Introduction:
Preterm delivery (<37 weeks) predicts 2 to 3-fold greater risk of cardiovascular disease in mothers. Development of subclinical cardiovascular risk in these women prior to and following pregnancy is not well understood.
Hypothesis:
Women who deliver preterm have an adverse cardiovascular health profile even prior to pregnancy.
Methods:
Linked data from the population-based, longitudinal HUNT study (1984-2008) and the Medical Birth Registry of Norway (1967-2012) yielded clinical measurements and pregnancy outcomes for 23,179 parous women. Women had up to 3 measurements of body mass index, waist circumference, blood pressure, non-fasting lipids and glucose, and high-sensitivity C-reactive protein (hs-CRP) during a follow-up period between 20 years before first birth to 41 years after first birth. We used mixed effects linear spline models, adjusting for age, pre-pregnancy smoking, education, and time since last meal, to compare risk factor trajectories for women with preterm versus term/postterm first births.
Results:
Women with a preterm first birth (n=1,402, 6%) had significantly higher triglyceride (Figure 1 A) and glucose levels prior to pregnancy. They also experienced steeper increases in systolic and diastolic blood pressure, non-HDL cholesterol, triglycerides, and hs-CRP from first birth to age 50 compared to women who delivered at term/post-term (Figure 1 A,B). Measures of adiposity were similar throughout the life course.
Conclusions:
These results are consistent with the hypothesis that preterm birth is an early marker of cardiometabolic impairment. A history of preterm birth may predict high cardiovascular risk well before the development of traditional risk factors.
Normotensive preterm delivery and maternal cardiovascular risk factor trajectories across the life course: The HUNT Study, Norway
