Politics often interferes where it has no natural business, and
one of those places is the discussion among a teenager, her parents, and her
doctor or between a woman and her doctor about the best
choices for health. The hottest button politics is pushing right now
takes the form of a tiny hormone-containing pill known popularly as the birth
control pill or, simply, The Pill. This hormonal medication, when taken
correctly (same time every day, every day), does indeed prevent pregnancy. But
like just about any other medication, this one has multiple uses, the majority
of them unrelated to pregnancy prevention.
But let's start
with pregnancy prevention first and get it out of the way. When I used to ask
my students how these hormone pills work, they almost invariably answered,
"By making your body think it is pregnant." That's not correct. We
take advantage of our understanding of how our bodies regulate hormones not to
mimic pregnancy, exactly, but instead to flatten out what we usually talk about
as a hormone cycle.
The Menstrual Cycle
In a hormonally cycling girl or woman, the brain talks to the
ovaries and the ovaries send messages to the uterus and back to the brain. All
this chat takes place via chemicals called hormones. In human females, the
ovarian hormones are progesterone and estradiol, a type of
estrogen, and the brain hormones are luteinizing hormone
and follicle-stimulating
hormone. The levels of these four hormones drive what we think of as
the menstrual cycle, which exists to prepare an egg for fertilization and to
make the uterine lining ready to receive a fertilized egg, should it arrive.
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Fig. 1. Female reproductive anatomy. Credit: Jeanne Garbarino. |
In the theoretical
28-day cycle, fertilization (fusion of sperm and egg), if it occurs, will happen about 14 days in, timed
with ovulation, or release of
the egg from the ovary into the Fallopian
tube or oviduct (see video--watch for the tiny egg--and Figure
1). The fertilized egg will immediately start dividing, and a ball of cells
(called a blastocyst)
that ultimately develops is expected to arrive at the uterus a few days later.
If the ball of cells shows up and implants in the uterine wall, the
ovary continues producing progesterone to keep that fluffy, welcoming uterine
lining in place. If nothing shows up, the ovaries drop output of estradiol and
progesterone so that the uterus releases its lining of cells (which girls and
women recognize as their “period”), and the cycle starts all over again.
A typical cycle
The typical cycle (which almost no girl or woman seems to have)
begins on day 1 when a girl or woman starts her "period." This
bleeding is the shedding of
the uterine lining, a letting go of tissue because the ovaries have bottomed out production of the hormones that keep the tissue intact. During this time, the brain
and ovaries are in communication. In the first two weeks of the cycle, called
the “follicular phase” (see Figure 2), an ovary has the job of promoting an egg
to mature. The egg is protected inside a follicle that spends about 14 days
reaching maturity. During this time, the ovary produces estrogen at increasing
levels, which causes thickening of the uterine lining, until the estradiol hits a peak about
midway through the cycle. This spike sends a hormone signal to the brain, which
responds with a hormone spike of its own.
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Fig. 2. Top: Day of cycle and phases. Second row: Body temperature (at waking) through cycle. Third row: Hormones and their levels. Fourth row: What the ovaries are doing. Fifth row: What the uterus is doing. Via Wikimedia Commons. |
In the figure, you can see this spike as the red line indicating
luteinizing hormone. A smaller spike of follicle-stimulating hormone (blue
line), also from the brain, occurs simultaneously. These two hormones along
with the estradiol peak result in the follicle expelling the egg from the ovary
into the Fallopian tube, or oviduct (Figure 3, step 4). That’s ovulation.
Fun fact: Right when the estrogen spikes, a woman’s body
temperature will typically drop a bit (see “Basal body temperature” in the
figure), so many women have used temperature
monitoring to know that ovulation is happening. Some women also may
experience a phenomenon called mittelschmerz,
a pain sensation on the side where ovulation is occurring; ovaries trade off follicle
duties with each cycle.
The window of time for a sperm to meet the egg is usually very
short, about a day. Meanwhile, as the purple line in the “hormone level”
section of Figure 2 shows, the ovary in question immediately begins pumping out
progesterone, which maintains that proliferated uterine lining should a ball of dividing cells show up.
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Fig. 3. Follicle cycle in the ovary. Steps 1-3, follicular phase, during which the follicle matures with the egg inside. Step 4: Ovulation, followed by the luteal phase. Step 5: Corpus luteum (yellow body) releases progesterone. Step 6: corpus luteum degrades if no implantation in uterus occurs. Via Wikimedia Commons. |
The structure in the ovary responsible for this phase, the luteal
phase, is the corpus luteum (“yellow body”; see Figure 3, step 5), which puts
out progesterone for a couple of weeks after ovulation to keep the uterine
lining in place. If nothing implants, the corpus luteum degenerates (Figure 3,
step 6). If implantation takes place, this structure will (should) instead continue producing
progesterone through the early weeks of pregnancy to ensure that the lining
doesn’t shed.
How do hormones in a pill
stop all of this?
The hormones from the brain--luteinizing hormone and
follicle-stimulating hormone-- spike because the brain gets signals from the
ovarian hormones. When a girl or woman takes the pills, which
contain synthetics of ovarian hormones, the hormone dose doesn’t peak that way.
Instead, the pills expose the girl or woman to a flat daily dose of hormones
(synthetic estradiol and synthetic progesterone) or hormone (synthetic
progesterone only). Without these peaks (and valleys), the brain doesn’t release the hormones that
trigger follicle maturation or ovulation. Without follicle maturation and
ovulation, no egg will be present for fertilization.
![]() |
Assorted hormonal pills. Via Wikimedia Commons. |
Most prescriptions of hormone pills are for packets of 28 pills.
Typically, seven of these pills--sometimes fewer--are “dummy pills.” During the
time a woman takes these dummy pills, her body shows the signs of withdrawal from the
hormones, usually as a fairly light bleeding for those days, known as “withdrawal
bleeding.” With the lowest-dose pills, the uterine lining may proliferate very little, so that this bleeding can be quite light compared to what a
woman might experience under natural hormone influences.
How important are hormonal
interventions for birth control?
Every woman has a story to tell, and the stories about the
importance of hormonal birth control are legion. My personal story is this: I
have three children. With our last son, I had two transient
ischemic attacks at the end of the pregnancy, tiny strokes resulting
from high blood pressure in the pregnancy. I had to undergo an immediate
induction. This was the second time I’d had this condition, called pre-eclampsia,
having also had this with our first son. My OB-GYN told me under no uncertain
terms that I could not--should not--get pregnant again, as a pregnancy could be
life threatening.
But I’m married, happily. As my sister puts it, my husband and I “like
each other.” We had to have a failsafe method of ensuring that I wouldn’t
become pregnant and endanger my life. For several years, hormonal medication
made that possible. After I began having cluster headaches and high blood
pressure on this medication in my forties, my OB-GYN and I talked about
options, and we ultimately turned to surgery to prevent pregnancy.
But surgery is almost always not reversible. For a younger woman, it’s not the
temporary option that hormonal pills provide. Hormonal interventions also are
available in other forms, including as a vaginal ring, intrauterine
device (some are hormonal), and implants,
all reversible.
One of the most important things a society can do for its own health is to ensure that women in
that society have as much control as possible over their reproduction. Thanks
to hormonal interventions, although I’ve been capable of childbearing for 30
years, I’ve had only three children in that time. The ability to control my
childbearing has meant I’ve been able to focus on being the best woman, mother,
friend, and partner I can be, not only for myself and my family, but as a
contributor to society, as well.
What are other uses of
hormonal interventions?
Heavy,
painful, or irregular periods. Did you read that part about how flat hormone inputs can mean
less build up of the uterine lining and thus less bleeding and a shorter
period? Many girls and women who lack hormonal interventions experience
bleeding so heavy that they become anemic. This kind of bleeding can take a
girl or woman out of commission for days at a time, in addition to threatening
her health. Pain and irregular bleeding also are disabling and negatively affect quality of life on a frequent basis. Taking a single pill each day can make it all better.
Unfortunately, the current political climate can take this situation--especially for teenage girls--and cast it as a personal moral failing with implications that a girl who takes hormonal medications is a "slut," rather than the real fact that this hormonal intervention is literally maintaining the regularity of her health.
Unfortunately, the current political climate can take this situation--especially for teenage girls--and cast it as a personal moral failing with implications that a girl who takes hormonal medications is a "slut," rather than the real fact that this hormonal intervention is literally maintaining the regularity of her health.
For some context, imagine that a whenever a boy or man produced
sperm, it was painful or caused extensive blood loss that resulted in anemia.
Would there be any issues raised with providing a medication that successfully
addressed this problem?
Polycystic
ovarian syndrome.
This syndrome is, at its core, an imbalance of the ovarian hormones that is associated with all kinds of problems, from acne to infertility to overweight to uterine
cancer. Guess what balances those hormones back out? Yes. Hormonal medication,
otherwise known as The Pill.
Again, for some context, imagine that this syndrome affected
testes instead of ovaries, and caused boys and men to become infertile,
experience extreme pain in the testes, gain weight, be at risk for diabetes, and
lose their hair. Would there be an issue with providing appropriate hormonal
medication to address this problem?
Acne. I had a friend in high school who was on
hormonal medication, not because she was sexually active (she was not) but
because she struggled for years with acne. This is an FDA-approved use of this
medication.
Are there health benefits of
hormonal interventions?
In a word, yes. They can protect against certain
cancers, including ovarian and endometrial, or uterine, cancer. Women
die from these cancers, and this protection is not negligible. They may also
help protect against osteoporosis, or bone loss. In cases like mine, they
protect against a potentially life-threatening pregnancy.
Speaking of pregnancy, access to contraception is “the only
reliable way” to reduce unwanted
pregnancies and abortion rates [PDF]. Pregnancy itself is far
more threatening to a girl’s (in particular) or woman’s health than
hormonal contraception.
Are there health risks with
hormonal interventions?
Yes. No medical intervention is without risk. In the case of
hormonal interventions, lifestyle habits such as smoking can enhance risk for high
blood pressure and blood clots. Age can be a factor, although--as I can
attest--women no longer have to stop taking hormonal interventions after age 35
as long as they are nonsmokers and blood pressure is normal. These interventions
have been associated with a decrease in some cancers, as I’ve noted, but also
with an increase in others, such as liver cancer, over the long term. The
effect on breast cancer risk is mixed and may have to do with how long taking
the medication delays childbearing. ETA: PLoS Medicine just published a paper (open access) addressing the effects of hormonal interventions on cancer risk.
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By Emily Willingham, DXS Managing Editor
Opinions expressed in this piece are my own and do not necessarily reflect the opinions of all DXS editors or contributors.
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