The willingness of families to have children plays a crucial role in long-term population development. Currently, China is experiencing a significant risk of low fertility, with low fertility becoming the prevailing trend.

Under the macro background of the comprehensive liberalization of the ''three-child policy'', this study aims to analyze the willingness of the population to have children and the varying influencing factors across different age groups and establish a foundation for developing pertinent fertility policies by elucidating the concerns about fertility held by various age groups.

The data used in this study was sourced from the 2021 China Comprehensive Social Survey (CGSS). This study selected a population aged 20-44 years old, and after excluding missing variables, a total of 2 525 samples were included, including 1 444 females. A study on the entire population is conducted in order of age from young to old, with one group every 5 years old, for a total of 5 groups; Research on women was divided into two groups based on age groups of 34 and 35 and above. Using multiple variables from three dimensions of personal characteristics, family characteristics, and attitudes as possible influencing factors, an ordered Logistic regression model was used to analyze the factors affecting fertility intention in the entire population and only for women.

The number of people willing to have two children accounted for 59% of the total survey population (1 491/2 525), and the group under 34 years old had a higher willingness to have zero children compared to the group over 35 years old (P<0.05). The results of Logistic regression analysis showed that, among individual characteristic variables, individuals with better health conditions were more likely to have a higher willingness to have children, which was significant in the population aged 35-39 and women over 35 years old (P<0.05). In the family characteristic variables, people with a larger family size were more likely to have a higher willingness to have children, which was significant in the population aged 25 and above and women over 35 years old (P<0.05). There was a higher likelihood of having a stable partner with a higher willingness to conceive, which was significant in women under 34 years old (P<0.05). In the concept attitude variables, all variables of the 20-24 were group were significant, and the results showed diversity in other age groups.

The current mainstream fertility intention is to have two children, and the fertility intention of young people (under 34 years old) is relatively high. Better physical health and larger family size are more prominent in the age group of 35 and above, and attitudes have a stronger impact on fertility intentions, with significant age differences. It is recommended to pay attention to the reproductive views of different age groups, strengthen family, social, and policy support, attach importance to women's physical health, and provide medical support for childbirth.