at the time of childbirth. The total length of the vagina
varies between six to ten centimeters.3 The vagina also produces a
small amount of secretions, but some of the secretions are a direct
result of secretions produced by the cervix and uterus. Normally
there are no glands along the length of the vagina; however, there
are several glands located around the vaginal opening, and these
glands produce both fluid and mucus that is released especially at
the time of sexual arousal.4 This mucus then lubricates the vagina
and decreases the discomfort that can be associated with dryness
at the time of sexual intercourse.
External female anatomy
External structures that are a part of the normal female anatomy
but that are not absolutely necessary for pregnancy include the labia,
or lips, clitoris, and urethra. The labia are further divided between
the labia majora (or larger, longer structures that are padded with fat
and covered with hair, and the labia minora, which are narrow folds
of tissue that are not covered with hair. There are usually two of each
25 A Doctor’s Guide To Pregnancy
these, one of each on each side. The labia minora meet centrally at
the top to form the clitoris, a highly sensitive organ whose primary
purpose is for sexual arousal. Its counterpart in the male is the end
of the penis. The urethra is the outlet for the bladder which stores
urine, and the urethral opening is located right below the clitoris
and above the vaginal opening.
As you can see from this general outline and discussion, what
seems to be a natural process and aspect of life can actually be a
very complicated process. Any step in the entire scheme of things
may not function normally and could result in an inability to get
pregnant or in complications during pregnancy. Considering the
sophistication and complexity of this system, it is actually amazing
that so many women do get pregnant. About 80 to 85% of women
that engage in unprotected intercourse will get pregnant within a
year. The 15 to 25% of couples that do not get pregnant within a
year of unprotected intercourse are diagnosed as being “infertile.”
Each individual situation has to be analyzed separately. The causes
of infertility are multiple. In fact, in the couples that are considered
to be infertile, 40% of the time there is a female factor, 40% of
the time there is a male factor.5 Ten percent of the time there is a
combination of minor problems on each side, and in the final 10%
of time, an actual reason or cause is never determined.
Male Factors
Firstly, in the male factor, problems such as infection in the genital
tract have to be considered. Inadequate sperm counts also play a
role. Now what is considered inadequate? Obviously there are men
that do not have any sperm in their semen—either naturally or as a
26 Dr. Rachel Donaldson
result of surgery (i.e., vasectomy or sterilization), or perhaps there
are sperm but just not enough of them. Levels lower than 20 million
are associated with a much higher rate of infertility. Other factors
include decreased motility of the sperm or inadequate quantities
of semen, to name a few.6 There are ways to correct or compensate
for some of these problems, but in order to find out what could be
the problem, your partner will have to be checked. A sperm count
is the most important test for the male factor in assessing infertility.
Secondly, a physical examination is also essential.
Female Factors
Of female factors, tubal blockage, infrequent ovulation, inadequate
progesterone levels, or cervical factors are the most common
contributing elements to infertility. Immune factors can also play a
role. You need to develop an open line of communication with your
doctor to find out which of these problems may be present and if a
specific treatment would help to correct or compensate sufficiently
to increase your chances of getting pregnant. Unfortunately the
testing usually is very time-consuming, and certain tests can only
be done at a particular time during the month, and so it tends to
be discouraging. There are certain abnormalities that cannot be
corrected, for example, if you were born without a uterus. In this
situation, you would have to settle for adoption or being childless.
But speaking from experience, miracles do happen, and you should
not give up hope for a planned pregnancy (provided you have all the
appropriate anatomy), if you are seriously pursuing it. In fact, the
aid of specialists in infertility may be required in certain instances to
facilitate the diagnosis and correction of specific problems.
27 A Doctor’s Guide To Pregnancy
Notes
1. J. A. Pritchard, P. C. MacDonald, N. F. Gant. Williams Obstetrics, 17th
ed. (Appleton-Century-Crofts), 33.
2. Ibid., 43.
3. Ibid., 12.
4. Ibid., 10.
5. ACOG Technical Bulletin, “Male Infertility,” June 1990.