Preterm birth and future maternal blood pressure, inflammation, and intimal-medial thickness: the CARDIA study

Abstract

Preterm birth (PTB, <37 weeks) may be a marker of endothelial dysfunction and a proinflammatory phenotype; both are risk factors for cardiovascular disease. We studied 916 women (46% black) with 1181 live births between enrollment in the Coronary Artery Risk Development in Young Adults study (age 18-30 years) and 20 years later. C-reactive protein was measured at years 7, 15, and 20. Interleukin-6 and carotid intima-media thickness, which incorporated the common carotid arteries, bifurcations, and internal carotid arteries, were measured at year 20. Blood pressure, lipids, anthropometrics, and pregnancy events were assessed at all visits. Change in risk factors and differences in inflammatory markers and intima-media thickness according to PTB were evaluated. Women with PTBs (n=226) had higher mean systolic blood pressures before pregnancy (106 versus 105 mm Hg, respectively; P=0.03). Systolic and diastolic blood pressure increased more rapidly over 20 years compared with women with term births (P<0.01 time interaction), even after removing women with self-reported hypertension in pregnancy. Women with PTB versus term births had similar mean intima-media thickness adjusted for age, body mass index, race, lifestyle, and cardiovascular risk factors. C-reactive protein and interleukin-6 did not differ according to PTB. Women with PTB, regardless of hypertension during pregnancy, had higher blood pressure after pregnancy compared with women with term births. In the United States, where rates of PTB are high and race disparities persist, PTB may identify women with higher blood pressure in the years after pregnancy.

Figure 1

Maternal systolic blood pressure (Panel A), diastolic blood pressure (Panel B), and BMI (Panel C) from baseline to year 20, according to preterm birth history (n=916). Asterisks indicate cross sectional differences according to preterm status with p<0.05 using Wilcoxon test.

Figure 2

Maternal systolic blood pressure (Panel A), diastolic blood pressure (Panel B), and BMI (Panel C) from baseline to year 20, according to preterm birth history in women with no pregnancies complicated by hypertension (n=680). Asterisks indicate cross sectional differences according to preterm status with p<0.05 using Wilcoxon test.