Every year on September 16, millions of people around the world celebrate their birthdays, making it the day with the largest number of birthdays in the world. This also shows that winter is the peak period for pregnancy. According to the American emerging media "Daily Fun News Network", there are many interesting patterns in human sex, which are as accurate as a calendar.

December is the peak pregnancy period every year, and August is the "low" period for pregnancy throughout the year. Research from the University of Texas believes that "from a biological point of view, the reason is that sperm quality is not high in summer, and long days and short nights can affect ovarian function; while December has many holidays and cold weather, and people tend to have more intense sex, making it easier to get pregnant."

The most people have sex on Fridays, and Monday is the time when sexual activity is low. The data comes from Tokyo Fun's 2011 sex survey. The survey covered the time period, location, frequency of sexual life of men and women in Tokyo, as well as the identity of their sexual partners. It was found that 56% of people would have sex on Friday, followed by Saturday at 30%, followed by Thursday, Wednesday, Sunday, Tuesday and Monday.

83% of people like to make love on rainy or cloudy days. A large-scale survey conducted by a condom company in the United States shows that people are more likely to have a desire for intimacy on rainy days, and their feelings for each other will become closer.

Some people refuse to be intimate because the weather is hot, and some people don't want to be intimate because of the cold. The former is twice as likely as the latter. A survey in the United States found that 35% of people have repeatedly refused to be intimate because of the hot weather, while 19% of people have refused to be intimate because of the cold weather.

The odds of making out in the evening are 13 times higher than in the afternoon. The people surveyed said that sexual intercourse requires the right time and place. Although sexual desire is high in the afternoon, it is not suitable for sex. After finishing the day's work, it is more suitable for sex in the evening.

The frequency of sex will increase after the job becomes stable. Researchers at the University of Lugano in Switzerland found that job instability can lead to low sexual desire, and that sex will be more harmonious for a period of time after the job enters a stable period.