Ideal birth spacing between the first and second child among reproductive-aged women in Shandong Province, China.

Objectives: This study aims to assess the ideal birth spacing between the first and second child among reproductive-aged women in Shandong Province and to examine its influencing factors using the Social Ecological Model. It was hypothesized that women's ideal birth spacing is influenced by factors at the individual, family, and sociocultural levels, with these factors exerting different effects across categories of ideal birth spacing. Methods: A multistage random sampling method was employed to obtain a sample of 2,090 women. Descriptive statistics, univariate analysis and a generalized ordered logit model (gologit) were employed to identify factors associated with ideal birth spacing. Average marginal effects (AMEs) were calculated to interpret the magnitude of significant associations. Results: Among 2,090 participants, 46.32% preferred medium ideal birth spacing (3-4 years), 21.10% preferred short (0-2 years) and 32.58% preferred long spacing (≥5 years or no specific preference). Univariate analysis revealed that age, education level, marital status and fertility-related factors were significantly associated with ideal birth spacing ( Conclusion: Women's ideal birth spacing is shaped by multiple factors across individual, family, and sociocultural levels, with their effects differing across short, medium, and long spacing preferences. Policies aimed at reducing childcare burdens, improving policy awareness, and providing stage-specific support may help women better achieve their preferred reproductive timing.