Depression is the most common psychiatric illness, characterized by persistent feelings of sadness, loss of interest or pleasure in activities, as well as cognitive and physical symptoms (Smith, 2014). In the United States, depression affects 5–10 % of the population, with higher rates of up to 40–50 % in specific primary care or specialist settings (Wang et al., 2017). Depression is not only a mental health disorder but also an independent risk factor for various diseases such as coronary heart disease, hypertension, and diabetes. It affects people of all ages, genders and backgrounds and is a leading cause of disability and suicide (GBD 2019 Adolescent Mortality Collaborators, 2021; Hedegaard et al., 2020). Unfortunately, only about half of those with depression receive adequate treatment due to limited effective interventions and insufficient mental health resources (González et al., 2010). To develop effective prevention strategies and interventions, it is crucial to understand the risk factors associated with depression due to the harm it causes to individuals and society.

Reproductive lifespan, a key concept in the field of women's health, refers to the duration of time which a woman is biologically capable of reproduction, from the age at menarche to age at menopause (Nabhan et al., 2022). It encompasses the various milestones and physiological changes that occur throughout a woman's reproductive years, including menstrual cycles, fertility and hormonal fluctuations (Te Velde and Pearson, 2002). In recent years, advancements in healthcare access, nutrition, and environmental conditions have contributed to an extended female reproductive lifespan (Nichols et al., 2006). Notably, in the United States, the average reproductive lifespan has increased by 2.1 years over the past six decades (Appiah et al., 2021). Understanding reproductive lifespan expectancy is crucial as it provides insights into the reproductive health and potential challenges faced by women during different stages of their lives. In recent years, there has been growing interest in exploring the relationship between reproductive factors and depression. McGuire et al. conducted a study revealing that girls with a more advanced pubertal status, earlier pubertal timing, and heightened concerns about social rejection exhibited a higher likelihood of experiencing worsening depressive symptoms (McGuire et al., 2019). Wisner et al. found a consistently high prevalence of depressive symptoms during pregnancy and postpartum, with up to 20 % of pregnant women reporting suicidal thoughts (Wisner et al., 2013). Furthermore, Vivian-Taylor et al. concluded that the menopausal transition was associated with an increased incidence of depressive symptoms (Vivian-Taylor and Hickey, 2014). While these individual reproductive factors have been studied to some extent, there is a research gap regarding the broader concept of reproductive lifespan and its association with depression.

Therefore, the primary objective of this study is to investigate the relationship between reproductive lifespan and the incidence of depression, while considering the age at menarche and age at menopause, in a large sample of female participants from the United States.