People are more interested in sex around Christmas — and there’s a baby boom nine months later

People really do have more sex around Christmas — and there’s a baby boom nine months later to match, according to new research that looks at Google searches and Twitter posts.

Researchers looked at web searches about sex from 2004 to 2010 and 10 percent of public Twitter posts from 2010 to 2014. (The results were published this week in the journal Scientific Reports .) The data came from 130 countries and both hemispheres, which is crucial to show that the increase in birth rates is because of cultural factors related to a holiday, and not simply biological factors related to more or less daylight being available.

By analyzing the data, the scientists confirmed that interest in sex does peak during major cultural celebrations and they correlate with an increase in births nine months later. The spike was consistent for Christmas in countries that were majority Christian, and about the end of Ramadan for countries that are majority Muslim. (Thanksgiving and Easter, however, did not create the same spikes in interest.)

Though the seasons are reversed, the trend held, and so the researchers think that it’s a cultural trend, and not one that’s triggered by biological shifts or changes in daylight. The results — in addition to helping us all mock September babies — could help public health researchers figure out the best dates to launch safe-sex campaigns in developing countries.