According to a new survey released by the recruitment website Zhaopin, 67% of working women with one child don't want a second, up from 50% in 2014, The New York Times reports. In addition, the survey found 40% of childless women don't want any kids at all, up from 21% in 2016.

Economists tend to look upon situations like China's with concern. When countries don't have enough kids but also see rising elderly populations, as China does, the economy tends to suffer. People feel the squeeze of social-security costs and limit spending. Less spending means fewer resources to raise kids.

In the most extreme cases, these vicious cycles are known as "demographic time bombs," and they take awhile to form.

"These things happen gradually over the decades," Brendan Burchell, a University of Cambridge sociologist, tells Business Insider. "It's not like you wake up one day and suddenly the world's full of old people dependent on workers having to work harder and harder."

That especially makes sense in a country like China, where the one-child policy lasted more than 35 years, from 1979 to 2015. The economy boomed during that time, mainly as a result of slowed population growth, but now there is an abundance of senior citizens and too few workers to support them.

A couple gets ready for their wedding photo session on a boat that takes tourists from Chinese side of the Yalu River close to the shores of North Korea. Damir Sagolj/Reuters

Their hunches are often correct. Of the women surveyed, 32.5% saw their salaries decline after having kids. That's up from 24.2% of women surveyed in 2016. In addition, 36.1% said they'd been demoted after having kids in 2017, while 26.6% said the same in 2016.

China's government is aware of the demographic time bomb, although it has limited its mission of raising the fertility rate to marketing and advertising. Some local organizations have been using the slogan "Doing it starts with me." Meanwhile, countries like Singapore and Turkey offer cash incentives to families to have more kids.

Generally, experts are skeptical these gimmicks can work in the long run. In Japan, which is widely considered another demographic time bomb, many say the only solution is to make work-life balance easier for women and be more accommodating of families.

If China wants to defuse its own demographic time bomb, it may need to forge a similar path.