In 1977, for the very first time,
a team of British researchers
successfully fertilized a human
egg in a dish and transplanted
the embryo into the mother's body.
The mother gave birth to a baby
named Louise Brown, who is now almost
40 years old. The doctor who pioneered
the procedure won a Nobel
Prize for it, in 2010. That
procedure is now known as "in vitro
fertilization" or "IVF".
But a lot has changed since Louise
was born. By studying IVF for the past
few decades, scientists have made it
a lot more effective, with fewer
complications and better success
rates. There are all kinds of reasons
why two people might have trouble conceiving
naturally. Like low sperm
count or poor quality eggs.
The basic procedure involves a few
main steps.
As you might have guessed from the name Gonado-
-tropins affect the gonads, controlling
sex hormone levels and egg and sperm production.
Ovarian hyperstimulation stops
the natural menstrual cycle and
causes the ovaries to form multiple
follicles. With all theose follicles
Lots of eggs can be collected at once,
usually between 15 and 30.
Way more than the single egg
that's released in a natural cycle. Once
the follicles have formed, doctors give an
injection of a hormone called "Human
Chorionic Gonadotropin"
which makes the eggs mature. Then,
they collect the eggs and incubate them
with sperm in a special solution. Once
the eggs are fertilized, they're grown in a
dish for a few days as they start dividing.
Doctors choose the embryos that look
the best for implantation and
implant them directly into the uterus
through the cervix. A lot of the time, they'll
implant several embryos at once
to increase the chances that one of
them will attach to the uterine lining and
grow. Since the 1970's, researchers
have been working on advancing the science and
technology behind IVF
to lead to more healthy pregnancies.
A different process called Natural IVF
avoids some of the side affects of the
extra hormones. Doctors just harvest
naturally released eggs, but
there's a down side. Only one egg can
be collected at a time. And since IVF
doesn't have a 100% success
rate, patients often have to go
through the procedure many times.
Instead, Doctors can balance ovarian
hyperstimulation and natural
IVF in a process called Mild IVF.
Researchers have also been working on the problem
of multiple births. One big
criticism of IVF treatments is that
it often results in twins, or
triplets, or even more and that's
a lot of babies. More than
most people are prepared for. Multiple
births are so common because doctors tend
to transplant a bunch of embryos
since many of them don't make it. At least until recently.
In a natural pregnancy embryos
in this cleavage stage would still be
in the Fallopian Tube, between the
ovary and the uterus. But, with IVF
we stick them straight into the uterus.
It is tough for the 3-day old embryos
to survive in their, so only
about a quarter of those embryos lead
to pregnancies. Doctors transplant
more of them, to give a patient a
decent chance of at least one surviving.
Except that sometimes, they get
lucky and end up with more than one.
But now we know what conditions to use
to grow embryos for longer
up to 6 days, into the Blastocyst
stage. That's when the embryo
hallows out as its dividing cells
start to specialize, so they can eventually
become things like heart cells and
lung cells. By the time the get to the Blastocyst
stage, many of the embryos
that wouldn't have been able to survive in the
uterus, have already broken down. So,
almost half of the embryos implanted
at this stage, lead to pregnancy
So there is less risk of quadruplets
or octuplets. Researchers have
also figured out how to keep people from
passing on mitochondrial diseases
when the mother has a mutation
in the special kind of DNA that lives in the
mitochondria. They take the egg's
cytoplasm, so all that watery stuff,
outside of the nucleus and replace it
with a third donor's. Which means
that technically babies conceived this way
end up with 3 parents. So,
with IVF lots of people
who may not have been able to conceive a
child on their own, are now parents.
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