Buoyed by the improving COVID-19 situation in NSW last year, Samantha and her husband of over 10 years decided it was time a third set of tiny feet was running around their home.

But with Sydney and its surrounds cast under the shadow of another virus outbreak in December, the Central Coast couple made the difficult decision to put their plans on ice.

"This isn't a decision that we want to make," she told AAP.

"It is really hard. We really want another baby."

It's not the virus itself that scares the pair, but rather its impacts on the nation's economy and health system.

"It's only now that we're in January 2021 and it's all happening all over again that we realised that this is probably not over anytime soon," she said.

"What's going to happen with our jobs?

"Is our mortgage going to be safe?

"What if there are restrictions and the father is not allowed at the birth?

"If we are successful and fall pregnant again, are we just putting more stress on ourselves at an already uncertain time?"

The pair have vowed to reassess the situation each month, but predict they're in for quite the wait.

And at 34, Samantha knows that may mean baby number three never arrives.

"We've definitely prepared ourselves that this might be it ... we might just have to accept that we won't try again," she said.

But Samantha is far from alone.

Demographer Dr Liz Allen says many would-be parents will have put off their plans to create or expand families in 2020.

"Being stuck at home with a partner doesn't meet the necessary ingredients for increased fertility rates," the population statistics expert told AAP.

"More sex is insufficient for a baby boom to occur."

Fewer opportunities to meet people coupled with economic uncertainty means people will likely delay or forgo having children during this period, she says.

"People have lost their jobs and lost access to things like parenting leave.

"We've also seen difficulties in having basic needs met, like buying toilet paper and pasta.

"This all has a psychological impact on people and their feelings of insecurity and hope for the future."

Low fertility rates in 2020 would add to a long streak.

Australian Bureau of Statistics data released in December showed the total fertility rate had declined to a low never seen in Australia's official national statistics.

The measure, which indicates the average lifetime number of births per woman, fell to 1.66.

Is that a problem? The answer is hotly contested.

Dr Allen says it is, but not yet.

With the birth rate below population replacement levels, as it has been since around the mid-1970s, Dr Allen says Australia is facing an ageing population crisis.

"How will the nation continue to be economically strong and maintain a level of socio-economic wellbeing if there are fewer relative contributors to government coffers?"

Young people are really getting a raw deal, she says, with the pandemic only adding to the uncertainty.

"The nation wants young people to be the economic lifeline ensuring the country's future. But at the same time these pressures added to existing generational inequalities might mean that young generations won't accomplish the things we take for granted: secure housing, secure careers, and family."

But former South Australia politician Sandra Kanck says lower birth rates are exactly what Australia - and the planet - needs.

Now the president of Sustainable Population Australia Ms Kanck says there is no depopulation or ageing population crisis.

"Even if we had zero net migration, our population would continue to grow in size slowly until around 2045," she said.

Australian Associated Press