Message to French men and women aged 29: your biological clocks do not forgive, and from your age, fertility rates decrease, so it would be advisable for you to consider the option of preserving your eggs and sperm for future use, so you never have to say, "If only I had known...". A letter with a more or less similar content will be sent from June to thousands of young French people about to turn thirty, as part of the "demographic rearmament" announced by President Emmanuel Macron and included among the 16 measures of the French Ministry of Health's plan...