Many are aware that fertility declines as you age

so when should you have kids,

and is there anything you can do to beat your biological clock?

A woman's first period is generally around age twelve or thirteen,

but most ovaries don't start releasing eggs until a few years after this

In fact, a woman's peak fertility

isn't actually until her early or mid twenties

Unlike males who are constantly producing new sperm

females have a finite number of eggs, but don't worry

By puberty you have around 300,000

way more than the 300 to 400 you will release in your lifetime

However popular statistics show that after trying to conceive for one year,

A thirty-year-old woman has a 25% chance

of not conceiving a life birth

This increases to a 44% chance at 35,

and 66% chance at 40 years old

But most of this data comes from a 2004 journal

looking at French birth records from 1670 to 1830

it's safe to say that a lot has changed

for the lives and health of women since before the age

of electricity, antibiotics, and reliable food supply.

It also does an account for the amount of sex

couples were having and the fact that sex drive tapers off as you age.

Modern studies present a more optimistic look

with the percentage of women unable to conceive

within a year of unprotected intercourse at 13% to 14%

for women aged 27 to 34

and 18% for women aged 35 to 39.

Still showing declining fertility but much better odds

than the historical data suggest. Another study found that among

38 and 39 year olds who have been pregnant before

80% were able to become pregnant naturally within

six months. And this points to another flaw in the studies

Nearly half of all pregnancies in America are

unintended. This means highly fertile women are more

likely to become pregnant accidentally when they're younger,

while those purposefully trying to have kids for the first time

in their late thirties are already disproportionately

less fertile regardless of age creating an overestimate

for the effect of biological aging.

However, older eggs may not fertilize normally and there is an increase

of chromosomal abnormalities with age. A woman who is

thirty has a 1 in 800 chance of having a baby with

Down Syndrome, but the probability goes up to 1 in 100

when she's forty. Granted, that's still only

a 1% chance. But what about men? Many assume

male fertility is limitless with some famous examples like

Charlie Chaplin having kids up until his seventies.

And while men do continually make new sperm, the more cell divides

the higher probability of genetic mutations.

By the time a man reaches 50, the cells that create his sperm

have gone through over 800 rounds of division and replication.

As a result, older fathers carry increased

risk of children with schizophrenia, autism, cancer

a form of dwarfism, neurofibromatosis, and even skull and

facial abnormalities. On top of this, even among young men

in the Western world, sperm counts have dropped over 50%

in the last 40 years

The impact and importance of this

is yet to be determined though

Of course, there's more to raising children than biology

anecdotal accounts points to younger parents having more energy, but

older parents having more maturity and financial stability.

Of course, more income does not mean better parents

but research has shown that higher family income is linked to higher

SAT scores. Not to mention in low to middle

income countries the risk of death per birth for women between

15 to 19 years old is 28% higher

than for women 20 to 24 years old. Studies have

also found that in some Sub-Saharan African countries

Up to 25% of girls and young women drop out of school

because of unintended pregnancies.

Preserving young female eggs by cryogenically freezing them

has also become more common but isn't a guarantee

with increasing age still affecting pregnancy success rates

and researchers finding that the freezing process degrades

the quality of the eggs. Additionally, this isn't a viable

option for most women, as the cost of freezing alone

is 10,000 dollars, and one round of in vitro fertilization

can cost upwards of 12,000 dollars.

Overall, yes, conceiving a baby becomes more difficult

as both men and women age, but it is not the level of

baby panic that is so often discussed in the media.

Individual fertility is very variable

based on genetics and lifestyle, and the best time to have kids

is a very personal decision as is having kids at all.

Special thanks to the Bill and Melinda Gates Foundation for supporting this episode.

Even though the world is on an incredible path of progress,

it's important to remember that progress isn't inevitable.

That's why the Gates Foundation has created a Goalkeepers Report

which will help raise awareness, accountability, and drive action

for a better future.

Did you know that the number of mothers who die during childbirth

has been halved in the past generation?

The Gates Foundation wants to ensure continued healthy lives

and promote well-being for all ages.

Click the link in the description to read the report and see the progress being made.

And subscribe for more weekly science videos every Thursday!