Most animals in nature follow an instinctual mating habit that reflects the season. Do we humans follow a similar pattern? Over the years, I have noticed that there is a natural ebb and flow regarding due dates. There are often many due dates around the same time, with a particular upraise of birth during the summer. Last week in class we had more then half of the mother’s due within 4 weeks! For summer babies to arrive, that means the babies were conceived in the fall and early winter. I rationalized this occurrence as the fall being a time to start up again; the carefree feeling of summer is over, school begins and people return to a more normal routine of life. Interesting, according to this birth date ranking chart from NPR, the months of July, August and September indeed have the highest number of births.
While my reasoning behind this conception period is more of a social mindset (one last summer of fun!), there has actually been scientific correlations to this conception period as well. According to the study, Annual Rhythm of Human Reproduction: II. Environmental Correlations out of the University of Munich “Conception rates are above the annual mean at temperatures between 5° and 20°C” (48-68 degrees Fahrenheit)(2) An article from the New York Times also supports this of the perfect time to conceive.
“According to the new analysis, the perfect time of year to conceive is when the sun shines for about 12 hours and the temperature hovers between 50 and 70 degrees Fahrenheit. For reasons that remain mysterious, such conditions somehow help stimulate either ovulation in women, a burst of sperm production in men or a combination of the two.
In some regions of the world, the scientists say, people mating in the optimal fertility season have twice the chance of conceiving that they might have the rest of the year.” (3)
As nature reminds the birds to fly south for the winter and the wood creatures to mate in the fall, it also provides us human mammals with an ideal conception periods. Perhaps we are not that different from the other creatures of nature.
*Side Note- Referring back to the birth chart above, notice that most national holidays have low birth rates. I believe this could be an indication of the manipulation of birth days. Inductions and c-sections are probably not scheduled on these days….interesting!