The surprising effects of pregnancy

翻译人员: Lengying Khoo

Muscles and joints shift and jostle.

肌肉与关节发生移位和挤压。

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

心跳节奏加快， 血液在动脉和静脉中轰鸣。

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

在怀孕过程中， 体内的每个器官都在发生变化。

Ignited by a range of hormones,

由一系列激素引发的

these changes begin as soon as pregnancy begins.

这些变化在怀孕初期便会出现。

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

在受精后的几天内， 胚胎就会被植入子宫内膜。

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

因为它的 DNA 与母亲的 DNA 不完全匹配，

the immune system should theoretically recognize it as an invader,

理论上来说，免疫系统 会将它视为一个入侵者，

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

并对其实施攻击和摧毁，就如同 对待细菌和其他的有害微生物一样。

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

于是挑战出现了：母亲的免疫系统 需要同时保护自身和胎儿，

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

但又不能像往常那样运作。

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

事情并不像降低免疫反应那么简单。

相反的，这是一个复杂的相互作用， 对此我们也才刚刚有所了解。

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

involving many different types of immune cells—

它涉及许多不同类型的免疫细胞——

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

其中一些细胞似乎在保护胎儿 免受其他免疫细胞的攻击。

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

人体还在子宫颈上制造了 一个由粘液构成的抗菌栓，

which keeps germs away and stays sealed until labor.

以防止细菌入侵 并保持密封直至分娩。

As a pregnancy progresses,

随着妊娠的推进，

the uterus expands upward and outward with the growing fetus.

子宫会随着胎儿的生长 而向上和向外伸展。

To make room, hormones called progesterone and relaxin

为了腾出空间， 被称为孕酮和松弛素的激素

signal muscles to loosen.

会对肌肉发出放松的信号。

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

那些在消化道内推动食物 和排泄物的肌肉也会变得松弛。

which makes them sluggish,

这使肌肉运动变得迟缓，

causing constipation as passage through the tract slows down.

使其通过消化道的速度放慢， 因而造成便秘。

Loosened muscles at the top of the stomach

胃部上方松弛的肌肉

might allow acid to escape into the esophagus and throat,

可能使胃酸逃入食道和咽喉，

causing heartburn and reflux.

引起胃灼热和逆流。

These changes can worsen morning sickness,

这些变化会加剧晨间孕吐。

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

这一部分是由 HCG 激素引起—— 也可能发生在一天中的其他时间。

As the uterus grows, it pushes on the diaphragm,

不断胀大的子宫会挤压横膈膜，

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

一种每次呼吸都会 扩张和收缩胸部的肌肉，

This limits the diaphragm’s range.

这也限制了横膈膜的运动范围。

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

作为弥补，黄体酮激素发挥了 呼吸兴奋剂的作用。

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

它使孕妇呼吸加快，

让她和胎儿在肺活量减小的情况下， 也可以得到足够的氧气。

can both get enough oxygen with less lung capacity.

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

这也可能使孕妇感到喘不过气。

Meanwhile, the kidneys make more erythropoietin,

同时，肾脏制造出 更多的红血球生成素，

a hormone that increases red blood cell production.

一种提高红细胞生成的激素。

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

肾脏还会把额外的水和盐分储存起来， 而不是将其过滤到尿液中，

to build up the volume of the blood.

以增加血液容量。

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

孕妇的血液容量 会增加 50% 以上。

But it’s also a bit diluted,

但血液也被稍微稀释了，

because it only has 25% more red blood cells.

因为其中的红细胞含量 只增加了 25%。

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

通常，人体利用食物中的 铁元素制造血细胞。

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

但在怀孕期间，胎儿也从 母亲的食物中吸收营养

以建立自己的血液供应，

from nutrients in the mother’s food—

leaving less iron and other nutrients for the mother.

从而减少了母亲体内的 铁和其他营养成分。

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

心脏必须格外用力

through the body and placenta.

才能把血液泵送到全身和胎盘。

A pregnant woman’s heart rate increases,

孕妇的心率会增加，

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

但我们还不完全了解 血压在健康妊娠内如何变化——

an important area of research,

这是一个重要的研究领域，

because some of the most serious complications

因为一些严重的并发症

are related to the heart and blood pressure.

与心脏和血压有关。

The expanding uterus may press on veins—

扩展中的子宫会压迫静脉

causing fluid buildup in the legs and feet.

造成下肢水肿。

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

如果压迫到被称为 下腔静脉的大静脉上，

it might interfere with blood returning to the heart,

就可能干扰到血液流回到心脏，

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

导致孕妇在站立过久后 血压下降，感到眩晕。

Some of these changes start to reverse even before birth.

其中有些变化甚至 在婴儿出生前就会开始发生逆转。

Shortly before delivery, the fetus drops down,

在分娩前夕，胎儿的位置下移，

decreasing the pressure on the diaphragm

从而减轻了对横膈膜的压力，

and allowing the pregnant woman to take deeper breaths.

使孕妇能够进行深呼吸。

During labor and birth,

在分娩期间，

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

体内多余的积水 会因羊水破裂而流失。

The uterus shrinks back down in the weeks after birth.

子宫会在分娩后的几周内收缩。

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

就像身体的其他部分一样， 妊娠会影响大脑——

but its effects here are some of the least understood.

但我们对其影响却知之甚少。

Recent studies show differences in brain scans

最新的研究显示， 妊娠后和早期育儿阶段的

after pregnancy and early parenting,

大脑成像上存在差异，

and suggest that these changes are adaptive.

表明这些变化是适应性的。

That means they could help with parenting skills,

这也说明它们可能有助于 提高育儿技巧。

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

比如，由于婴儿不会说话， 母亲对面部表情的读解能力会有所提升。

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

缺乏有关妊娠 对大脑影响的信息

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

也突出了一个普遍的事实： 几乎所有历来有关妊娠的研究

has focused on the fetus, rather than pregnant women.

针对的都是胎儿，而非孕妇。

Experiences of pregnancy vary widely,

对妊娠的体验存在着很大的差异，

both within the range of healthy pregnancies

这既出现在健康妊娠范畴中，

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

也由复杂的健康状况引起—— 新的研究将帮助我们了解其原因，

and develop effective treatments where necessary.

并开发出必要和有效的治疗方法。

In the meantime, every pregnancy is different,

同时，每次妊娠的情况都不同，

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

因而向医生咨询任何具体问题 是非常重要的。

Today, we’re turning an exciting corner,

今天，我们迎来了 一个激动人心的转折点，

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

致力于令人震惊的 怀孕生物学的研究正在蓬勃发展。