Hot, sticky humidity is enough to make people think twice about hitting the sheets. According to a recent study conducted by the National Bureau of Economic Research, there is now a correlation between the hottest days of the year and a decline in birth rates.
Researchers based their findings on statistics from 1931-2010, drawing a connection between days that were warmer than 80 degrees and the number of births nine months later. They found that there were 0.4% fewer births nine months after sweltering days, resulting in a total of nearly 1,200 fewer babies born nationwide. There was an increase in the amount of births between 11 and 13 months following the hottest days, but that slight uptick didn’t make up for the kids who weren’t born during the heat wave.
So as the globe heats up, the theory goes, we’ll see more and more days above that 80-degree threshold—meaning fewer days you’re likely to heat things up in the comfort of your bedroom.
Higher temperatures can also harm the reproductive health of both men and women by hindering sperm function and testosterone levels as well as negatively effecting the menstrual cycle.
However, there are more factors to consider than just hot days. “People might be constrained to conceiving in certain calendar months because they have time off work,” said Alan Barreca, lead author of the study and associate professor of economics at Tulane University. In the past several decades, men and women have also been presented more birth control options; more women are populating the workforce; and financial factors may discourage couples from having children altogether.
