JUST as Soviet planners periodically reviewed their quotas for grain production, so too has China updated its policy on baby-making: all Chinese couples will soon be allowed to have two children, not just one.

The change, brought about in part due to worries about an ageing population and a shrinking workforce, will be welcome news for many urban couples who want a second child but are currently barred from having one. And it represents a slight loosening of one of the most intrusive and oppressive social policies ever devised. But it will have only a modest impact on China’s birth rate (see chart).

Previous moves to relax the one-child policy have only slightly affected fertility. In 2000 the Communist Party allowed couples to have two children if both parents were themselves only children. In Guangzhou city some 14,000 couples were eligible. They produced only 360 additional babies in 2009, according to researchers at Credit Suisse. Henan province implemented this policy in 2011. In the following two years, Henan’s parents popped out just 600 extra babies.

In recent years China has seen about 16m births annually. Credit Suisse estimates that the latest reform of the one-child policy will lead to an extra 1.2m babies in 2016 and a total of some 7m by the end of the decade—about half a Shanghai. Many Chinese couples, like parents elsewhere, calculate that having more children would mean educating them less expensively. Moreover, some couples who would have wanted a second child have already been sterilised.