The heart's pounding rhythm speeds up. Blood roars through arteries and veins.

肌肉與關節發生移位和擠壓。

Over the course of a pregnancy, every organ in the body changes.

心跳節奏加快。

Ignited by a range of hormones,

血液在動脈和靜脈中轟鳴。

these changes begin as soon as pregnancy begins.

在妊娠過程中， 體內的每個器官都發生變化。

Just days after fertilization, the embryo implants in the lining of the uterus.

這些變化由一系列激素引發，

Because its DNA doesn't exactly match the mother's,

在妊娠一開始時便出現了。

the immune system should theoretically recognize it as an invader,

在受精後的幾天內， 胚胎就會被植入子宮內膜。

attack, and destroy it, like it would bacteria or other harmful microbes.

因為它的 DNA 與 母親的 DNA 不完全匹配，

That's the challenge: the mother's immune system

所以，理論上講，免疫系統 會將它視為一個入侵者，

needs to protect both her and the fetus, but can't act as it usually does.

從而對其實施攻擊和摧毀，就如同 對待細菌和其他的有害微生物一樣。

What happens is not as simple as decreasing the immune response.

這是一個挑戰：母親的免疫系統

Instead, it's a complex interaction we're just beginning to understand,

需要同時保護自身和胎兒， 但又不能像通常那樣運作。

involving many different types of immune cells—

事情並不像降低 免疫反應那麼簡單。

some of which seem to protect the fetus from attack by other immune cells.

相反，這是一個複雜的相互作用， 我們對此也才剛剛有所了解。

The body also creates an antibacterial plug made of mucus on the cervix,

它涉及許多不同類型的免疫細胞——

which keeps germs away and stays sealed until labor.

其中一些細胞似乎在保護胎兒 免受其他免疫細胞的攻擊。

As a pregnancy progresses,

人體還在子宮頸上製造了 一個由粘液構成的抗菌栓，

the uterus expands upward and outward with the growing fetus.

它可以防止細菌入侵 並保持密封直至分娩。

To make room, hormones called progesterone and relaxin

隨著妊娠的推進，

signal muscles to loosen.

子宮會隨著胎兒的生長 而向上和向外膨脹。

The muscles that propel food and waste through the digestive tract also loosen,

為了騰出空間，兩種被稱為 孕酮和鬆弛素的激素

which makes them sluggish,

會向肌肉發出放鬆的信號。

causing constipation as passage through the tract slows down.

那些在消化道內推動食物 和排泄物的肌肉也會變得鬆弛。

Loosened muscles at the top of the stomach

這就使肌肉運動變得遲緩，

might allow acid to escape into the esophagus and throat,

從而造成便秘，因為其通過 消化道的速度放慢了。

causing heartburn and reflux.

胃部上方鬆弛的肌肉

These changes can worsen morning sickness,

可能會使胃酸逸入食道和咽喉，

which is caused in part by hormone HCG— and can also happen at other times of day.

引起胃灼熱和逆流。

As the uterus grows, it pushes on the diaphragm,

這些變化會加劇晨間孕吐。

the muscle that expands and contracts the chest with each breath.

它部分是由 HCG 激素引起的—— 也可能發生在一天中的其他時間。

This limits the diaphragm's range.

隨著生長，子宮會擠壓橫膈膜；

To compensate, the hormone progesterone acts as a respiratory stimulant,

橫膈膜是每次呼吸時 控制胸腔擴張和收縮的肌肉。

making the pregnant woman breathe faster so both she and the baby

這就限制了橫隔膜的運動範圍。

can both get enough oxygen with less lung capacity.

作為彌補，黃體酮激素發揮了 呼吸興奮劑的作用，

This all may leave the pregnant woman feeling short of breath.

它使孕婦呼吸加快，以便讓她和胎兒

Meanwhile, the kidneys make more erythropoietin,

在肺活量減小的情況下 都可以得到足夠的氧氣。

a hormone that increases red blood cell production.

這都可能使孕婦感到喘不過氣。

The kidneys also keep extra water and salt rather than filtering it out into urine

同時，腎臟製造出 更多的紅血球生成素，

to build up the volume of the blood.

一種提高紅細胞生成的激素。

A pregnant woman's blood volume increases by 50% or more.

腎臟還把額外的水和鹽分儲存了 起來，而不是將其過濾到尿液中

But it's also a bit diluted,

以此來增加血液容量。

because it only has 25% more red blood cells.

孕婦的血液容量會增加 50％ 以上。

Usually, the body makes blood cells using iron from our food.

但血液也被稍微稀釋了，

But during pregnancy, the fetus is also building its own blood supply

因為它的紅細胞只增多了 25％。

from nutrients in the mother's food—

通常，人體利用食物中的 鐵元素製造血細胞。

leaving less iron and other nutrients for the mother.

但是在懷孕期間，胎兒也在 建立自己的血液供應，

The heart has to work extra hard to pump all this blood

從母親的食物中吸收營養成分——

through the body and placenta.

從而減少了母親體內的 鐵和其他營養成分。

A pregnant woman's heart rate increases,

心臟必須格外用力

but we don't fully understand how blood pressure changes in a healthy pregnancy—

才能把血液泵送到全身和胎盤。

an important area of research,

孕婦的心率會增加，

because some of the most serious complications

但我們還不完全了解 血壓在健康妊娠內如何變化——

are related to the heart and blood pressure.

這是一個重要的研究領域，

The expanding uterus may press on veins—

因為一些最為嚴重的併發症

causing fluid buildup in the legs and feet.

與心臟和血壓有關。

If it presses on a large vein called the inferior vena cava,

擴張中的子宮會壓迫靜脈——

it might interfere with blood returning to the heart,

造成下肢水腫。

causing a dizzying drop in blood pressure after standing for too long.

如果壓迫在被稱為 下腔靜脈的大靜脈上，

Some of these changes start to reverse even before birth.

它可能會干擾到血液回流到心臟，

Shortly before delivery, the fetus drops down,

站立過久後，會造成血壓下降， 令人感到眩暈。

decreasing the pressure on the diaphragm

其中一些變化甚至 在嬰兒出生前就開始發生逆轉。

and allowing the pregnant woman to take deeper breaths.

分娩前夕，胎兒下落，

During labor and birth,

從而減輕了對橫膈膜的壓力，

much of the extra fluid in the body is lost when the water breaks.

使孕婦能夠進行深呼吸。

The uterus shrinks back down in the weeks after birth.

在分娩期間，

Like the rest of the body, pregnancy affects the brain—

體內的大量積水 會因羊水破裂而流失。

but its effects here are some of the least understood.

子宮會在分娩後的幾週內收縮。

Recent studies show differences in brain scans

像身體的其他部分一樣， 妊娠會影響到大腦——

after pregnancy and early parenting,

但是我們對此處的影響卻知之甚少。

and suggest that these changes are adaptive.

最新研究顯示，

That means they could help with parenting skills,

在妊娠後及早期育兒階段 存在著大腦掃描上的差異，

such as an increased ability to read facial cues since babies can't talk.

表明這些變化是適應性的，

The lack of information about pregnancy's effects on the brain

可能有助於提升育兒技巧，

highlights a general truth: historically, almost all the research around pregnancy

比如，由於嬰兒不會說話，對面部 表情的解讀能力因此而得到提高。

has focused on the fetus, rather than pregnant women.

缺乏有關妊娠對大腦影響的信息

Experiences of pregnancy vary widely,

突顯出一個普遍的事實： 幾乎所有歷來關於妊娠的研究

both within the range of healthy pregnancies

針對的都是胎兒而非孕婦。

and due to complicating health conditions— new research will help us understand why,

對妊娠的體驗存在著很大差異。

and develop effective treatments where necessary.

這既出現在健康妊娠範疇中，

In the meantime, every pregnancy is different,

也由複雜的健康狀況引起。

and it's important to consult a doctor with any specific questions.

新的研究將幫助我們了解其原因

Today, we're turning an exciting corner,

並開發出必要和有效的治療方法。

as more research is devoted to the astounding biology of pregnancy.

同時，每次妊娠都不一樣，