Did you know that not all birthdays are created equal? In France, some days see many more babies born than others, while some dates remain surprisingly rare. Far from being the result of chance, this unequal distribution of births says a lot about our lifestyles, the organization of the health system, but also the evolution of family behavior. Find out when births are rarest.
A birth rate far from uniform throughout the year
According to INSEE, around 663,000 babies will be born in France in 2024. But these births are not evenly distributed over the twelve months of the year. Historically, France has long experienced a strong seasonality of births. Between the mid-19th century and the beginning of the 20th, babies were mostly born… between February and April. Religious practices, such as Lent or Advent, then slowed down conceptions at certain periods, which concentrated births at the beginning of the year. This is no longer the case.
Today, these determinants have disappeared, but seasonality remains in another form. Since the 1990s, you may have noticed, “baby season” has shifted from spring to summer and early fall. In short, in the summer. This is only a reflection of new social and professional rhythms.
The rarest months and days to be born
Contrary to popular belief, it is not the summer months that record the fewest births. INSEE figures for the period 2015-2024 show that these are mainly the winter months, and in particular December, January and Februarywhich have the fewest births today. Winter babies are therefore rare.
Certain dates stand out very clearly:
- December 25, the rarest day of the year, with around 1,600 births on average, or 22% less than the daily average;
- January 1 (-11%);
- December 31 (-7%);
- February 29, naturally rarer, even in leap years.
These targeted lows are largely explained by the organization of maternity wards. Public holidays and weekends see fewer scheduled births. However, 7% of births take place by planned cesarean section and 26% following induction. Result: Sunday records around 13% fewer births, and Saturday 9% fewer than a weekday.
Holidays, heat and rhythms of life: new determining factors
But the design cycle also plays a key role. Certain periods of the year are less conducive to the start of pregnancy, notably the month of August, marked by holidays, fatigue or extreme heat, or the month of May, often broken up by public holidays.
Heat waves also have a measurable impact. Nine months after a heatwave, births generally decrease. The heatwave of August 2003, for example, led to a 6% drop in births in May 2004. However, INSEE observes that this effect has diminished over the past fifteen years, suggesting an adaptation of behavior and living conditions.
July and September, birth champions!
Conversely, certain months concentrate a high excess birth rate. From July to October, births are 2% to 5% more numerous than the daily average. July 20 even holds the national record, with around 2,210 births, or 9% more than an ordinary day.
These peaks very clearly correspond to conceptions that occurred during the All Saints’ and Christmas holidays. The end of year celebrations are associated with more free time, less contraceptive vigilance and a climate conducive to family plans. The month of September also benefits from a “back to school” effect, much sought after by some parents for practical or academic reasons.
Finally, as demographer Nathalie Blanpain points out, parents are increasingly seeking to choose the period of birth, favoring the summer months, perceived as more pleasant and compatible with vacations.
A birth rate revealing changes in society
Beyond the figures, the distribution of births reflects the profound changes in French society: rise in planned births, decline in the influence of marriage on conceptions, transformation of work rhythms… Although the birth rate has been generally declining for several years, it continues to draw, month after month, a very telling map of our contemporary lifestyles.