Beijing has announced a slew of perks to encourage families to have more babies, as the birth rate hit a record low and officials warned that the population will start to shrink by 2025.

The world's most populous country has been grappling with a looming demographic crisis as it faces a rapidly ageing workforce and its weakest population growth in decades.

Although Beijing ended its "one-child rule" in 2016 and last year allowed couples to have three children, the birth rate has slipped over the past five years.

The policy guidelines issued by the National Health Commission on Tuesday urge central and provincial governments to increase spending on reproductive health and improve childcare services nationwide.

They require local governments to "implement active fertility support measures", including offering subsidies, tax rebates, and better health insurance, as well as education, housing and employment support for young families.

All provinces must ensure they provide enough nurseries for children aged two to three by the end of the year to reduce a shortage of childcare services.

The commission also said it would carry out reproductive health promotion to enhance public awareness while "preventing unintended pregnancy and reducing abortions that are not medically necessary".

Richer Chinese cities have been doling out tax and housing credits, educational benefits and even cash incentives to encourage women to have more children, and the latest guidelines seek to push all provinces to roll out such measures.

The birth rate slipped to 7.52 births per 1,000 people last year – the lowest since records began in 1949 – according to National Bureau of Statistics data.

Higher costs of living and a cultural shift as people grow used to smaller families have been cited as reasons behind the lower number of babies.

China's population will begin to shrink by 2025, health officials warned earlier this month. (Agencies)