According to the Egyptians,

古代エジプト人によれば

all you have to do is urinate on wheat and barley seeds, and wait.

小麦と大麦の粒に尿をかけて待ち

If either sprouts, congratulations, you're pregnant!

どちらかに芽が出れば おめでとうございます！ 御懐妊です！

And if wheat sprouts faster, it's a girl, but if barley, it's a boy.

そして小麦が先に芽が出れば女の子 大麦であれば男の子です

In 1963, a small study reproduced this test

1963年に このテストの 再現実験が行われ

and found that it predicted pregnancy with a respectable 70% accuracy,

ほぼ70％の確率で 妊娠を判別できることが分かりました

though it couldn't reliably tell the sex of the baby.

ただし 子供の性別までは 正しく判別できませんでした

Scientists hypothesized that the test worked

科学者はこのテストが 有効であると考えました

because pregnant women's urine contains more estrogen, which can promote seed growth.

なぜなら妊娠した女性の尿は 多くの女性ホルモンを含み

Now it's easy to take this ancient method for granted

苗の成長を促進するからです

because modern pregnancy tests give highly accurate results within minutes.

現代は当たり前のように この古代の方法を行うことができます

So how do they work?

なぜなら現代の妊娠検査は 数分間でとても正確な結果を出すからです

Over-the-counter pregnancy tests are all designed to detect one thing: a hormone called HCG.

ではこの仕組みはどのようなものでしょう？

HCG is produced in the earliest stages of pregnancy

市販の全ての妊娠検査は ある物質を検知するように設計されています

and starts a game of telephone that tells the body not to shed the inner lining of the uterus that month.

hCGと呼ばれるホルモンです

As the pregnancy progresses, HCG supports the formation of the placenta,

hCGは妊娠の初期に作られ

which transfers nutrients from mother to fetus.

伝言ゲームを始めます

The test starts when urine is applied to the exposed end of the strip.

その月に子宮の内壁が脱落しないよう 母体に伝えるのです

As the fluid travels up the absorbent fibers,

妊娠が進むと

it will cross three separate zones, each with an important task.

hCGは栄養を母親から胎児に送る

When the wave hits the first zone, the reaction zone,

胎盤の形成を助けます

Y-shaped proteins called antibodies will grab onto any HCG.

このテストは紙切れの端に 尿をつけると始まります

Attached to these antibodies is a handy enzyme with the ability to turn on dye molecules,

液体は吸水性繊維を通じ

which will be crucial later down the road.

それぞれ重要な役目をもつ 3つの区間を通ります

Then the urine picks up all the AB1 enzymes and carries them to the test zone, which is where the results show up.

１つ目は反応区間です

Secured to this zone are more Y-shaped antibodies that will also stick to HCG on one of its five binding sites.

抗体と呼ばれるY型のタンパク質が hCGを捕まえます

Scientists call this type of test a sandwich assay.

これらの抗体には それ以降の過程で重要となる

If HCG is present, it gets sandwiched between the AB1 enzyme and AB2,

色素分子を発色させる能力を持った 便利な酵素が結合しています

and sticks to the test zone, allowing the attached dye-activating enzyme to do its job and create a visible pattern.

そして尿が全てのAB1酵素に結合し

If there's no HCG, the wave of urine and enzymes just passes on by.

テスト区域に移動させると 結果が現れます

Finally, there's one last stop to make, the control zone.

この区域には さらにY型の抗体があり

As in any good experiment, this step confirms that the test is working properly.

hCGの５つの結合部位の１つに 結合します

Whether the AB1 enzymes never saw HCG,

科学者はこのタイプのテストを サンドイッチアッセイと呼びます

or they're extras because Zone 1 is overstocked with them,

hCGが存在すると AB1とAB2酵素の間に挟まれ

all the unbound AB1 enzymes picked up in Zone 1 should end up here and activate more dye.

テスト区間に結合します

So if no pattern appears, that indicates that the test was faulty.

色素活性化酵素が活動を始め

These tests are pretty reliable, but they're not failproof.

模様を生み出します

For instance, false negatives can occur if concentrations of HCG aren't high enough for detection.

もしhCGがなければ 尿と酵素は単に区間を通り抜けてしまいます

After implantation, HCG levels double every two to three days, so it may just be too early to tell.

最後は対照区間です

And beverages can dilute the urine sample,

実験が有効であれば

which is why doctors recommend taking the test first thing in the morning.

この段階で実験が正しく 機能していることを証明します

On the other hand, false positives can come from other sources of HCG,

AB1酵素がhCGを見つけなかったか

like IVF injections, ectopic pregnancies,

最初の区間で酵素が過剰であった場合には

or certain cancers such as uterine cancer or testicular cancer,

最初の区間にあった 全ての未結合AB1酵素がここまで運ばれ

making it possible for one of these tests to tell a man he's pregnant.

ここでも発色を行うのです

The best way for a woman to find out for sure is at the doctor's office.

もし何の模様も現れなければ 検査は失敗であることを示します

The doctors are also looking for HCG,

これらの検査はかなり信頼性が高いものの 完全なものではありません

but with tests that are more sensitive and quantitative,

例えば見逃しが起こりえます

which means they can determine the exact level of HCG in your blood.

例えばhCGの濃度が 検知されるほど十分でない場合です

A few minutes can feel like forever when you're waiting on the results of a pregnancy test.

受精卵の着床後に hCGの濃度は２、３日毎に倍増します

But in that brief time, you're witnessing the power of the scientific method.

そのため単に早すぎただけかもしれません

That one little stick lets you ask a question,

また飲み物は尿のサンプルを薄めます

perform a controlled experiment,

それが医師が朝一番に 検査することを勧める理由です

and then analyze the results to check your original hypothesis.

その一方で 誤った陽性反応も hCGの他の発生源―

And the best part is you won't even have to wait until the next harvest.

たとえば体外受精の注射や子宮外妊娠