The world's population growth is decreasing and recent studies are showing one reason why. According to statistics gathered by several research centers, young adults from around the world are focusing more on their careers, spend more time flirting and prefer living alone instead of getting married and having children.

As the age of marriage and having children increases, the population of the world, especially in developed countries, is being dealt a strong blow.

According to data from the Centers for Disease Control and Prevention in the U.S., the average age of women when they marry has increased from 22.5 to 27.3 in the last 40 years. The same applies to men. In the 1980s, men preferred to marry at the average age of 22, while in 2017, the age of marriage for men increased to 29.5.

Data from the United Nations also shows that the age where people are choosing to have children in Japan increased from 27 to 30 in the last 40 years.

Commenting on the phenomenon, economist Michael Herrmann of the United Nations Population Fund said people want to be economically free and secure before tying the knot. "Young adults want to feel safe financially and finish their academic careers and nowadays, it takes more time than it used to," he explained.