FURTHER delays in childbearing could lower France’s recorded fertility rate through 2040, even if postponed births eventually take place, a new scenario analysis suggests.
The research separates the effects of having children later from the possibility that some delayed births never occur. Its findings highlight why a fall in annual fertility indicators does not necessarily mean an equivalent reduction in the number of children women ultimately have.
Delayed childbearing is an increasingly important reproductive health issue and beyond its effect on period fertility, postponement shifts childbearing towards ages at which natural ability to conceive declines.
Researchers therefore set out to quantify how further delays in childbearing could affect fertility in France up to 2040, separating births that happen later from those that might never occur.
To do so, they used France’s official 2026 INSEE central population projection to examine births between 2026 and 2040.
Researchers tested four levels of further delay in childbearing: none, half, equal to, or 1.5 times the rate at which average maternal age rose between 2014 and 2025.
During that period, average maternal age increased by about one month each year. These additional delays were applied to France’s official projection, which already accounted for later childbearing and declining fertility.
For each scenario, researchers assumed either that all delayed births eventually occurred or that 3% fewer occurred for each additional year of delay. The 3% reduction was an illustrative assumption, not an observed finding in French women.
In the reference projection, the total fertility rate in 2040 was 1.450. Under benchmark additional postponement, this fell to 1.327 when all delayed births were eventually retained, and 1.283 when incomplete recuperation was assumed.
At one-and-a-half times the benchmark delay, the corresponding rates were 1.273 and 1.212. These figures describe fertility under the specified scenarios; they are not predictions of what France’s fertility rate will become.
For women born in 2000, cumulative fertility through the calendar year in which they reached 40 fell from 1.484 in the reference scenario to 1.423 under benchmark postponement with full recuperation, or 1.403 with incomplete recuperation.
However, fertility accumulated by 40 is not completed lifetime fertility. Births occurring after that age would not contribute to this measure, even if they happened subsequently.
The analysis distinguished births deferred beyond 2040 from births assumed never to occur, avoiding the interpretation that every postponed birth was permanently lost.
The researchers emphasised that their model cannot establish why France’s recent fertility decline has occurred or quantify a biological effect of delay. It also did not estimate the impact of expanding assisted reproductive treatment.
Nevertheless, the findings support realistic, non-coercive communication about reproductive ageing alongside measures addressing the social conditions shaping parenthood. Counselling should support individuals’ reproductive goals while respecting decisions about whether to have children.
Reference
Vallée A et al. Fertility in France to 2040 under additional childbearing postponement: a cohort aligned scenario analysis. Reprod Health. 2026. doi:10.1186/s12978-026-02475-x.
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