To reduce the burden of medical expenses for childbirth, the National Healthcare Security Administration has proposed a reform goal of "striving to achieve a situation where individuals have no out-of-pocket expenses for childbirth within the policy coverage range across the country". The zero out-of-pocket policy can reduce the burden of medical expenses for childbirth, but it will also increase the expenditure of the medical insurance fund. Based on the individual data of childbirth at a hospital from 2023 to 2025, this paper sets up four reform policy scenarios, and simulates and calculates the impact of the zero out-of-pocket policy on the medical insurance fund expenditure from both static and dynamic perspectives. The simulation calculation show that the zero out-of-pocket policy will significantly increase the medical insurance fund expenditure for childbirth reimbursement, but its impact on the overall medical insurance fund expenditure is limited. The zero out-of-pocket policy has a greater impact on the medical insurance fund expenditure for residents' childbirth than for employees' childbirth. From a dynamic perspective, the zero out-of-pocket policy has a greater impact on the medical insurance fund expenditure. By controlling the rate of cesarean sections and the medical expenses for childbirth, the impact of the zero out-of-pocket policy on the medical insurance fund expenditure can be effectively reduced. The research indicates that the zero out-of-pocket policy is generally feasible, but all regions need to strengthen the calculation of medical insurance fund expenditure, gradually promote the zero out-of-pocket policy, and simultaneously strengthen the management of medical expenses for childbirth.