WHAT links Ireland with Venezuela, Somalia and Afghanistan? All four countries forbid abortions, except to save the mother’s life. Ireland’s eighth constitutional amendment, which 67% of people voted for in 1983, prohibits terminations even in rape cases. Yet that could change soon. On May 25th Ireland will hold a referendum on whether to repeal the amendment, thus allowing parliament to legalise abortion. Polls suggest that half the population favour doing so, with 30% disagreeing and 20% unsure.

Statistical analysis of global abortion rules reveals that almost no rich country has a greater mismatch between its law and its demographic profile than Ireland. True, a large Catholic contingent and high levels of piety are both associated with stricter rules. But a hefty GDP per head and high rates of women working are linked to greater laxity (as is a history of communist government, notes Jessica Hyne of the UN). Overall, Ireland resembles Austria or Spain, which both allow abortion on demand.

The analysis identifies other rich countries that one might expect to have looser laws. New Zealand and South Korea both forbid abortion on demand; both are considering a change. Poland is another European example with stricter legislation than its demography would predict. The socially conservative Law and Justice (PiS) party is trying to impose even tougher laws, similar to Ireland’s.