Introduction: Traditional atherosclerotic cardiovascular disease (ASCVD) risk factors are established, however less is known about a woman’s cardiovascular response to pregnancy, which appears to predict future maternal ASCVD. Spontaneous preterm delivery (sPTD) is associated with a three-fold increased risk of future maternal ASCVD. We investigated the association between sPTD and markers of maternal ASCVD risk.
Hypothesis: We hypothesize that compared to women with term delivery, women with sPTD will demonstrate greater vascular dysfunction postpartum.
Methods: In a case controlled, matched study, we enrolled 20 women with sPTD (gestation ≤34 weeks) and 20 control women (gestation ≥39 weeks) matched for age (±5 years), parity, ethnicity and route of delivery. We collected vascular function measured by augmentation index (AIx75) and central pulse pressure (CPP), a measure of smooth muscle tone; and pulse wave velocity (PWV), a measure of arterial stiffness, within 24-72 hours postpartum. Mixed effects linear regression models were used to analyze the data.
Results: The mean age at enrollment for sPTD and controls was 33 ± 6 years and 32 ± 6 years respectively. Women with sPTD had significantly lower AIx75 (24.10 ± 16.10% vs 39.90 ± 15.2%, p=0.001), and CPP (29.1±5 mmHg vs. 34.6 ±6 mmHg, p=0.004), respectively, compared to controls. Furthermore, women with sPTD and chorioamnionitis (n=8) had significantly lower AIx75 than matched controls (13.5 ±13.7% vs 39.9 ± 15.2% vs, p=0.001) respectively, while women with sPTD without chorioamnionitis had a trend toward lower AIx75 than matched controls (26.6± 15.9% vs. 39.9 ± 15.2%, p=0.065). There was no difference between sPTD and controls in PWV (5.12 ± 1.62 m/s vs 5.58 ± 1.51m/s, p=0.1219), respectively.
Conclusions: Women with sPTD have significantly lower smooth muscle tone measured by AIx75 and CPP, but not lower arterial stiffness, measured by PWV compared to matched controls. These results suggest physiological differences between the two groups possibly due to compounding of vasodilatory effects in smooth muscle tone from localized chorioamnionitis and early gestational age. Further research is required to delineate mechanistic differences in sPTD and its association to future maternal ASCVD risk.