Background

The uterus and its myometrium undergo several changes during delivery. In labor, the myometrium performs contractions to expel the newborn. In a cesarean section, however, the myometrium is incised. Little is known about labor-induced changes in biomarkers that are known to rise during injuries and exhaustion of another muscle, the heart. These markers can also be produced by the myometrium, especially damaged myometrium. Since labor is known to cause slight myocardial challenge, physiological changes in cardiac biomarkers in the context of labor versus after an incision of the uterus are of new interest. Here, we question whether cardiac biomarkers could also be produced by the uterus. If this were the case, the interpretation of the myocardial ischemic marker peripartum needed a revision. This study investigated whether cardiac biomarkers might be influenced by uterine activity or injuries from cesarean sections.
Methods

We conducted a prospective study on the peripartum trajectories of creatine kinase (CK, cardiac isoenzyme CK-MB), high-sensitivity cardiac troponin-T (hs-cTnt), and N-terminal pro-B-type natriuretic peptide (NT-Pro-BNP) in 44 cardiologically healthy pregnant women. The participants were stratified by delivery mode: cesarean section (CS, n = 24) versus vaginal delivery (VD, n = 20).
Results

Our findings indicate that ischemia biomarkers (hs-cTnT, CK and CK-MB) increase more during the postpartum period than they do after a cesarean section, whereas NT-Pro-BNP levels increase after cesarean section. These elevations remained within normal ranges and were not associated with clinical symptoms.
Conclusion

Biomarker levels differ based on delivery mode, indicating that mode of birth influences biomarker fluctuations postpartum within a physiological range. The incision of the uterus does not reveal higher marker levels than contractions do; therefore, this kind of myometrial damage is not associated with an increase in ischemic biomarkers. The observed elevations are linked to slight myocardial damage in the peripartum phase after labor, comparable to exercise. The myometrium does not appear to provide evidence for a clinically meaningful contribution based on peripheral measurements of highly sensitive troponin, CK and CKMB.