- [Voiceover] In ancient Egypt, women
who questioned whether they were pregnant or not
were told to urinate on bags of wheat and barely
over the course of several days.
And if the wheat sprouted, the woman was having a girl
and if the barley sprouted, she was having a boy,
and if neither sprouted, she wasn't pregnant.
So I guess you could say that the question of
"Am I pregnant?" is as old as time.
And the craziest thing about that story
is that they tested it in the 60s and they found out
that it worked 70% of the time.
Okay, so how do we tell if a woman
is pregnant in the age of modern medicine,
so today?
Well, there are a few different signs of pregnancy and
the signs of pregnancy are divided
into three different groups.
So first, there are the presumptive,
the presumptive,
the presumptive signs of pregnancy
and these are changes that are experienced
by the woman that make her think
that she might be pregnant.
And then the second group of signs
are the probable signs.
The probable, probable signs of pregnancy,
which are changes that are seen on physical exam
that make the examiner suspect that the woman
might be pregnant.
And then finally, there are the
positive signs of pregnancy.
The positive signs of pregnancy, or signs that
can only and only be explained by pregnancy.
Alright, so let's start with the presumptive signs.
So we're talking about signs that make the woman
think she's pregnant.
And the number one sign has to be a missed period.
And the medical term for that is amenorrhea.
The medical term for a missed period is amenorrhea.
And if you've heard enough of these Latin words,
you may have picked up that putting an A
in front of a word means lack of.
So this is lack of menses.
And you know I think it's really important
that you understand why the period is missed in pregnancy.
So really briefly, over here you have a uterus
and the uterus has layers.
but the inner most layer, the endometrium,
is what we're concerned with right now.
And off to the side we have the ovary,
which has lots of different follicles in it,
and inside each follicle is an egg.
So really, just as 50,000 foot view of things,
the whole purpose of the menstrual cycle
is to select one of these follicles,
one of these follicles every menstrual cycle
for development.
So one of these follicles is selected to grow and develop.
And as it does that, as it grows and develops,
it secretes hormones, specifically estradiol,
so it specifically secretes estradiol,
which is a type of estrogen.
And that estradiol acts on the uterus
and it causes this inner lining of the uterus,
the endometrium to proliferate and to become thicker.
And then, in the middle of the menstrual cycle,
this one mature follicle ruptures
and it releases the egg that's inside it.
And that event, that event where the follicle ruptures
and releases the egg inside of it,
is referred to as ovulation.
After ovulation, the egg that's released travels down
the fallopian tube, hopefully to find
a sperm to fertilize it.
But meanwhile, this ruptured follicle that's
left behind over here, which is now referred to
as the corpus luteum,
so the corpus luteum takes this sort of waiting period
while it's sitting around waiting for the egg
to be fertilized to start producing lots of progesterone.
So progesterone is another hormone
that the corpus luteum produces.
And again, the progesterone acts on the endometrium
of the uterus to increase the growth of glands
and cause the storage of glycogen.
And all of this is done to prepare the endometrium,
to prepare it for the implantation of an embryo.
Alright, so what does any of this have to do with a period?
Well, if that egg that's hanging out over there
doesn't get fertilized, the corpus luteum recognizes that
and it says, "Well, I guess there's no reason
"to prepare this endometrium for implantation."
So it stops making progesterone.
And without the progesterone, the endometrium
starts to slough off.
And that sloughing off of endometrium
is what's referred to as a period.
But, if instead the egg does become fertilized,
it will implant into the uterus.
And when it implants into the uterus,
it makes this hormone called human,
called human, human
chorionic
chorionic gonado,
gonadotropin, human chorionic gonadotropin.
Usually it's just referred to as HCG.
And human chorionic gonadotropin tells the
corpus luteum to stay alive and to keep making
progesterone, and that progesterone in turn
keeps the endometrium alive and healthy
so that it doesn't slough off and you don't
end up with a period.
So that is why, when an egg becomes fertilized,
when you become pregnant, you miss a period.
So that's a lot of information.
Now, a lot of the hormones that I just talked about
account for the other presumptive signs of pregnancy.
So nausea and vomiting, for example.
Lots of people wonder why do you become
so nauseous during pregnancy and one of the reasons
for the nausea is progesterone.
So progesterone is really good at relaxing smooth muscle.
And that's smooth muscle throughout the entire body,
including the smooth muscle of the GI tract.
And if you can imagine, if the smooth muscle of the GI tract
is relaxed instead of contracting,
food isn't gonna make it's way down the GI tract
like it should.
It kinda just sits there and it's...
and that piling up of food, that stasis of food,
causes nausea.
And, in addition to all of the estrogen and progesterone,
the placenta makes a hormone called
melanocyte stimulating hormone.
It's not the most important hormone of pregnancy,
but it makes this hormone called melanocyte
stimulating hormone which does exactly
what the name implies, it stimulates the melanocytes,
which are the pigment cells in your skin.
So hyper pigmentation is not an uncommon
sign in pregnancy.
So darkening of the skin can also occur
as a sign in pregnancy.
And that could be hyper pigmentation of the face.
So the hyper pigmentation of the face is called melasma,
and a lot of people refer to it as the mask of pregnancy.
So you can see dark, blotchy spots on the face
which typically go away within a year
after the pregnancy is over, but still it can be
a sign early on in the pregnancy.
Linea nigra is another manifestation
of that hyper pigmentation.
So linea means line and nigra means black, right?
So it's a dark line that tends to appear
down the middle of the abdomen.
And also you can see darkening of the areola
of the breasts.
So that's another manifestation of the hyper pigmentation.
And speaking of the breast, many women early on
in the pregnancy experience breast tenderness.
And again, that's due to the effects of estrogen
and progesterone causing growth of the glands
inside the breast.
And then somewhere around 12 to 14 weeks
into the pregnancy, women can start to experience
fetal movements for the very first time
and they're commonly described as being
flutter-like, so it feels like a flutter.
And those movements are referring to as quickening.
Quickening.
Right, so quickening.
So those are the presumptive signs of pregnancy.
So what about the probable signs of pregnancy?
Well first there's uterine enlargement.
So if the examiner feels an enlarged uterus,
that's a pretty big clue that the woman might be pregnant.
And of course a positive pregnancy test
is another big sign.
So most pregnancy tests, whether they're
blood tests or whether they're urine tests,
detect beta HCG, they detect that
human chorionic gonadotropin.
And beta HCG is remember, made after
the implantation occurs and it can be
detected in the urine or in the blood
anywhere between 10 to 14 days after conception.
And I think there tends to be this thought
that blood pregnancy tests are way more accurtate
than urine tests that are done at home.
But that's not necessarily true.
So there have been a few studies that have shown
that a urine pregnancy test is pretty much
as accurate as a blood test,
but it's improper usage or not correctly
following instructions at home that tend to result
in an inaccurate home pregnancy test.
And you might be wondering why a positive
pregnancy test isn't a positive sign of pregnancy.
Why is it a probable sign of pregnancy?
And it's because you can actually have
a false positive pregnancy test.
And because there are certain types of cancer
that also produce HCG, so as you can imagine
that would also lead to a positive pregnancy test
in the absence of a pregnancy.
Alright, now as far as the remainder
of the probable signs of pregnancy,
keep in mind that during pregnancy the blood flow
to the entire reproductive tract, including
the uterus and the vagina drastically increases.
There are more blood vessels growing in these organs
and more of mom's blood is being directed this way.
And that makes these tissues really quite loose
and swollen and elastic.
So, for example, the tip of the cervix
becomes soft and swollen and that can be seen
or it can be felt by an examiner.
And that softening of the tip of the cervix
is referred to as Goodell's sign.
It's referred to as Goodell's sign,
so it's something an examiner can see that would
sort of indicate that the woman might be pregnant.
And all of those blood vessels give the cervix
and the vagina a violet, bluish color
which again can be seen during an exam.
And that's referred to as Chadwick's sign.
It refers to the bluish tinge
of the vagina and the cervix.
And eventually, actually, an examiner
can feel the presence of the fetus.
So, there is this maneuver where
the examiner can insert their finger
through the vagina and gently tap upwards,
which causes the fetus to rise.
And then the fetus sinks and then the examiner
feels a gentle tap back on their finger.
And that technique of gently, sort of bouncing
the floating fetus is referred to as ballottement.
It's referred to as ballott,
as ballottement.
So those are the probable signs of pregnancy,
leaving us with the positive signs of pregnancy,
which are signs that can only and only
be explained by pregnancy.
So they include visualizing the fetus,
so direct visualization of the fetus either
through ultrasound, x-ray.
Also hearing fetal heart tones.
Hearing fetal heart tones and feeling fetal movements.
Feeling fetal movements.
So visualizing the fetus, hearing
the fetal heart tones, and feeling fetal movements
are signs that are absolutely diagnostic of pregnancy.
They can't be explained by anything else.
Alright, so those are some of the different ways
we can tell if a woman is pregnant,
which just shows you that we've come a pretty far way
from the days of urinating on bags of barley and wheat.