BEIJING (BLOOMBERG) - China's smaller cities are struggling to cope with a baby boom after the nation ended its one-child policy in 2015, demonstrating that it's too early to further relax the new two-child ceiling, according to lawmaker Sun Xiaomei.

Sun criticized calls for an immediate easing of the current two-child policy, and said her visits to small cities and towns showed her that already-stretched hospitals, paediatricians and kindergartens are finding it hard to cope with increased births.

In one district of the western Sichuan province, a vaccination centre that Sun visited was so crowded she wasn't able to enter.

In Ulan Hot in Inner Mongolia, a hospital didn't have mobile beds to move women from the labour ward, and used wooden stretchers instead, she said.

Demographers and others calling for an immediate lift of the two-child rule need to "go to the smaller cities, go to check out the hospitals," Sun, a professor at China Women's University in Beijing, said in an interview on the sidelines of the annual National People's Congress meeting last week.

"They probably draw conclusions simply from what's happening in the big cities. Things are not as they have imagined."

Sun is at odds with an increasing number of academics who say the introduction of a two-child policy is too little, too late to address the nation's ageing population and shrinking workforce.

The working-age population has been declining since 2012, threatening the competitiveness of the export sector as wages rise.

The economy's dynamism is also under threat, as the share of young people shrinks.

That's prompted demographers including Cai Fang, a member of the Standing Committee of the NPC, to call for China to allow three or more children and urge the government to roll out incentives to encourage more births.

Government officials are considering subsidies for couples who have a second child to help increase the birthrate, according to state media.

But a deeply entrenched preference for smaller families after decades of the one-child policy, as well as high child-rearing costs in big cities, has prevented the boom from taking hold everywhere.

After announcing the nationwide two-child rule in October 2015, officials estimated an increase of four million additional births a year through 2020.

Last year, births increased by just 1.31 million from a year earlier to 17.86 million.

"You can't extend a bad policy simply because there aren't enough resources," said Li Wei, a member of Chinese People's Political Consultative Conference. "Even a full lift of the restrictions right now isn't soon enough to rescue the nation from a population collapse."

Li, 63, was a mayor in Jiangmen, a city in Guangdong province, for 12 years, and says he saw how it became more and more difficult for factories to hire workers.

"Without labour, how can we develop the economy?" he said. "We should not only lift curbs on child births, we should encourage them right now."

But Sun says a disproportionate burden is falling on the nation's smaller cities and towns, where parents are more inclined to have a second child because living costs - and the pressure of life generally - are lower.

In such places medical and education facilities are strained to breaking point, she said.

Parents have to make appointments and wait for days to vaccinate their children at a congested clinic in Sichuan's Pidu county, a district of half a million people, Sun said.

In Ulan Hot, the local government recently reassigned a building to the city's maternal and child care hospital to help cope with an overflow of women in labour, she said. A shortage of paediatricians can't be turned around quickly because it takes seven years to train one, she noted.

Sun, who studied the history of women's movements in college and worked at the women's federation for more than three decades, expects birth planning policies to be fully lifted eventually.

Before then the most effective way to boost the fertility rate is to build additional hospitals, train more obstetricians, subsidize child-care facilities and offer tax breaks to families with more children, she said.

"When we have solved all those problems, we'll eventually lift all restrictions," Sun said. "We probably should wait five years to see the result."