Impact of moderate-to-late preterm birth on diastolic function in newborns
M Hoejgaard Andersen, E A Morell Gjerloeff, A Eltvedt, H A Boyd, G Ninh, R Ottilia B. Voegg, A S Sillesen, N Vejlstrup, H Bundgaard, K Iversen, A Axelsson Raja, S DannesboAbstract
Background
Globally, preterm birth affects more than one in ten live births and is associated with increased risks of hypertension, ischaemic heart disease, heart failure, and metabolic disease later in life; yet the underlying mechanisms remain unclear. Previous studies are based on small cohorts and report contradictory findings on diastolic function in newborns, leaving it uncertain whether alterations are measurable at birth.
Objective
To assess whether moderate-to-late preterm newborns (32-36 completed weeks’ gestation) exhibit echocardiographic changes in left ventricular diastolic function compared with term newborns (≥37+0 weeks’ gestation).
Methods
The study cohort included newborns from a prospective, population-based cohort study in paediatric cardiology, all of whom underwent systematic transthoracic echocardiography (TTE) postnatally. Left ventricular diastolic function was assessed using transmitral peak flow velocities during early diastole (MV E Vel) and atrial contraction (MV A Vel), deceleration time, and left atrial end-systolic volume (LAESV). LAESV was calculated in the apical four-chamber view using Simpson’s biplane method. The E/A-ratio was calculated as the ratio of early (E) to late atrial (A) transmitral inflow velocity. We used linear regression to estimate differences in mean parameter values between moderate-to-late preterm and term newborns. Models were adjusted for infant sex, weight, length, and age at examination, maternal age at delivery, pre-pregnancy body mass index, and multiple gestation. TTE variables were log- or square-root-transformed prior to analysis, and adjusted means were obtained as model-based marginal means back-transformed to the original scale (geometric means for log-transformed outcomes).
Results
The cohort included 25,496 newborns, of whom 1,199 were born moderate-to-late preterm. The term and preterm groups both comprised 52% males. Mean gestational age at birth was 35.6 weeks (standard deviation [SD] 1.1) in the preterm group and 40.1 weeks (SD 1.3) in the term group. Preterm infants had smaller LAESV (adjusted mean 1.91 cm3 vs 2.01 cm3; square-root transformed, β = -0.04, 95% confidence interval [CI] -0.06, -0.02, p<0.001). MV E Vel and MV A Vel did not differ statistically between the two groups. Similarly, no significant difference was observed in MV deceleration time. The MV E/A-ratio was slightly lower among preterm newborns (adjusted geometric mean 1.03 vs 1.05; conditional adjusted mean percent difference -2.13%, 95% CI -3.93, -0.30, p = 0.02).
Conclusion
In this large population-based cohort, moderate-to-late preterm newborns demonstrated left ventricular diastolic function comparable to that of term newborns, with no indication of impairment.