In the 14th Five-Year Plan period (2021-25), the government aims to bolster the fertility rates by helping families alleviate the costs of giving birth, raising children and school and university education, and more supportive policies are expected to be rolled out, according to the plan.

"In the short term, the third-child policy is foreseen intensifying desire for childbearing, driving the structural growth of the consumption market. In the long term, the relaxation of the family planning policy is expected to alleviate the pressure emerging from an aging society in China," said Li Jincan, an analyst at the LeadLeo Research Institute, a market research provider.

In 2016, China relaxed its 35-year-old single-child policy in favor of a second-child policy. That encouraged Chinese couples to give birth to more than 10 million second children, according to China's latest national census.

Still, increasingly, Chinese women are getting married later and delaying their motherhood, fueled by constant economic growth and a change of lifestyle.

The average age of Chinese women getting married for the first time increased from the age of 21.4 in 1990 to 25.7 in 2017, and the average age of Chinese women getting pregnant for the first time increased from 23.4 in 1990 to 26.8 in 2017. The figures seen in major Chinese cities are close to some developed countries such as Japan, according to the National Bureau of Statistics.

"Low fertility rate is a result of economic and social development. The fertility rate is affected by policy factors, and it is also affected by economic, social and cultural factors. The influence of the latter factors is gradually increasing in China," said Ning Jizhe, head of the NBS, at a news conference in May.

"With continuous social development and economic growth, people's notion of childbearing has changed, especially as a result of industrialization and modernization. Low fertility rate has become an issue that is widely faced by most developed countries, and it's going to become a practical problem in China," Ning said.

Meanwhile, the number of women who are in a suitable age to give birth is declining. According to UN data based on the number of fertile women aged between 15 and 44, the population of women in this age group in China started to decline in 2008.

When women give birth at an age of 35 or older, they would be defined as expectant mothers in an older age, according to medical definition in China. For those who have the willingness to have three children, it is highly likely that they would have turned 35 or older at the time of giving birth to the third child.

With advancing age, the rate of women getting pregnant and safely giving birth decreases. Thus, demand for follicle-stimulating hormonal treatment and other assisted reproductive services is expected to increase gradually, said Li of LeadLeo.