China will ease family planning restrictions to allow all couples to have two children after decades of the strict one-child policy, the ruling Communist Party said on Thursday, a move aimed at alleviating demographic strains on the economy. The policy is a major liberalisation of the country’s family planning restrictions, already eased in late 2013 when Beijing said it would allow more families to have two children when the parents met certain conditions. Watch: Chinese welcome new two-child policy A growing number of scholars had urged the government to reform the rules, introduced in the late 1970s to prevent population growth spiralling out of control, but now regarded as outdated and responsible for shrinking China’s labour pool. READ MORE: What to expect when everyone's expecting: Beijing hospitals urge pregnant mothers to book beds quickly as city braces for baby boom For the first time in decades the working age population fell in 2012, and China, the world’s most populous nation, could be the first country in the world to get old before it gets rich. The announcement was made at the close of the key fifth plenum, where party elites are deliberating and endorsing the next five-year programme on China's social and economic policies. China will “fully implement a policy of allowing each couple to have two children as an active response to an ageing population”, the party said in a statement carried by the official Xinhua news agency. There were no immediate details on the new policy or a timeframe for implementation. READ MORE: How one-child policy plucked a girl from China to US and gave her undreamt-of opportunities Wang Feng, a leading expert on demographic and social change in China, called the move a “historic event” that would change the world but said the challenges of the nation’s ageing society would remain. “It’s an event that we have been waiting for for a generation, but it is one we have had to wait much too long for,” Wang said. “It won’t have any impact on the issue of the ageing society, but it will change the character of many young families.” Under the 2013 reform, couples in which one parent is an only child were allowed to have a second child. HOW IT HAPPENED: China legislators vote to end labour camps, back change to one-child policy Critics said the relaxation of rules was too little, too late to redress substantial negative effects of the one-child policy on the economy and society. Many couples who were allowed another child under the 2013 rules decided not to, especially in the cities, citing the cost of bringing up children in an increasingly expensive country. State media said in January that out of about 30,000 eligible families in Beijing, just 6.7 per cent applied to have a second child. The Beijing government had said last year that it expected an extra 54,200 births annually as a result of the change in rules. Watch: China's extra kids mean business Chinese people took to the microblogging site Weibo, to welcome the move, but many said they probably wouldn’t opt for a second child. “I can’t even afford to raise one, let alone two,” wrote one user. Couples who flout family planning laws in mainland China are, at minimum, fined, some lose their jobs, and in some cases mothers are forced to abort their babies or be sterilised. William Nee, a China researcher at human rights campaign group Amnesty International, urged the leadership to go further. LOOKING BACK: China slaps largest one-child policy fine, 7.5 million yuan, against director Zhang Yimou “China should immediately and completely end its control over people’s decisions to have children. This would not only be good for improving human rights, but would also make sense given the stark demographic challenges that lie ahead,” he said. China should immediately and completely end its control over people’s decisions to have children William Nee, Amnesty International The fifth plenary session of the 18th Central Committee of the party also endorsed a new five-year economic plan at a time when the world’s second-largest economy is trying to adjust itself to a “new normal” of slower growth. The next plan, covering 2016 to 2020, is the first to have been crafted under the leadership of Xi Jinping that will aim for “medium-high” growth during the period. During the closed-door meeting, about 200 members of the party’s Central Committee were expected to discuss how best to achieve its goal of building a “moderately prosperous society” by 2020. This involves doubling its 2010 gross domestic product and per capita income by 2020. To realise both goals, economists have said China needs to keep its GDP growth at least around 6.5 per cent on average for the next five years. The conclave also endorsed earlier decisions to strip the party membership of Ling Jihua, a one-time top aide to former president Hu Jintao, and nine other former officials.