Spontaneous Preterm Birth as a Sentinel for Cardiovascular Mortality: Insights from a National Registry Study

Highlights

• Women with a history of spontaneous preterm birth (sPTB) exhibit a 38% increased risk of cardiovascular mortality (CVM) compared to those with term births.
• The risk for CVM is gestation-dependent, peaking at a three-fold increase (aHR 3.19) for women with early spontaneous preterm birth occurring before 32 weeks.
• While the risk is lower than that associated with hypertensive disorders of pregnancy (HDP) or fetal growth restriction (FGR), sPTB remains an independent and significant predictor of long-term cardiovascular health.
• Postpartum cardiovascular screening and risk stratification are increasingly recommended for all women with a history of preterm delivery, regardless of the subtype.

Background

Preterm birth (PTB), defined as delivery before 37 weeks of gestation, affects approximately 10% of pregnancies worldwide and is a leading cause of neonatal morbidity. While extensive research has established the link between medically indicated preterm birth (often driven by hypertensive disorders of pregnancy or fetal growth restriction) and future maternal cardiovascular disease (CVD), the long-term implications of spontaneous preterm birth (sPTB) have remained less clear. Spontaneous PTB has traditionally been viewed as an inflammatory or infectious process, distinct from the vascular-mediated pathologies of preeclampsia. However, emerging evidence suggests that sPTB may share common etiological pathways with cardiovascular dysfunction, potentially serving as an early “stress test” that reveals underlying vascular or metabolic vulnerabilities.

Key Content

The Dutch Registry Cohort Study: Methodology and Primary Outcomes

In a landmark population-based cohort study conducted in the Netherlands, Welters et al. (2026) utilized data-linkage between the National Hospital Birth Registry and the National Death Registry to track over 1.16 million women who had their first birth between 1995 and 2015. With a median follow-up of 11.3 years, the study is one of the largest to specifically isolate sPTB—defined as PTB without the presence of HDP or FGR—from other forms of preterm delivery.

The results were striking. Among the 109,935 women who experienced any type of PTB, the adjusted Hazard Ratio (aHR) for cardiovascular mortality was 1.94 (95% CI 1.61–2.33). When focusing specifically on the 74,722 women with sPTB, the CVM risk remained significantly elevated at 1.38 (95% CI 1.02–1.87). Most notably, the risk intensified as gestational age decreased: women with early sPTB (22–32 weeks) faced an aHR of 3.19 (95% CI 1.84–5.56) compared to those who delivered at term.

Integrating Global Evidence and Comorbid Risk Factors

The findings from the Dutch cohort align with broader global trends. Data from the Global Burden of Disease (GBD) 2023 analysis on East Asia indicates that maternal hypertensive disorders—which often lead to indicated PTB—are declining in mortality rate but still contribute significantly to the maternal health burden (PMID: 42159072). The Dutch study complements this by suggesting that even in the absence of overt HDP, the process leading to spontaneous early delivery may involve vascular mechanisms similar to those seen in preeclampsia.

Further supporting the vascular-immune link, recent research into gestational diabetes mellitus (GDM) has demonstrated that immune cells such as placental CD4+ T cells can drive hypertensive phenotypes and renal injury in animal models (PMID: 42070109). This suggests that the inflammatory milieu associated with sPTB might overlap with the immune-mediated vascular damage characteristic of other pregnancy complications. Additionally, the role of the gut microbiome in modulating maternal immune responses—essential for fetal tolerance—has been identified as a factor in PTB and preeclampsia, providing a potential metabolic-inflammatory link to long-term health (PMID: 42026776).

Methodological Advances in Risk Stratification

To improve early identification of women at risk, clinicians are exploring non-invasive markers of vascular and fluid status. Prospective studies using bioelectrical impedance analysis (BIA) have shown that extracellular water (ECW) expansion is not only a hallmark of preeclampsia but also correlates with adverse perinatal outcomes (PMID: 42057556). While primarily used in high-risk HDP patients, such tools may eventually find utility in assessing the underlying vascular health of women following sPTB, particularly those delivering at very early gestational ages.

Expert Commentary

The Dutch study underscores a critical shift in how we interpret spontaneous preterm birth. For decades, obstetricians focused on the infectious/inflammatory markers of sPTB. We now recognize that a significant proportion of these births—particularly early sPTB—may represent a “vascular-mediated” subgroup. The three-fold increase in CVM risk for women delivering before 32 weeks is clinically profound and suggests that the mechanisms triggering early spontaneous labor may be fundamentally linked to maternal endothelial health.

However, several controversies remain. One limitation of registry-based studies is the inability to control for all lifestyle factors, such as smoking, BMI, or socioeconomic status, which might independently influence both PTB risk and CVM. Moreover, while the association is clear, the exact causal pathway remains hypothesized. Is sPTB a cause of future CV damage, or is it merely a marker of a pre-existing, latent cardiovascular predisposition? Given the long-term projections that PTB will remain a sustained public health burden through 2050 (PMID: 42101201), the implementation of systematic postpartum cardiovascular follow-up is no longer just an option—it is a necessity.

Conclusion

Spontaneous preterm birth, particularly when it occurs prior to 32 weeks, is a significant and independent predictor of subsequent cardiovascular mortality. While the absolute risk is lower than that seen in deliveries complicated by HDP or FGR, the sheer volume of sPTB cases globally makes this a major public health concern. Future clinical practice must evolve to include these women in long-term cardiovascular screening programs. Research should now focus on identifying the specific “vascular-mediated” biomarkers within the sPTB population to enable targeted interventions during the critical “fourth trimester” and beyond.

References

• Welters SM, De Groot CJM, Kamphuis EI, et al. Spontaneous Preterm Birth and Subsequent Cardiovascular Mortality: Linked Registry Cohort Study. BJOG. 2026;133(7):1100-1110. PMID: 42225294.
• Liu X, et al. Maternal hypertensive disorders in East Asia, 1990-2023: incidence, deaths, DALYs and maternal mortality. Hypertens Pregnancy. 2026. PMID: 42159072.
• Gomez-Lopera NM, et al. Placental CD4+ T cells from women with gestational diabetes recapitulate disease features in a pregnant rat model. Hypertens Pregnancy. 2026. PMID: 42070109.
• Zhang Y, et al. Bioelectrical impedance-derived extracellular fluid expansion and perinatal outcomes in preeclampsia. Hypertens Pregnancy. 2026. PMID: 42057556.
• Chen H, et al. Gut microbiome and pregnancy complications: emerging evidence and mechanistic insights. Gut Microbes. 2026. PMID: 42026776.
• Amirkhanova A, et al. Forecasting preterm birth in Kazakhstan through 2050: a cohort-component demographic modeling study. Glob Health Action. 2026. PMID: 42101201.