**Background:** Prior research has established that parental absence during childhood can negatively affect children's current health and development, but few studies have examined how the timing of parental absence across different developmental stages affects long-term physical and mental health outcomes in adulthood. This study aimed to fill that gap by analyzing the effects of living without parents at four distinct age stages (0–6, 7–12, 13–15, and 16–18 years) on adult health outcomes, with additional analysis of gender differences.
**Methods:** Data were drawn from the 2018 China Labor-Force Dynamics Survey, a nationally representative survey using multistage cluster and stratified probability-proportional-to-size sampling across 29 provincial administrative units. After excluding missing values and outliers, the analytic sample comprised 3,464 respondents aged 18–36 years (mean 28.225, SD 5.206). Physical health was measured by a single self-rated item on a 5-point Likert scale (1 = very unhealthy to 5 = very healthy). Mental health was assessed using the Center for Epidemiological Studies Depression (CES-D) scale (range 20–80, Cronbach's alpha 0.949). The explanatory variable was whether respondents lived with both parents during each of four age ranges: 0–6, 7–12, 13–15, and 16–18 years. Ordered probit regression was used for physical health outcomes, and ordinary least-squares regression for mental health outcomes. Propensity score matching (PSM) with four matching methods (nearest-neighbor with caliper, radius, kernel, and local-linear regression) was employed to address self-selection bias. Control variables included gender, age, years of schooling, marital status, log income, smoking, drinking, exercise, and province fixed effects.
**Key Results:** Among the sample, 9.6% lived without parents at ages 0–6, 10.4% at ages 7–12, 14.0% at ages 13–15, and 21.9% at ages 16–18. The mean physical health score was 3.995 (SD 0.820) and mean CES-D score was 26.858 (SD 8.217). In benchmark regressions, living without parents at ages 0–6 was associated with significantly worse physical health (coefficient = −0.223, p < 0.01) and worse mental health (coefficient = 2.632, p < 0.01) in adulthood. Significant negative effects on physical health were also found for ages 7–12 (coefficient = −0.169, p < 0.01) and 13–15 (coefficient = −0.099, p < 0.1), but not for ages 16–18. For mental health, significant negative effects were found across all age ranges: ages 7–12 (coefficient = 2.178, p < 0.01), 13–15 (coefficient = 1.355, p < 0.01), and 16–18 (coefficient = 0.696, p < 0.05). Gender-stratified analyses revealed that for physical health, parental absence at ages 0–6 was significant for both males (coefficient = −0.161, p < 0.1) and females (coefficient = −0.285, p < 0.01), but at ages 7–12 it was significant only for females (coefficient = −0.217, p < 0.01). For mental health, parental absence was significant for males only before age 15, while for females it was significant across all age ranges (0–18). The magnitude of negative effects was consistently larger for females than males at every age stage. PSM results confirmed the robustness of these findings, with all ATT estimates remaining statistically significant across all matching methods.
**Clinical Implications:** These findings demonstrate that parental absence during childhood has lasting, stage-dependent effects on adult physical and mental health, with the strongest impacts from early childhood (0–6 years) absence. The results suggest that clinical screening for adverse childhood experiences should include assessment of parental absence timing, and that interventions to mitigate long-term health consequences should be prioritized for children separated from parents at younger ages. The pronounced gender differences—with females showing vulnerability across all age stages—indicate that girls may require additional support and monitoring when parental absence occurs. For China specifically, where 6.436 million rural children were classified as left-behind as of 2020, these findings underscore the need for policy interventions to minimize parent-child separation and provide early intervention services for affected children.