[narrator] This is a 17th-century Dutch scientist's sketch of a "homunculus,"
a tiny, fully-formed human being
that according to one popular theory of the day
was curled up inside the head of each sperm.
Once the miniature person entered the woman's body,
it grew into a full-size human.
A competing theory at the time claimed
that the miniature human actually lived in the egg, not the sperm.
For 100 years, so-called "spermists" and "ovists"
duked it out over who held the key to creating new life,
until both theories died with more powerful microscopes.
Then in the 19th century,
a German zoologist discovered how babies are really made:
a sperm and an egg fusing together, each playing an equal role.
We'd solved the mystery of life.
Well, at least one part.
I will never forget the phone call I received
that kind of started this whole process.
Immediately, I heard her crying, and she said they didn't find sperm.
She said they-- they found zero.
And...
that's when my heart dropped.
I remember falling to the ground in the lobby on my knees and just...
You just don't want to believe that it could happen to you.
Male infertility around the globe,
even though it's so important in terms of infertility,
is a hidden reproductive health problem.
It was really hard.
You go through really dark times
when you see, you know, your friends having kids,
and here you are almost six years down the road
and... still trying to figure it out. [chuckles]
[narrator] Our species only exists because we reproduce.
So, why can't so many of us do it?
What part of the mystery of life is still unsolved?
-Dad. -Yes?
Where do babies come from?
[theme music playing]
[man] The whole field of fertilization has expanded and advanced.
We help couples have babies in ways
that we wouldn't have thought possible years ago.
[woman] I can't believe that she's ours and that she's in our lives.
The patients here, they say, "Doctor, it's-- it's a crucial thing.
I want to keep my fertility."
[narrator] For most people, if you have sex at the right time,
there's a decent chance this will happen...
a sperm meeting an egg.
But we're pretty bad at having sex at the right time.
The truth is that your egg is only good for about eight hours after you ovulate.
That's it.
And you'll never get that timing right.
It's impossible to get that right.
You're better off just having intercourse regularly,
three times a week at least.
After intercourse, the sperm are good
for about three days in the female's tract.
So, you always want to have sperm there when you ovulate.
And that's because fertilization isn't a sperm battle royal,
a frantic sprint between millions of aggressive sperm to penetrate the egg.
It's more like the labyrinth in the 1986 classic Labyrinth:
full of obstacles that sometimes hurt and sometimes help.
I think I'm getting smarter!
This is a piece of cake. [screams]
Stop it! Help!
What do you mean, "help"?
-We are helping. -[Sarah gasps]
We're helping hands.
[narrator] And the labyrinth is unsolvable,
except in that brief golden window or terrifying window.
Depending on whether or not you want to get pregnant,
a delicate hormonal cocktail has put everything in place.
First, the cervix, the gatekeeper to the uterus,
is slightly open.
It denies entry to 99.9% of the sperm, who die in the vagina.
It's not necessarily the fastest sperm who get in or the strongest.
But you'll probably get kicked out if you're a real freak.
-[buzzer sounds] -[sperm screams]
[narrator] And it's not always a mad dash.
Some sperm laze around for days in a canal in the cervix
in little inlets called crypts.
It's a brief cervical Riviera vacation.
And then the sperm begin their quest into the uterus.
But first, the cervix outfits them with armor, a nutrient rich fluid.
Without it, they'd all die.
Once the sperm are in,
they're not so much swimming frantically as they are pushed.
Sperm do crawl up the uterine wall,
but they're propelled forward by uterine contractions.
So the ones that make it to the Fallopian tubes
may not be the fastest swimmers.
They may have just gotten a good nudge.
The tubes keep the sperm nice and safe in their walls
until the egg enters,
-making the sperm hyperactive. -[sperm exclaim]
[narrator] And they get one last assist from the labyrinth.
Little hairs in the tube point them the right way,
and then they swim like hell.
The ones that make it to the egg latch on,
-and maybe one gets through. -[sperm] Whoo-hoo!
[narrator] The lucky sperm is just that: lucky.
"Powerball lottery winner" lucky.
Literally, their chances were one in 250 million.
And it's tough for a reason.
If more than one sperm manages to fertilize an egg,
the resulting embryo can't survive.
That's why scientists think all these obstacles evolved in the first place.
And it's why it can take a little while to get pregnant.
There was no reason to believe that we were gonna have any issues.
[narrator] For an average couple having unprotected sex,
it happens within six months.
Even after trying for a few months, we just kept thinking
that next month will be the month.
Then next month turned into six months later, turned into a year.
[narrator] After 12 months, around 15% of couples still aren't pregnant.
I'd say around a year,
we started to get concerned that maybe something might be off.
[narrator] And when a couple has tried for a year with no success,
most health officials consider them infertile.
But one half of the couple tends to get most of the attention.
There is a connection between a woman's stress
and her ability to get pregnant.
[reporter] Fast food could be slowing down how quickly some women become pregnant.
We don't want women to panic, but it is true.
Just go and ask. Don't be scared to ask the question and say,
"Doctor, can you help me figure out what's going on here?"
[narrator] One reason for the focus on women
is that their bodies are the labyrinth.
It keeps changing! What am I supposed to do?
[narrator] The sperm shoots in at around 30 miles an hour,
but sometimes they're doomed from the beginning,
like when the ovaries don't produce an egg,
perhaps because of a hormonal imbalance.
If the ovary does release an egg,
the sperm may not be able to get to it,
because something made the labyrinth impossible...
-like a damaged or blocked tube. -[sperm whimpering]
[narrator] And if the sperm does get to it,
and a fertilized egg travels down
to snuggle into the thick uterine lining,
the lining might be damaged,
so the egg can't stick.
But it isn't just an issue with the labyrinth
that can cause infertility.
In at least 40% of the cases of infertility,
there's a male factor involved.
[narrator] For men,
infertility basically comes down to one thing: sperm.
Chances of conceiving in a given month
go up with sperm count...
till about 40 million.
After that, there's not much extra fertility boost.
And 15 million is a low count,
according to the World Health Organization.
The morphology of a man's sperm,
its size and shape, may also play a role.
This is a normal sperm:
an oval head with a long tail,
while an abnormal sperm may have a weird-looking head...
or two tails.
There's such a variety of normal sperm
and abnormal sperm in any particular ejaculate
that it's really hard to say morphology's a problem.
Poor motility is very important,
but poor motility is always associated with a low count.
So, if the actual numerical count is good-- good enough,
then even a low motility doesn't mean anything.
[narrator] On TV, low sperm count is often treated as a joke,
like the risk posed by hot tubs...
-Mr. Truman. -Yes.
We need to talk about your sperm.
[gasps] I knew it. It's the Jacuzzi at the gym.
He boiled them, didn't he?
[narrator] ...and too-tight underwear...
Look, you gotta help me. I have to get off jockey shorts.
-What, you have a low sperm count? -Very low!
[narrator] ...and excessive masturbation.
Sample hardly had any swimmers.
That's probably from excessive masturbation.
Guy's been outpacing his ability to produce... sperm."
[narrator] Daily ejaculation has no major negative effect
on semen parameters,
as in sperm count or quality.
As for tight underwear...
one study found "semen parameters gradually decreased
while the subjects were in tight conditions,"
but they “gradually increased while they were in loose conditions."
And the "wet heat" of hot tubs can also temporarily lower sperm count.
But only DJ Khaled levels of Jacuzzi time could do that.
For the record, DJ Khaled's sperm seems totally fine.
See? He's got a son.
But some things can cause lasting harm,
like the kind of steroids sometimes used by bodybuilders.
Those steroids build muscle fast because they pump you up
with synthetic forms of testosterone.
And studies have found that heavy long-term use
can cause "some degree of gonadal impairment."
So "the impact on male fertility is not solely a transient condition."
Male fertility can also be permanently impacted
by accidental exposure to chemicals,
like the pesticide dibromochloropropane,
or "DBCP," banned in the US in 1979.
But banana plantations in the Philippines and at least a dozen other countries
still used DBCP well into the '80s.
Thousands of workers were left sterile
and sued the American companies who made and exported the pesticide.
[in Tagalog] After I started working on the banana plantation,
I wasn't able to have kids anymore.
[interviewer] What do you want to happen now?
Since we are claimants against that pesticide,
we want to be paid because of our sterility.
[narrator, in English] The workers in that lawsuit were eventually paid,
depending on how low their sperm count was.
And it's not just men who work with chemicals who are at risk.
Their biologies are being exposed to things
that are not good for male reproductive health.
[narrator] In 2017, researchers reviewed data
from more than 50 countries
and found that the average sperm count has been dropping for decades.
It's still above a totally fertile level,
but the average man today has half the sperm his grandfather did.
So, the other important thing about this is to ask,
"Well, is it getting better?
Is the decline stopping?"
And so we looked at that, and the answer is no.
[narrator] One likely culprit-- plastics.
[dramatic music playing]
Production ramped up during the Second World War...
[man] Here is a plane containing hundreds of plastic parts.
[narrator] ...and it hasn't slowed down since.
[man] Plastic. Plastic. Plastic.
Gradually, there were signs
that maybe everything was not... right.
[narrator] Phthalates are the group of chemicals
that make some plastics soft and flexible.
And another chemical, BPA, is what makes other plastics strong.
They get into our bodies through our food, our skin, and even the air.
And they can change our body's hormonal balance,
which can have an especially huge impact on a developing fetus.
In a six-week-old fetus,
the cells that eventually produce the testes and ovaries,
germ cells, are identical.
In the following weeks, they usually pick a lane,
their development guided by the balance of hormones in the uterus.
In the body, phthalates and BPA can throw off that balance,
potentially impacting the number and quality of eggs that develop
or the testes' ability to produce sperm later.
You can imagine that if you mess
with that critical hormonal development at that time,
you will mess up a lot of systems.
So, I like to think of declining sperm count
as the canary in the coal mine.
Because they represent a disruption that happened very early
that disrupted a lot of things.
[narrator] And the way germ cells develop in the uterus
also explains another huge factor affecting fertility: age.
Male germ cells in the testes don't start producing sperm until puberty.
A germ cell divides into two identical copies.
One keeps dividing,
and those cells become sperm.
But the other stays a germ cell,
so they don't run out.
And a man can produce new sperm until old age.
But in a female fetus,
those germ cells in the ovaries start turning into immature eggs right away.
A 20-week-old fetus has roughly seven million of them.
But they quickly start wasting away.
A female newborn is left with about two million.
And by the time the first one makes its debut in puberty,
she's down to 300,000 or 400,000.
And then every month, one egg is released,
and a thousand or so more die off.
And that's why most women have a much harder time
getting pregnant after 40
and are pretty much out of eggs by the time they're 50.
Age also hurts male fertility, though not as much.
It takes older men longer to get their partners pregnant
especially after they turn 45,
and that's controlling for their partner's age.
But flip through any tabloid magazine,
and you can see they can still have kids.
Sperm production may not stop, but sperm quality can change.
We know there are some terrible, terrible genetic mutation diseases
that, uh, can occur from older sperm,
because we know there's about two mutations
that occur every year.
And so, over time, that builds up and builds up and builds up,
so that there will be more mutations in a 60-year-old's sperm
than in a 20-year-old's sperm.
[narrator] But headlines
about birth defects tend to focus on older women.
There just hasn't been nearly as much research on men.
Male infertility has been poorly understood,
and the public and even doctors don't understand it very well.
Most of the time, the quality of the sperm and the quantity the sperm
is genetically determined.
Now we don't have all the genes figured out, obviously.
They diagnosed it: non-obstructive azoospermia.
Which I had to immediately look up and see what that meant. [laughs]
[narrator] Azoospermia is when there's no sperm in the ejaculate.
Sometimes it's because there's a blockage,
but often, it's because the testes aren't producing
enough sperm to begin with.
That's the case for Myles.
Nothing came back, “You'll never have kids.”
Everything came back, "Oh, there's a chance. There's a chance."
[narrator] Myles had two surgeries
to try to find any sperm that might be in the testes.
But no luck.
It changes a couple when you have an infertility diagnosis.
It takes a toll on you, on your marriage.
[Myles] When you love somebody with all your heart,
but you can't give them what they want...
I was pretty destroyed after the second surgery.
There really isn't a lot of things that treat azoospermia.
[narrator] For centuries,
because fertility research has focused on women,
so have fertility treatments,
figuring out how to get around different obstacles in the labyrinth.
You don't, by any chance,
know the way through this labyrinth, do you?
Who, me? No, I'm just a worm. [chuckles]
[sighs] I have to solve this labyrinth.
[narrator] One shortcut is to let the sperm skip the cervix
by putting them directly into the uterus, called "intrauterine insemination."
Later, scientists developed treatments
that removed more barriers from the labyrinth,
drugs that stimulate the ovaries into producing an egg,
surgery to remove blockages in the Fallopian tubes.
Then in 1978, we figured out how to skip the labyrinth entirely.
[man] You are about to see a historic birth
following in vitro fertilization.
[narrator] The achievement was so historic,
the entire birth was filmed at the British government's request.
[man] Heart sounds and the lung sounds are normal.
-[baby wailing] -[man] Lovely pink color.
Plenty of fat underneath the skin...
Good mature baby.
[narrator] In vitro fertilization comes from the Latin "in glass,"
otherwise known as "IVF."
A doctor retrieves an egg from the ovaries through the vagina
and then mixes it with sperm in a lab.
The fertilized egg is then implanted directly into the uterus.
And another major breakthrough happened in the 1990s:
"Intracytoplasmic sperm injection" or ICSI.
By using a delicate hollow needle,
doctors can now pick up a single sperm and implant it into the egg.
I'm not talking about five million, or 50,000, or 1,000, or 100...
If he has two or three sperm or one sperm, we can find it,
and we can inject it directly into the egg,
and you have a normal pregnancy rate.
[narrator] We'd gotten around the labyrinth,
but a couple still needs to find that sperm.
Give me the child.
I figured there had to be a way somehow.
So, I had done research from the start.
[narrator] And she came across a less common procedure,
which could potentially locate sperm
that the other surgeries might have missed.
She's like, "It's gonna be $13,000, and it's a maybe,
and we've already been told no twice."
And I was like, "Wow."
I knew, at this point, it was the last hurrah.
If-- If we got bad news, that-- that was it.
But, um, you know just, I'm also, like, the epitome of optimism.
So, I was like, "Oh, yeah, we'll figure it out. This is gonna work."
[narrator] All this technology also opens up the possibility
of biological parenthood for couples where both partners have eggs
or both partners have sperm, and for people without a partner.
A changing face of parenthood is emerging
as more women are using in vitro fertilization
to become single mothers.
Joseph Tito's journey to fatherhood via surrogacy in Kenya
is drawing attention to the diverse ways
in which people may choose to have children.
We're able to take the eggs from one woman,
fertilize them with the donor's sperm,
and transfer them into her same-sex female partner.
We both participated in our own ways in creating her.
This is Zachary. This is David,
and we are very happy to be here.
-[man] Hey! -Hey, Zachary.
[narrator] But the new tech doesn't come with a guarantee.
For example, IVF's success depends a lot on the age of the eggs.
For women under 35, it works 29% of the time.
For women 40 to 42, the success rate is around one in ten.
The chance of success goes up when using eggs frozen at a younger age.
But according to one study,
the real way to maximize the chance of success is to freeze a ton of eggs.
For most women, 40,
which would usually require several rounds of egg extraction
and months of hormone injections, which can take a physical toll.
Though you may not know that looking at ads on social media,
from boutique startups urging women in their 20s
to freeze their eggs as an insurance policy.
One compared egg freezing to the cost of an acai bowl,
as if the procedure was as easy to buy into as any wellness trend.
I think it's unfortunate that it's become commercialized.
So, there's a lot of really kind of atrocious marketing going on.
Because it's not a guarantee of anything.
[narrator] But there's a new promising therapy
that could help even more women transcend their biological clocks:
not freezing their eggs, but freezing a piece of their ovaries.
[machine whirring]
[narrator] This was originally developed for cancer patients,
whose ovaries can be destroyed by chemotherapy or other treatments.
So, we freeze the ovarian tissue, and within a matter of days,
they can start on their cancer treatment. And then 20 years later...
[narrator] The tissue is transplanted onto the dead ovary,
where incredibly, the transplanted tissue
starts functioning like its own new ovary.
And lo and behold, they start ovulating,
and they get pregnant spontaneously with no IVF.
[narrator] As of 2016,
84 babies had been born through ovarian tissue freezing,
two-thirds without IVF.
And doctors hope that one day this could be a mainstream therapy.
And while each new technology
is helping more and more people conceive who couldn't before,
some are always left out.
As a black lesbian woman who desperately wants to be a mother,
I've had to look at, like, "What does insurance provide?"
How much money is this going to cost? How accessible is this really for me?"
[narrator] In most countries,
a single round of IVF will run thousands of dollars,
and many people need multiple rounds for it to work.
It's a very expensive procedure,
and we're talking about black women only making 64 cents on the dollar.
[narrator] And some countries can ban certain groups from getting IVF
or other fertility treatments.
Because these aren't just medical procedures,
they challenge the traditional idea of family.
Remember, health officials have long defined infertility
as an inability to get pregnant after one year of unprotected sex,
which obviously doesn't apply to single women
or a lot of the LGBTQ couples.
[in French] The route for single women in France is an obstacle course.
We're not accommodated because it's been illegal up until now.
And you have to go abroad. You have to research a clinic.
[narrator, in English] In 2017, some doctors changed the definition
to an impairment of a person's capacity to reproduce
either as an individual or with his or her partner."
Which may lead the way to broader access to treatments.
And no doubt, more research and new discoveries will offer hope
to more people who long for a biological child.
We had a bottle of champagne in the fridge if the news was good,
uh, and we probably just would have smashed it
on the floor if the news was bad.
So, we get the call from the doctor,
and he literally just said, "Hey, you know, how have you guys been?"
And then it was, "I got some good news for you."
And we both fell to the floor in tears. I don't--
I mean, it was just...
it was probably one of the best moments of my entire life.
We still have a very long road ahead of us with IVF and everything.
And, um, we're hoping to have our finances in place
to go out in October and hopefully get pregnant.
-September. -September.
[both chuckle]
[theme music playing]