The relationship of differential marital status with health has been a subject of discussion for a long time [1,2,3,4]. Numerous approaches and methods have been used to evaluate the association between marital status and health, eventually developing two major schools of opinion.
One school of researchers argues that marital status affects individuals’ health status [5,6,7]. Farr , one of the pioneers in studying marital status and health debate, stated that marriage is a positive factor in lowering mortality among individuals than mortality among the unmarried, starting the hypothesis of marriage protection. The term “marriage protection effects” refers to the positive benefits of marriage on mortality and morbidity [6, 9, 10]. Marriage, it is assumed, strengthens social support, and wealth and prevents risky behaviour, leading to improved health. As a result, several studies have also reported that married people have lower mortality rates [11, 12], longer life expectancy [13, 14], fewer physical health problems [15, 16], are protected from life stresses and depression [17, 18], and shorter hospital stays, lower chance of nursing home admission as well as better quality health care use [19,20,21].
By contrast, other schools argue that individuals’ prerequisite health level explains the lower mortality and better health outcomes of married individuals than in other unmarried categories [22,23,24]. As per this second hypothesis, the “marriage selection theory,” healthier individuals are more likely to marry, or their marital union is less likely to change. Additionally, empirical data reveals that marriage markets exhibit positive assortative mating, which is the occurrence of mating between like people at a frequency greater than random . Most of these findings are from developed countries like Sweden, the USA, Serbia, and other developed countries focusing on the complex association between marital status and health [3, 23, 24, 26,27,28,29]. Despite the long-standing links between marital status and health, studies from developing countries have mostly avoided diving further into the intricacy of the linkages between marital status and health by studying the broad marital hypothesis. It is crucial to note that the gender element was shown to attenuate the differences in marital status and health status.
Concentrating on the gender issue, a substantial body of evidence demonstrates that marriage provides women with the same health benefits as it does men; the evidence comes mostly from gender-equal countries such as North America and Europe. However, the findings on whether health influences marriage or whether marriage influences health by gender are ambiguous. For instance, Hanson et al.  found significant association between marriage and health only for men and men are more likely to suffer poor health status due to unmarried status. At the same time, some of the evidence suggests that marriage is more beneficial for women .
SRH is worth mentioning in this context since it is an important and extensively used health indicator that has been shown to be an effective indicator of objective health measures and lifestyle-related health status [32,33,34,35,36]. Evidence have suggested that self-reported health can predict the mortality risk, Obesity, hypertension, and metabolism [32, 35]. Simultaneously, the relationship between self-reported health (SRH) and marital status has been thoroughly explored. Although, it has been shown that married persons have a better SRH than single, divorced, widowed, or otherwise unmarried individuals, there are also mixed finding on the association between marriage and self-reported health [37,38,39]. For example, Fu & Noguchi  in their study, found that marriage affects people’s objective health by increasing their risk of developing lifestyle disease, while in terms of the selection impact; it is found that better subjective health tends to attract middle-aged and elderly Japanese to marriage. Another study by Hu  reported that the difference in health status between single and married rural women is mainly explained by the marital selection, whereas the difference in health status between married and widowed rural women is explained by marital protection in China.
Unlike many Western countries, marriage is still nearly universal in many south Asian countries . In south Asian countries, marriage remains the cornerstone for long-term relationships, and virtually everyone marries at some point. Unmarried individuals endure enormous societal pressure to marry, which intensifies with age . On the other hand, men and women who are widowed, divorced, or separated face social and economic disgrace . Furthermore, many previous studies have considered the marital status as a crucial social determinant of the health and explored different dimensions of the health in the light of the marriage protection hypothesis in particular [42,43,44,45,46]. However, evidence is absent from the Asian context, and significantly less is known, particular from India.
In India, where male dominance continues to exist, the culture is highly normative, patrilineal, and patriarchal [47,48,49]. Previous research has demonstrated that gender inequalities in marriage and health outcomes strongly persist [18, 20, 50,51,52,53]. At the same time, several studies have focused on self-reported health and marital status in India. For instance, Pandey and Jha , using Structural Equation Modelling (SEM), concluded that poor economic circumstances had a mediation effect on the association between widowhood and poor self-reported health in India. Perkins et al.  found that women widowed for an extended period were more likely to have psychological distress and poor self-rated health. Further, Sudha et al.  suggested that even after controlling socioeconomic and family times, unmarried, particularly widows had poorer self-reported health than married older women. Further, Lloyd-Sherlock et al.  compared SRH status between married and widowed individuals in SAGE countries, i.e., China, Ghana, India, the Russian Federation, and South Africa, suggesting that widowed women had higher poor SRH compared to married women. Although these previous studies have given a more comprehensive range of explanations for the poor self-reported health among unmarried individuals compared to married individuals, limited studies have tried to assess the hypothesis of marriage protection and marriage selection on SRH in India. Further, less is known about how gender and age play a role in these hypotheses.
Thus, given this broader context, this study uses the Study on Global AGEing and Adult Health (SAGE), 2006–07 with followed-up data to 2015 and addresses specific questions: 1. Is there a protective or selective relationship between marriage and health? We consider this subject in the context of SRH. 2. How do gender and age play a role in analysing such a hypothesis? This study contributes to the current body of knowledge in two ways. First, this study utilizes panel data to examine theoretical frameworks of marriage in the Indian setting concurrently, bringing substantial empirical evidence to this research area. The marital protection hypothesis is examined by estimating the influence of marriage on the change in self-reported health. The marital selection hypothesis is examined by estimating health-related selection into stable and unstable marital status. Second, this study will aid in the investigation of age and gender differences in marriage and health link.