The birth rate in the U.S has largely been on decline for the past century, and there are numerous reasons attributed to this drop, including birth control access as well as increased professional opportunities for women, not to mention the cost and headache of having children. A new study published by the National Bureau of Economic Research suggests that climate change may be another factor in the declining birth rate. To determine this, researchers investigated the birth records 9 months after really hot days (anything over 80 degrees, which incidentally and ironically is known as a cooler summer day in many places). They found that about 1,165 fewer babies were born each day, nine months after these scorchers, resulting in about 100,000 fewer births across the country per year. Although the study did show that some procreating couples may simply have postponed their baby making until the weather became cooler (indicated by an increase in births about 11-13 months after the hot days), those “rebound” births only made up for about 32% of the decline after nine months. Climate change may also have another, more physiological effect on reproductive possibilities: studies have linked impaired sperm function and reduced testosterone with high heat exposure. Considering that hot days are only expected to increase in both frequency and intensity as a result of climate change, it will be interesting to see how these trends continue and/or worsen.