You might be interested in threads from the FAQ section on "France's Population Growth in the Industrial Era":
What are the factors behind of the slow population growth of France in the 19th Century? (5 comments | 2 years old) - Economic, social, sexual, and security factors
Why has France had a slow increase in population compared to other Western European countries, especially during the Industrial Revolution? (3 comments | 1 year old) - Malthusian limits, legal issues, lack of lifespan changes, industrialization
What was the cause of France's low population growth compared to Germany or England? (6 comments | over 1 old) - Industrialization comparisons
Why did France stagnate in terms of population growth from the early 19th century until after WWII, while other countries around it grew very rapidly? (7 comments | over 2 years old) - Napoleonic Wars & Napoleonic Code