Introduction
Aging-related diseases and premature death pose significant threats to health[1-4]. Given the global impact of these issues, it is crucial to comprehend the influence of modifiable risk factors. Women childbirth is a fundamental aspect of human behavior, playing a vital role in maintaining women’s health. Current studies on childbirth and women’s health predominantly focus on the health effects of the number of births, leading to two contrasting viewpoints. Some studies propose that childbirth may reduce the risk of breast cancer, uterine cancer and ovarian cancer by decreasing exposure to progesterone and estrogen[5,6], which is believed to counteract negative physiological changes that accumulate with an increasing number of births, potentially delaying the aging process[7]. Conversely, other studies argue that childbirth consumes a significant portion of resources through reproduction, diverting resources away from the maintenance and repair of somatic tissues, consequently accelerating the aging process. Therefore, it remains largely uncertain whether and how the number of childbirths influences women’s health.
Further, results from observational studies regarding the potential link between number of births and women’s risk of mortality are inconsistent[8-12]. Some studies found that there is a negative association between number of birth and women’s risk of mortality, whereas other studies showed that such association is U-shape[13,14]. There are even studies suggesting a non-significant association[15]. Despite the relatively large sample sizes in some studies, they often failed to account for potential confounding factors such as economic, behavioral, and dietary variables[13,14,16]. At the sociological level, raising children can avoid unhealthy behaviors by improving their lifestyle and often involves more social participation[17,18], but it may also increase women’s stress, related depression risks, and significant economic costs[19-23]. Therefore, there is a need for a comprehensive study with a sufficiently large sample size that considers a wide range of confounding variables.
To fill this knowledge gap, this study utilize data from the UK Biobank (UKB) to assess the association between the number of live births and women’s aging, premature all-cause mortality, and life expectancy. Meanwhile, extensive confounding including socioeconomic factors, lifestyle factors and biological factors were adjusted for accurate evaluation. This study may add insights into relationships between childbirth and women’s aging, premature all-cause mortality, and life expectancy for the first time, for clinical and public health reference, being useful for future production interventions.