Sex: A Horizon Guide Page #6

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the treatment of infertility.

Researchers removed eggs

from the mother

and combined them with sperm

from the father in a Petri dish.

The embryologists could then check

to see if the embryo's development

was proceeding normally

before re-implanting

only the most healthy embryos

back into the mother,

for nature to take its course.

The technical name for the procedure

is in vitro fertilisation,

or IVF.

The media coined the phrase

"test-tube babies".

At the time, it was

highly controversial.

Since those early days, hundreds

of thousands of healthy babies

have started their lives

in this way,

and the stigma has gone.

It's one of science's

greatest success stories.

But the moral dilemmas thrown up

by test-tube babies didn't vanish.

People began to worry that

the technique gave scientists

the opportunity

to do far more than simply helping

infertile couples have babies.

IVF meant that it one day

might be possible

to tamper with the DNA

of an embryo in the lab

and create a bespoke baby.

30 years ago, Horizon made a drama

where families were no longer

prepared to leave the appearance

and character of their children

to chance.

You've got two girls - are you

certain you don't want a boy?

Yes, quite sure - we really do

want another girl. Yes, definitely.

Right. Well, you've had a chance

to view the data at home?

Yes. We've narrowed it down

to zygote 3 and 6 -

we're not really sure

which one to choose.

What sort of characteristics

were you thinking of?

We definitely don't want to tamper

with the physical side of things

in any way. No, except that

we would like her to have

my father's red hair.

Ah. Ah, well, that's easy.

We can make her homozygous

on the three hair colour genes.

What about her character

and emotions? Ah, well, yes,

there are a few things we'd like

to have modified if possible.

We'd like to reduce shyness,

and susceptibility to depression...

..without necessarily damaging...

any artistic potential.

Also, we'd like her to be musical,

and if possible,

also we want her to be ambitious.

A world where we could pre-order

genetic traits for our children

might seem fanciful,

but in some ways,

it's already here.

IVF has given embryologists

the opportunity to screen embryos

for genetic problems.

These techniques have helped women

like Philippa Handyside,

for whom having children

was impossible.

Just kept miscarrying all the time.

And it just actually got quite normal

- that was actually how awful it was.

It was very hard,

and it sounds really harsh,

but you just kind of get...

It just becomes part of life.

I used to get pregnant, lose it,

pregnant, lose it, and that was it.

Philippa Handyside wasn't trying

to create the perfect child -

she just wanted to have a baby.

But she wasn't having any luck.

So she underwent testing to see why

she was having so many miscarriages.

The cause of her miscarriages

was genetic -

the result of a chromosome disorder.

It meant most of her embryos didn't

have the right combination of genes

they needed to grow healthily.

There was nothing Philippa's

local hospital could do for her -

it seemed she might never

have children.

But then, Philippa

heard about a new technique.

It's a technique some people think

could lead to designer babies.

The technique is called

preimplantation genetic diagnosis,

or PGD.

Using PGD, scientists can

screen embryos outside the womb,

long before they develop

into babies.

Then, they can select just those

embryos that carry healthy genes

to ensure the baby is free

from genetic abnormalities.

PGD is one of those ideas

that's so clever

that it seems impossible to do.

I mean, how could you possibly

take a very early embryo and

take out a cell and diagnose it?

Well, in the end,

it transpired that the embryo

is such a tough little beast

that it actually allows you to do

fairly outrageous things to it,

without noticing.

To do PGD, the doctors first

had to extract eggs

from Philippa's ovaries.

These eggs were then fertilised

by her husband's sperm in a lab.

The fertilised eggs were allowed

to develop into a cluster of cells.

You phone every day and you're

told how they're getting on.

It's like having children

in nursery - you're told every day

how they're progressing through.

Then, 48 hours after fertilisation,

acid was used to etch a hole

in the membrane of each embryo,

and a single cell sucked out.

And on day three

after their collection,

we've taken a single cell

from each embryo,

and we've sent those cells to

our genetics team across the road,

so they can make

the molecular diagnosis.

The theory is that if the analysis

shows the genes are normal

in the single cell,

then the embryo is came from

will also be genetically normal.

That's OK - two blue...

Two green,

two red, so that's fine.

Eventually, they found cells

from two of Philippa's embryos

that had healthy genes.

They called us through and said,

"Yep, we've got a couple."

The geneticist said,

"There's one that...

it's not divided so well,

"but the other one, brilliant,

absolutely brilliant.

"So, we're going to implant,

if you're happy, two back in."

So, it was a case of,

get ready, and get kind of...

into the room, and ready to

have the implantation...done.

PGD allows mothers like Philippa

to have children they would

otherwise have been denied.

But there are those who still worry

that this is the thin end

of the wedge,

and that in the future, people

would be able to select embryos

on the basis of much more

controversial genetic traits.

The forefront of research

into sex and fertility

continues to present us

with much trickier ethical problems

then we've ever had to grapple with

in the past.

But at the same time,

the science of sex

has helped us learn about ourselves,

to combat sexual problems

and to restore fertility.

Sex is still the most intimate

and personal aspect of our lives.

But since science

got into bed with us,

we've had a much better chance

of decoding this tricky subject,

and of understanding ourselves.

We know so much more about sex now

than we did just a few decades ago,

and I think our lives

are better for it.

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