Those in relationships with a partner who is uninterested in sex have heard many excuses, from headaches to stress and more. Now a new study suggests that climate change may be impacting some people’s sex drives, with more hot days to blame.

The study by Tulane University researchers, published earlier this week by the nonprofit National Bureau of Economic Research, suggests that the declining birth rate in the United States may be due, in part, to climate change. The study notes that the increasing number of hot days means people are less interested in sex, with resulting declines in births, according to CNN.

The study reviewed weather data from between 1931 and 2010, looking at periods nine months following days when temperatures reached 80 degrees or higher. They determined that the impact of each of those days resulted in 1,165 fewer babies born, or about 100,000 fewer births each year.

They also note that with climate change, the number of very hot days is expected to increase from 30 per year to about 90 a year.

Previous research has also found impacts on fertility from hot spells, but the new study also looked at whether fertility rebounds following heat waves. The research found a slight uptick, but not enough to make up for the heat-induced decline.

The study’s author noted that heat-related effects, such as impacts on food prices or family income could also impact birth rates, would not be expected to have a direct or immediate effect on birth rates. Thus, the impact of heat, not other factors, is the most likely cause of the drop in birth rates.

Birth rates may also be declining due to non-heat related issues, including greater access to birth control, women entering the workforce, economic downturns and other issues.