Bad obstetric history (BOH) refers to the occurrence of repeated adverse pregnancy outcomes, including two or more spontaneous abortions, intrauterine foetal deaths, preterm births, stillbirths, congenital anomalies, or early neonatal deaths. It remains a critical reproductive health issue due to its profound emotional, medical and social impact on affected women and their families. Although BOH has multiple causes, its underlying molecular mechanisms are not yet fully understood (1). The present study is therefore relevant, as it focuses on oxidative stress and apoptosis, which are key factors in placental dysfunction, and may aid in the identification of early biomarkers and potential targets for the better prediction and management of BOH.

Oxidative stress occurs when the generation of reactive oxygen species (ROS) exceeds the capacity of antioxidant defence systems. During pregnancy, balanced and physiological levels of ROS are essential for normal placental functions, including trophoblast proliferation, differentiation, invasion and angiogenesis (2). Elevated levels of malondialdehyde (MDA), a widely recognised marker of oxidative stress in maternal blood, reflect increased lipid peroxidation and cellular damage, and have been consistently associated with BOH (3). Excessive oxidative stress can damage cellular components, such as lipids, proteins and DNA, ultimately disrupting normal cell function. At the materno-foetal interface, this oxidative injury can trigger apoptotic pathways, leading to increased trophoblast cell death, impaired placental development and a higher risk of recurrent pregnancy loss (4,5).

Apoptosis is a tightly regulated physiological process that is essential for maintaining tissue balance, particularly at the materno-foetal interface, where controlled trophoblast turnover supports normal placental development. However, when this process becomes dysregulated, it can contribute to pregnancy complications, such as implantation failure and recurrent pregnancy loss. Excessive oxidative stress is a major trigger for apoptosis, as elevated levels of ROS can damage cellular lipids, proteins and DNA, disrupt mitochondrial integrity, and activate intrinsic apoptotic pathways. At the placental level, this oxidative injury promotes trophoblast cell death, the increased shedding of syncytiotrophoblast fragments and heightened inflammatory responses, ultimately impairing placental function and increasing the risk of adverse pregnancy outcomes (6).

Caspase-3, the executioner of the cascade, is recruited during the terminal steps of both the intrinsic and extrinsic apoptotic pathways (7). Previous research has demonstrated that caspase-3 expression is increased in placental tissues from women with BOH, suggesting a role in the abnormal turnover of trophoblasts and trophectodermal dysfunction (8). Caspase-3 is not only a surrogate marker of apoptosis, but also a key functional component in understanding the development of BOH. As further knowledge about its role in pregnancy loss is acquired, it may be possible to identify women at risk earlier and this knowledge may aid in the development of potential biomarkers for its detection.

The p53 gene, known as the ‘guardian of the genome’, is crucial for regulating cell cycle arrest, DNA repair and apoptosis under stressful conditions. During pregnancy, high levels of oxidative stress can lead to trophoblastic apoptosis and affect placental function, which may result in negative outcomes, such as BOH. p53 functions as a molecular connector by responding to oxidative stress and activating pro-apoptotic pathways, such as caspase-3 and BAX, influencing both implantation and foetal survival (9,10). Changes in p53 expression have been noted in women with recurrent pregnancy loss, suggesting that it may serve as a potential biomarker for identifying the condition (11).

Oxidative stress and apoptosis are key biological processes involved in normal pregnancy, and their imbalance has been implicated in the pathogenesis of BOH. Increased oxidative stress can damage placental cells and trigger excessive apoptosis, leading to adverse pregnancy outcomes. The p53 gene plays a central role in linking oxidative stress to apoptosis by regulating cell cycle arrest and programmed cell death. Although p53 is essential for normal pregnancy, its dysregulated expression may contribute to pathological apoptosis in patients with BOH. Therefore, the present study aimed to evaluate the oxidative stress markers, apoptotic markers, and p53 gene expression in women with BOH and explore their interrelationships.

MDA levels (nmol/ml), a marker of oxidative stress, were significantly higher in the cases than in the controls (Fig. 1). The cases exhibited both a higher median value and greater variability, indicating increased oxidative stress in this group. By contrast, the control group exhibited lower and more consistent values, although there were some outliers.

The box plot depicted in Fig. 2 demonstrates the comparison between the caspase-3 levels between the cases and controls. The case group exhibited a higher median and greater variability, with one extreme outlier on the upper end, suggesting increased apoptotic activity in the cells. By contrast, the controls exhibited generally lower values and a more compact distribution, although a few mild outliers were present.

The analysis of p53 expression patterns (Fig. 3) demonstrated a clear difference between the cases and controls. A normal expression was predominantly observed in the controls (78%) compared with the cases (22%). By contrast, upregulation was more frequent in the cases (58%) than in the controls (15%), while downregulation was observed in a smaller proportion in both groups. This indicates that the dysregulation of the p53 gene, particularly its upregulation, is closely associated with the case group, suggesting its key role in disease development.

The mean levels of MDA and caspase-3 were significantly elevated in the cases compared with the controls, suggesting increased oxidative stress and apoptotic activity in the affected group (Table I). Likewise, p53 gene expression, assessed using the 2^-ΔΔCq method, exhibited a significant increase in the cases. All these variances were statistically significant (P<0.01; Table I).

A significant positive correlation was found between MDA levels (nmol/ml), an indicator of oxidative stress, and p53 gene expression (2^-ΔΔCq method). As illustrated in Fig. 4, the correlation coefficient was r=0.4584 (P<0.01), indicating a moderate positive correlation. This suggests that elevated oxidative stress is linked to the increased expression of p53. The regression line also illustrated the trend of rising p53 expression with increasing MDA concentration.

The scatter plot presented in Fig. 5 demonstrated a strong positive correlation (r=0.7136, P<0.01) between p53 gene expression and caspase-3 levels. As p53 is a key regulator of apoptosis and caspase-3 is an executioner caspase, this correlation indicates that the upregulation of p53 directly enhances caspase-3-mediated apoptotic activity.

The present study demonstrates that oxidative stress-induced, p53-mediated apoptosis plays a crucial role in the pathogenesis of BOH. The significantly elevated serum MDA levels observed in women with BOH indicate increase lipid peroxidation and excessive ROS generation, reflecting a sustained oxidative burden. Such an altered intrauterine redox environment is known to disrupt placental homeostasis and initiate cellular stress responses that are essential for maintaining normal pregnancy. Consistent with previous studies linking oxidative stress to recurrent pregnancy loss and placental dysfunction, the findings of the present study suggest that oxidative injury functions as an early and key pathogenic event in BOH rather than merely a secondary consequence (13,14).

Excessive oxidative stress can damage cellular lipids, proteins and DNA, thereby triggering intrinsic apoptotic pathways. In the present study, significantly higher caspase-3 levels in the BOH cases indicate the active execution of apoptosis, confirming that trophoblastic cell death is a prominent feature in these patients (15). Increased apoptotic activity at the materno-foetal interface can impair trophoblast invasion, placental vascular remodelling and nutrient exchange, ultimately compromising placental function and contributing directly to pregnancy failure (16). Thus, oxidative stress-induced apoptosis appears to be a central mechanism linking cellular injury to adverse pregnancy outcomes in BOH.

A key finding of the present study was the marked upregulation in p53 gene expression in women with BOH. The expression pattern analysis revealed that upregulation was significantly more frequent in the cases than the controls, highlighting the role of p53 dysregulation in the development of disease. Notably, the positive correlation observed between MDA levels and p53 expression indicates that increased oxidative stress is closely associated with activation of the p53 pathway (17). This supports the well-established role of p53 as a stress-responsive regulator that becomes activated in response to oxidative DNA damage.

Furthermore, the strong positive correlation between p53 expression and caspase-3 levels provides clear evidence that p53 activation directly promotes apoptotic execution in BOH. Since p53 functions as a transcriptional regulator of pro-apoptotic genes, its overexpression likely shifts the balance from cellular survival toward programmed cell death (18). The coordinated alterations in oxidative stress, p53 signalling and caspase-3-mediated apoptosis indicate a potential molecular axis associated with trophoblastic injury and placental dysfunction. These markers may serve as a biomarker panel for early risk stratification and clinical monitoring in BOH, enabling targeted surveillance and supportive management. However, these applications remain preliminary and require validation through prospective and interventional studies. Notably, p53 expression, in conjunction with related markers, may aid in early risk detection, although causality cannot be inferred from this case-control study.

The present study had certain limitations, which should be mentioned. The case-control design may be prone to selection bias, as participants were recruited from a single geographic region in South Kerala, India. The single-centre setting and lack of multivariate adjustment for potential confounders, such as lifestyle variables and associated clinical conditions may also affect the generalisability and interpretation of the findings. The cross-sectional nature of the study limits the ability to establish causality, making it unclear whether p53 upregulation is a cause or a consequence of oxidative stress in BOH. The present study also relied on biomarker measurements without functional or mechanistic experiments, which limits direct confirmation of the causal role of the oxidative stress-p53-apoptosis pathway. Larger, multicentre longitudinal studies with experimental validation are thus required to strengthen these findings.

In conclusion, the findings of the present study support an association between oxidative stress, p53-mediated apoptosis, and BOH. Elevated levels of oxidative stress are associated with an increased expression of p53, which is associated with enhanced trophoblastic apoptosis, potentially contributing to impaired placental function. The coordinated upregulation of oxidative stress markers, apoptotic indicators, and p53 expression suggests a possible molecular link underlying BOH. Collectively, these results indicate that p53 may function as a potential mediator linking oxidative stress and apoptosis in BOH. The assessment of p53 expression, along with oxidative stress and apoptosis markers, may provide insight for early risk identification and clinical monitoring in susceptible women.