Cardiac structure and function in moderate-to-late preterm newborns
E A Morell Gjerloeff, M Hoejgaard Andersen, A Eltvedt, S Dannesbo, G Ninh, A S Sillesen, N Vejlstrup, H A Boyd, K Iversen, H Bundgaard, A Axelsson, R Ottilia B. VoeggAbstract
Background
Preterm birth is associated with increased cardiovascular morbidity across the life course. Most preterm births occur in the moderate-to-late preterm period (32+0–36+6 weeks’ gestation). While cardiac alterations have been described in very and extremely preterm infants, the cardiac phenotype of moderate-to-late preterm newborns remains insufficiently characterised.
Purpose
To examine whether moderate-to-late preterm newborns exhibit echocardiographic changes compared with term newborns (≥37+0 weeks’ gestation).
Methods
We drew the study cohort from a prospective, population-based cohort of >25,000 newborns who underwent transthoracic echocardiography (TTE) postnatally, and we investigated left- and right-sided cardiac structure and function. We used multiple linear regression to estimate adjusted mean differences in TTE parameters between moderate-to-late preterm and term newborns. Models were adjusted for infant sex, weight, length, and postnatal age at examination, as well as maternal age, parity, multiple gestation, and pre-pregnancy body mass index. Non-normally distributed variables were natural log-transformed.
Results
The study cohort included 1,199 moderate-to-late preterm and 24,297 term newborns (52% male in both groups). Median age at TTE was 11 days (interquartile range [IQR] 6-19) for moderate-to-late preterm newborns and 11 days (IQR 7-14) for term newborns. Compared with term newborns, moderate-to-late preterm newborns had smaller left ventricular (LV) internal diameters in systole and diastole, reduced end-diastolic interventricular septal thicknesses, and increased left atrial-to-aortic root ratios. LV posterior wall thicknesses, right ventricular dimensions, and the diameters of the aortic arch and inferior vena cava did not differ significantly between groups. Additionally, moderate-to-late preterm newborns had lower heart rates, reduced tricuspid annular plane systolic excursion, and higher peak flow velocities through the aortic valve and LV outflow tract. All differences were minimal. No significant differences were observed in peak pulmonary trunk flow velocities, LV end-diastolic or end-systolic volumes, or stroke volumes.
Conclusion
Moderate-to-late preterm newborns exhibited only subtle structural and functional cardiac differences compared with term newborns, consistent with a largely normal cardiac phenotype in early postnatal life. Longitudinal follow-up is needed to determine the long-term clinical relevance of these findings.