The surprising effects of pregnancy
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0:08 - 0:11Muscles and joints shift and jostle.
-
0:11 - 0:17The heart’s pounding rhythm speeds up.
Blood roars through arteries and veins. -
0:17 - 0:21Over the course of a pregnancy,
every organ in the body changes. -
0:21 - 0:24Ignited by a range of hormones,
-
0:24 - 0:27these changes begin
as soon as pregnancy begins. -
0:30 - 0:36Just days after fertilization, the embryo
implants in the lining of the uterus. -
0:36 - 0:40Because its DNA doesn’t exactly match
the mother’s, -
0:40 - 0:44the immune system should theoretically
recognize it as an invader, -
0:44 - 0:48attack, and destroy it, like it would
bacteria or other harmful microbes. -
0:48 - 0:52That’s the challenge:
the mother’s immune system -
0:52 - 0:57needs to protect both her and the fetus,
but can’t act as it usually does. -
0:57 - 1:01What happens is not as simple
as decreasing the immune response. -
1:01 - 1:06Instead, it’s a complex interaction
we’re just beginning to understand, -
1:06 - 1:09involving many different types
of immune cells— -
1:09 - 1:14some of which seem to protect the fetus
from attack by other immune cells. -
1:16 - 1:21The body also creates an antibacterial
plug made of mucus on the cervix, -
1:21 - 1:25which keeps germs away
and stays sealed until labor. -
1:25 - 1:26As a pregnancy progresses,
-
1:26 - 1:30the uterus expands upward and outward
with the growing fetus. -
1:30 - 1:34To make room, hormones
called progesterone and relaxin -
1:34 - 1:36signal muscles to loosen.
-
1:36 - 1:41The muscles that propel food and waste
through the digestive tract also loosen, -
1:41 - 1:43which makes them sluggish,
-
1:43 - 1:47causing constipation as passage
through the tract slows down. -
1:47 - 1:49Loosened muscles
at the top of the stomach -
1:49 - 1:52might allow acid to escape
into the esophagus and throat, -
1:52 - 1:54causing heartburn and reflux.
-
1:54 - 1:57These changes can worsen morning sickness,
-
1:57 - 2:03which is caused in part by hormone HCG—
and can also happen at other times of day. -
2:03 - 2:06As the uterus grows,
it pushes on the diaphragm, -
2:06 - 2:10the muscle that expands and contracts
the chest with each breath. -
2:10 - 2:13This limits the diaphragm’s range.
-
2:13 - 2:18To compensate, the hormone progesterone
acts as a respiratory stimulant, -
2:18 - 2:21making the pregnant woman breathe
faster so both she and the baby -
2:21 - 2:25can both get enough oxygen
with less lung capacity. -
2:25 - 2:29This all may leave the pregnant woman
feeling short of breath. -
2:29 - 2:33Meanwhile, the kidneys
make more erythropoietin, -
2:33 - 2:36a hormone that increases
red blood cell production. -
2:39 - 2:44The kidneys also keep extra water and salt
rather than filtering it out into urine -
2:44 - 2:46to build up the volume of the blood.
-
2:46 - 2:51A pregnant woman’s blood volume
increases by 50% or more. -
2:51 - 2:52But it’s also a bit diluted,
-
2:52 - 2:56because it only has 25%
more red blood cells. -
2:56 - 3:00Usually, the body makes blood cells
using iron from our food. -
3:00 - 3:04But during pregnancy, the fetus
is also building its own blood supply -
3:04 - 3:06from nutrients in the mother’s food—
-
3:06 - 3:09leaving less iron and other nutrients
for the mother. -
3:09 - 3:12The heart has to work extra hard
to pump all this blood -
3:12 - 3:14through the body and placenta.
-
3:14 - 3:17A pregnant woman’s heart rate increases,
-
3:17 - 3:21but we don’t fully understand how blood
pressure changes in a healthy pregnancy— -
3:21 - 3:23an important area of research,
-
3:23 - 3:26because some of the most serious
complications -
3:26 - 3:29are related to the heart
and blood pressure. -
3:29 - 3:32The expanding uterus may press on veins—
-
3:32 - 3:35causing fluid buildup
in the legs and feet. -
3:35 - 3:39If it presses on a large vein
called the inferior vena cava, -
3:39 - 3:42it might interfere with blood
returning to the heart, -
3:42 - 3:47causing a dizzying drop in blood pressure
after standing for too long. -
3:47 - 3:51Some of these changes start
to reverse even before birth. -
3:51 - 3:55Shortly before delivery,
the fetus drops down, -
3:55 - 3:57decreasing the pressure on the diaphragm
-
3:57 - 4:01and allowing the pregnant woman
to take deeper breaths. -
4:01 - 4:02During labor and birth,
-
4:02 - 4:06much of the extra fluid in the body
is lost when the water breaks. -
4:09 - 4:13The uterus shrinks back down
in the weeks after birth. -
4:13 - 4:17Like the rest of the body,
pregnancy affects the brain— -
4:17 - 4:20but its effects here are some
of the least understood. -
4:20 - 4:23Recent studies show differences
in brain scans -
4:23 - 4:26after pregnancy and early parenting,
-
4:26 - 4:29and suggest that these changes
are adaptive. -
4:29 - 4:32That means they could help
with parenting skills, -
4:32 - 4:38such as an increased ability to read
facial cues since babies can’t talk. -
4:38 - 4:41The lack of information about pregnancy’s
effects on the brain -
4:41 - 4:47highlights a general truth: historically,
almost all the research around pregnancy -
4:47 - 4:51has focused on the fetus,
rather than pregnant women. -
4:51 - 4:54Experiences of pregnancy vary widely,
-
4:54 - 4:56both within the range
of healthy pregnancies -
4:56 - 5:02and due to complicating health conditions—
new research will help us understand why, -
5:02 - 5:05and develop effective treatments
where necessary. -
5:05 - 5:09In the meantime,
every pregnancy is different, -
5:09 - 5:12and it’s important to consult a doctor
with any specific questions. -
5:13 - 5:17Today, we’re turning an exciting corner,
-
5:17 - 5:22as more research is devoted
to the astounding biology of pregnancy.
- Title:
- The surprising effects of pregnancy
- Speaker:
- TED-Ed
- Description:
-
View full lesson: https://ed.ted.com/lessons/the-surprising-effects-of-pregnancy
Muscles and joints shift and jostle. The heart’s pounding rhythm speeds up. Blood roars through arteries and veins. Over the course of a pregnancy, every organ in the body changes. Initiated by a range of hormones, these changes begin as soon as a pregnancy begins. Explore what we know— and don’t know— about pregnancy's effects on the body and brain.
Lesson by TED-Ed, directed by Roxane Campoy and Charlotte Cambon.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TED-Ed
- Duration:
- 05:25
Elise Haadsma approved English subtitles for The surprising effects of pregnancy | ||
Elise Haadsma accepted English subtitles for The surprising effects of pregnancy | ||
lauren mcalpine edited English subtitles for The surprising effects of pregnancy |