Discussion
In present study, we showed that diastolic dysfunction statistically increases as the number of pregnancies increases. Additionally, cut of value of parity for diastolic dysfunction was 6.5 which is higher than other studies [6, 12].
Previous studies showed that cardiovascular mortality increases along with increased parity [7]. Changes in the renin-angiotensin-aldosterone system explain this mechanism [14]. Estrogen secreted by placenta increases the release of angiotensinogen. Angiotensinogen produces angiotensin-2 that activates the RAS system. RAS system induces sodium and water retention. As a result, increased afterload is observed along with pregnancy. Also decreased relaxin levels affect cardiovascular mortality during pregnancy [15]. However, these changes continue only with pregnancy and their effects after pregnancy are still not clear.
We also found that diastolic function deteriorates as the parity increases. Aggarwal et al, performed the first known study on this issue and they found the same results[16]. Other studies similarly showed that diastolic dysfunction increases with the parity [6, 12]. However; they performed these studies up to 7 pregnancies (grand multiparity). In our study, women that have a history of 9 and more pregnancies (great grand multiparity) were also included. The present study has the highest number of parity in the literature.
There is lack of evidence about relationship between the parity and the severity of diastolic dysfunction. Kim et al. found that 2.5 and above parity number significantly increases the diastolic dysfunction[6]. Other study performed by Keskin et al. showed that pregnancies of 4 and above significantly increase the diastolic dysfunction [12]. In our study, the cut-off value for diastolic dysfunction severity according to the ROC curve analysis was 6.5 pregnancies. This difference attributed to the number of pregnancies included in this study is higher than other studies before.
Aortic stiffness is a prognostic risk factor for cardiovascular mortality. In the present study, binary logistic regression analysis showed that presence of hypertension and diabetes mellitus did not make a significant difference in terms of diastolic dysfunction; however number of pregnancies and age did make a significant difference. This can be attributed to increasing of aortic stiffness. In our study, we showed the same results as the previous studies in the literature [17-20].
In the present study, significant decrease in ejection fraction was observed as the number of pregnancies increases. However, this decrease did not reach the systolic dysfunction range (greater than %50). Although Kim et al. found same results as ours; other studies did not show this correlation [6, 12, 16]. This result attributed to be exposed of long time diastolic dysfunction as our study population has higher pregnancy numbers.