The dreaded 'body-clock' - how aging affects our chances of having children

When the talk of children surfaces, the dreaded phrase "body-clock" is never far behind. But how does aging affect the process of conception?

The chance of having a baby each month you try is 22 percent aged 30 - then it's all downhill.

At 35 years old its 16 percent, and by the time you're 42 your chances sit at 3 percent.

It's a commonly known fact that older women will have trouble conceiving - but according to fertility specialists; it's not just women that contribute to the difficulty

"We used to think, it didn't matter how old your bloke was. We now realise that guys do drop off," said fertility specialist Dr Mary Birdsall on Friday nights The Project.

"Sperm quality does decrease," said Dr Guy Gudex. "The quality on average starts to decline at age 45."

But that's not the only concern.

"We see an increased risk of things like schizophrenia in the offspring of older guys," said Dr Birdsall.

But older women will struggle too - women are born with a finite number of eggs, and these begin to decline after women get their first period.

"From puberty, through to menopause you go from a million eggs, down to almost none," said Dr Gudex.

Older eggs also don't work as well as younger eggs - leading to an increased risk of miscarriage.

Dr Birdsall had some advice for women who are worried about their reproductive future.

"I would do a blood test, in my mid-twenties called an AMH, and that would let me know when my menopause was going to be and how long I had to have babies, and then I'd plan accordingly."

Watch the full interview above.