Life expectancy at birth (e0) forecasts are used to estimate future pension costs. Previous French official forecasts have often overestimated e0. Recent forecasts published by demographers provide higher e0 estimates than official forecasts for France, Sweden, Japan and the USA, and do not consider that e0 could decrease, as in previous years because of flus, heatwaves, or other outbreaks. Too optimistic forecasts make that governments may overestimate future pension needs.