This study evaluates the impact of fertility costs and utility on the third birth intentions among working women with two children in Hainan, China. A cross-sectional survey was conducted in Hainan Island, China in 2021 using an offline survey. Among 1067 working women with two children, only 8.06 % of participants reported having a third-birth intention. After adjustment for potential confounding factors, higher economic cost (odds ratio = 1.89) and lower succession utility (odds ratio = 5.08) were significantly associated with the lack of intention to have a third child. The analysis further demonstrates that family values significantly modulate these economic and utility considerations, highlighting a strong cultural influence on fertility decisions. This finding underscores the necessity for policies that not only mitigate financial burdens but also promote family values supportive of higher fertility. Such measures are essential for creating a cultural and economic environment conducive to higher birth rates.