Her birth revolutionized the field of reproductive medicine.

她的誕生徹底改變了生殖醫學領域。

Given that approximately 1 in 8 heterosexual couples has difficulty conceiving,

由於約每 8 對異性戀夫婦中就有 1 對面臨受孕困難，

and that homosexual couples and single parents often need clinical help to make a baby,

還有同性伴侶和單親父母通常需要臨床協助才能生下孩子，

the demand for IVF has been growing.

試管內受精的需求不斷增長。

IVF is so common that more than 5 million babies have been born through this technology.

IVF 極為普遍，迄今約有逾 5 百萬名嬰兒透過這項技術誕生。

IVF works by mimicking the brilliant design of sexual reproduction.

IVF 技術模擬了偉大的有性生殖原理。

In order to understand IVF, we first need to take a look at the natural process of baby-making.

為了理解 IVF 技術，我們首先需要了解自然受孕的過程。

Believe it or not, it all starts in the brain.

無論你相不相信，一切都從大腦開始。

Roughly 15 days before fertilization can happen,

受孕期前約 15 天，

the anterior pituitary gland secretes follicle-stimulating hormone, FSH,

腦下垂體前葉會分泌促卵泡激素（FSH），

which ripens a handful of follicles of the ovary that then release estrogen.

使卵巢內的卵泡成熟並分泌雌激素。

Each follicle contains one egg, and on average, only one follicle becomes fully mature.

每個卵泡內都有一顆卵子，而平均只有一顆卵泡會發育成熟。

As it grows and continues to release estrogen,

隨著卵泡的成長，

this hormone not only helps coordinate growth and preparation of the uterus,

腦下垂體前葉持續分泌幫助子宮成長和預備的雌激素，

it also communicates to the brain how well the follicle is developing.

同時知會大腦卵泡的發育狀況。

When the estrogen level is high enough,

當雌激素分泌到達高峰時，

the anterior pituitary releases a surge of luteinizing hormone, LH,

腦下垂體前葉會分泌促黃體生成激素（LH），

which triggers ovulation and causes the follicle to rupture and release the egg.

促使排卵並使卵泡破裂以釋放卵子。

Once the egg leaves the ovary, it is directed into the fallopian tube by the finger-like fimbriae.

卵子一旦離開卵巢，就會被手指狀的纖毛導入輸卵管。

If the egg is not fertilized by sperm within 24 hours,

如果卵子沒有在 24 小時內受精，

the unfertilized egg will die, and the entire system will reset itself,

未受精的卵子會自然死亡，整個系統會重置，

preparing to create a new egg and uterine lining the following month.

為下個月製造新卵子和子宮內膜準備。

The egg is the largest cell in the body

卵子是體內最大的細胞，

and is protected by a thick, extracellular shell of sugar and protein called the zona pellucida.

由糖和蛋白質所構成的厚厚一層細胞外膜保護著，稱為透明帶。

The zona thwarts the entry and fusion of more than one sperm, the smallest cell in the body.

透明帶阻撓超過一個精子（人體內最小細胞）的進入和融合。

It takes a man two to three months to make sperm, and the process constantly renews.

男性需要花二到三個月的時間製造精子，這個過程會持續地進行。

Each ejaculation during sexual intercourse releases more than 100 million sperm.

性交時每次射精都會釋出超過 1 億個精子。

But only 100 or so will ultimately make it to the proximity of the egg,

但只有 100 個左右最終會抵達卵子附近，

and only one will successfully penetrate through the armor of the zona pellucida.

而只有一個能夠成功穿越如鎧甲般的透明帶。

Upon successful fertilization,

受精成功後，

the zygote immediately begins developing into an embryo and takes about three days to reach the uterus.

受精卵就立即發育成胚胎，並在三天左右抵達子宮。

There, it requires another three or so days to implant firmly into the endometrium, the inner lining of the uterus.

在子宮內，受精卵還需要三天左右的時間，才能牢固地附著在子宮內膜上。

Once implanted,

一旦著床，

the cells that are to become the placenta secrete a hormone that signals to the ovulated follicle that there is a pregnancy in the uterus.

即將發育為胎盤的細胞會分泌一種激素，以通知卵泡子宮成功受孕。

This helps rescue that follicle, now called the corpus luteum, from degenerating as it normally would do in that stage of the menstrual cycle.

這可以讓卵泡（現稱黃體）免於月經的週期性剝落。

The corpus luteum is responsible for producing the progesterone required to maintain the pregnancy until six to seven weeks of gestation,

黃體負責製造維持妊娠所需的黃體素，接著大約在六至七週時，

when the placenta develops and takes over, until the baby is born approximately 40 weeks later.

由完成發育的胎盤接管，直到約 40 週後嬰兒出生為止。

Now, how do you make a baby in a lab?

那麼，在實驗室裡如何製造寶寶呢？

In patients undergoing IVF,

接受 IVF 的患者，

FSH is administered at levels that are higher than naturally occurring

其 FSH 指數會被注射至高於自然分泌量，

to cause a controlled overstimulation of the ovaries

以進行控制性卵巢刺激，

so that they ultimately produce multiple eggs.

好製造更多卵子。

The eggs are then retrieved just before ovulation would occur,

然後會於排卵前，

while the woman is under anesthesia, through an aspirating needle that is guided by ultrasound.

女性處於麻醉狀態下，用超音波導引的吸引針將卵子取出。

Most sperm samples are produced by masturbation.

多數的精液樣本是由自慰方式採集。

In the laboratory, the identified eggs are stripped of surrounding cells and prepared for fertilization in a petri dish.

在實驗室裡，篩選出來的卵子會被剝去細胞外壁，在培養皿內等待受孕。

Fertilization can occur by one of two techniques.

受精的方法有兩種，可擇一進行。

In the first, the eggs are incubated with thousands of sperm and fertilization occurs naturally over a few hours.

第一種的狀況下，卵子與成千上萬個精子一起孵育，並在幾個小時內自然受孕。

The second technique maximizes certainty of fertilization by using a needle to place a single sperm inside the egg.

第二種技術是用一根針，將單個精子置入卵子中，將受孕成功機率最大化。

This is particularly useful when there is a problem with the quality of the sperm.

當精子品質有問題時，這種方法尤其有用。

After fertilization, embryos can be further screened for genetic suitability,

受孕後，可繼續篩查胚胎的基因適應性，

frozen for later attempted pregnancies, or delivered into the woman's uterus via catheter.

將其冷凍以備日後受孕，或透過導管置入子宮。

Common convention is to transfer the embryo three days after fertilization when the embryo has eight cells,

一般慣例是在受精後三天移植胚胎，此時胚胎有八個細胞，

or on day five when the embryo is called a blastocyst and has hundreds of cells.

或在第五天，此時胚胎被稱為囊胚，擁有數百個細胞。

If the woman's eggs are of poor quality due to age or toxic exposures, or have been removed due to cancer,

如果女性的卵子因為年齡或暴露於不良狀態而品質低劣或是因為癌症而被移除，

donor eggs may be used.

可以使用供體卵（或稱捐獻卵）。

In the case that the intended mother has a problematic uterus, or lacks one,

在目標母體子宮有問題或沒子宮的情況下，

another woman, called the gestational carrier or surrogate, can use her uterus to carry the pregnancy.

另一位稱為「代理孕母」的女性可提供子宮進行受孕、分娩。

To increase the odds of success,

為了提升成功機率，

which are as high as 40% for a woman younger than 35,

（35 歲以下女性成功機率可高達 40%）

doctors sometimes transfer multiple embryos at once,

醫生有時會一次移植多顆卵子，

which is why IVF results in twins and triplets more often than natural pregnancies.

這也就是 IVF 比自然受孕更常出現多胞胎的原因。

However, most clinics seek to minimize the chances of multiple pregnancies,

然而，多數診所都希望最小化多胞胎的機率，

as they are riskier for mothers and babies.

因為這對媽媽和嬰兒的風險都更大。

Millions of babies, like Louise Brown, have been born from IVF and have had normal, healthy lives.

數百萬個嬰兒都跟 Louis Brown 一樣透過 IVF 誕生，並過著正常、健康的生活。

The long-term health consequences of ovarian stimulation with IVF medicines are less clear,

IVF 藥物刺激卵子在健康上的後遺症較不清楚，

though so far, IVF seems safe for women.

不過到目前為止，IVF 對女性而言似乎安全。

Because of better genetic testing, delayed childbearing, increased accessibility, and diminishing cost,

有鑑於基因檢測、延遲受孕技術進步、易取得性提升以及費用降低，

it's not inconceivable that artificial baby-making via IVF and related techniques could outpace natural reproduction in years to come.

未來用 IVF 及相關技術進行人工受孕多過自然繁衍的情況也不是沒可能的。