It’s the Lebanese, Pakistanis and Samoans doing the heavy lifting, producing between three and four babies for every mother. After a baby bump following Peter Costello’s famous call to arms for Australians to “have one for mum, one for dad and one for the country”, the fertility rate has ebbed by 9 per cent since 2011. Sydney’s fertility rate is now the lowest of any capital city in the country, tumbling by 15 per cent over the past six years. It is well short of the natural replacement level, meaning Sydney’s overall population would fall without immigrants. Melbourne’s fertility rate is the second lowest of the nation’s capitals, having fallen by 4 per cent over the past six years. Like Sydney, without migrants Melbourne’s overall population would be falling.

Where the babies are Sydney’s inner city is a baby desert. The Sydney-Haymarket-Rocks area is home to almost 31,000 residents. They had just 254 babies between them last year. Other baby-free zones include Potts Point, Woolloomooloo, Darlinghurst, Redfern and Surry Hills. Baby hot-spots are in the city’s south and west. Lakemba (fertility rate of 2.93), Wiley Park, Bankstown South and Lethbridge Park have the highest fertility rates in Sydney.

The biggest drop in fertility in Sydney has been among women aged between 20 and 24, falling by more than a quarter since 2011. At the same time there has been a sharp drop in the teenage birth rate which has fallen by 42 per cent. Young people no longer have the confidence society is providing a setting for them to have enough children to reproduce existing population. Demographer Bob Birrell But some parts of the community continue to start their families young. Lebanese-born women in their early 20s have a fertility rate almost six times that of Australian-born women. It’s not just women in their early 20s. Sydney’s overall fertility rate among women aged between 25 and 29 has dropped 16.4 per cent over the past six years and by 7.6 per cent among those in their early 30s.

Australia’s often divisive population debate, thrust back into the spotlight again last week at the Council of Australian Governments meeting, mainly focuses on the headline permanent migration figure and the failure of infrastructure to keep up. Scott Morrison with state and territory leaders at COAG on Wednesday. Credit:AAP But the reality is that, without the babies of migrants who now call Australia home, the population would soon be shrinking. The comparison with New Zealand is striking. The Kiwi fertility rate is 2.14 - enough to replace New Zealanders already in the country - compared with the Aussie rate that is 0.34 babies short of replacing every mother and father. Economic forces behind fertility slump

“What sort of society can’t create the circumstances to reproduce itself?” veteran demographer Bob Birrell said. “That is an affront. It implies that young people no longer have the confidence that their society is providing a setting for them to have enough children to reproduce existing population.” Cultural change has played a role, but Mr Birrell believes the shift is fundamentally economic. “The younger age group 25-34 dropping like a stone,” he said. “There will be some compensation as they reach their late 30s which that perhaps reverse some of the trend, but births delayed ultimately add up to births cancelled.”

Australian Population Research Institute Data shows that the proportion of young couples aged 30-34 who are renting in Sydney and Melbourne has gone up five percentage points since 2010 on the back of soaring house prices that have only just started to cool. “It’s very difficult for couples who want to raise children to find a family friendly dwelling which would allow them to get on with the business of raising a family,” he said. “There is a very clear correlation and causation.” Grace City Church pastor and father of two Hew Nunn and his Iranian-born wife Cindy are among them. “It’s just financial, we can’t afford to have more,” Mr Nunn said. “We've been married for four years. We have two kids, we are renting. If we go to three, you need a bigger car and you need a bigger bedroom.

“The dream of having the yard and [quater-acre] block is long gone really.” Loading Nationally, the number of children born across the country fell in 2017, down by 1962 on the 311,104 who arrived in 2016. While NSW bucked the trend it wasn’t enough to offset some large falls in other parts of Australia including a 931 drop in Western Australia. The falls are set to exacerbate what is already looming a major labour market problem. A recent a study by Shah and Dixon shows there will be 4.1 million new job openings in Australia between 2017 and 2024.