See what a high band reads like.

P1Across much of the developed world, couples are electing to raise far fewer children than their parents and grandparents did. The drivers of this shift are readily identifiable, and its repercussions for society are profound.

P2Several forces converge to depress birth rates. Foremost among them is financial strain: the spiralling costs of housing, childcare and education have turned a large family into a luxury that many simply cannot contemplate. A second, equally powerful, cause is the transformed position of women, who now invest years in higher education and demanding careers and consequently postpone motherhood, which naturally compresses family size. Reliable contraception, together with a cultural reorientation that prizes autonomy and self-fulfilment over tradition, entrenches the same tendency.

P3The consequences are wide-ranging, and by no means uniformly bleak. On the credit side, smaller families enable parents to lavish greater time and resources on each child, while gentler population growth relieves pressure on housing stock and ecosystems alike. The graver concern, however, is demographic. As fertility falls, societies age, leaving a contracting workforce to shoulder the pensions and healthcare of a swelling cohort of retirees. This imbalance threatens to throttle economic growth and to overwhelm care systems, a predicament already painfully evident in Japan and South Korea, where policymakers wrestle with shrinking labour forces and unsustainable welfare commitments.