Background: Spontaneous preterm delivery (sPTD) is associated with a twofold increased risk of future maternal cardiovascular disease. We hypothesized that women with sPTD would demonstrate greater vascular dysfunction postpartum compared to women with term delivery. Materials and Methods: In a case-controlled, matched pilot study, we enrolled 20 women with sPTD (gestation ≤34 weeks), and 20 term control women (gestation ≥39 weeks) were matched for age (±5 years), parity, ethnicity, and route of delivery. Vascular function, serum lipids, C-reactive protein, and interleukin-6 were completed within 24-72 hours postpartum. Statistical analysis included paired t-tests based on match and mixed effects linear regression models and adjusted for potential confounders. Results: The mean age for sPTD and term controls was 33 ± 6 years and 32 ± 6 years, respectively. Women with sPTD had significantly lower augmentation index-75 (24.1% ± 16.1% vs. 39.9% ± 15.2%, p = 0.001) and central pulse pressure (29.1 ± 5.4 mmHg vs. 34.6 ± 4.7 mmHg, p = 0.004), but no difference in pulse wave velocity (5.1 ± 1.6 m/s vs. 5.6 ± 1.5 m/s, p = 0.12) compared to controls. Women with sPTD had significantly lower high-density lipoprotein cholesterol (59.4 ± 12.5 mg/dL vs. 67.6 ± 13.1 mg/dL, p = 0.035) compared to controls. Analysis of chorioamnionitis and magnesium sulfate did not alter the results. Conclusions: Women with sPTD have signs of lower smooth muscle tone in the early postpartum period compared to women with term delivery. Further research is required to understand mechanistic pathways in sPTD and future maternal cardiovascular disease risk
