Have you ever wondered why they ask for birth certificates issued no later than 3 months before the current date? It's because anything that affects your civil status - marriage, divorce, death, etc. is recorded directly on your birth certificate in France. Now, that is not true if you come from Australia, for example, which means that there is absolutely no valid reason for providing a recent certificate. I had my birth certificate translated by a "traducteur assermenté" when I needed it the first time in France. I made sure I got several copies "assermentées". Now I just keep using the same one, explaining each time that there are no "annotations" in Australia. They hum and ha but once they've checked it out, everything is fine. I have been married twice, divorced once and aquired French nationality, all using that one certificate. It certainly saves a lot of money.
Now, there's something else I'd like to tell you that many people don't know. You may have children who were born here but need a translation of their birth certificate into French (or another language) for some reason. All you have to do is ask the mairie to give you an international birth extract (same principle as the international drivers' licence) and it doesn't cost a red cent!