Cardiovascular Malformations Among Preterm Infants

Abstract

Objective. Preterm birth and cardiovascular malformations are the 2 most common causes of neonatal and infant death, but there are no published population-based reports on the relationship between them. We undertook this study to determine the prevalence and spectrum of cardiovascular malformations in a preterm population, the prevalence of prematurity among infants with cardiovascular malformations, and the influence of prematurity and cardiovascular malformations on outcomes. Methods. We based the study on the population of the former Northern Health Region of England. We identified all live-born infants with cardiovascular malformations diagnosed in the first 1 year of life from the regional pediatric cardiology database, which includes the gestational age and details of the diagnosis. We limited ascertainment to malformations diagnosed by the age of 12 months. Infants with isolated patent ductus arteriosus or atrial septal defect were excluded, to avoid ascertainment bias. Infants with ventricular septal defect were classified according to whether they required surgery in the first 1 year. There are no population data on gestational ages for all births in our population for the era of this study; therefore, we used data published in the literature for populations similar to our own to predict that 0.4% of live births occur at Results. Of 521619 live-born infants in 1987–2001, 2964 had cardiovascular malformations (prevalence: 5.7 cases per 1000 live births). Cardiovascular malformations were present at 5.1 cases per 1000 term infants and 12.5 cases per 1000 preterm infants. The odds ratio (OR) for a cardiovascular malformation in prematurity was 2.4 (95% confidence interval [CI]: 2.2–2.7). We found that 474 infants (16%) with cardiovascular malformations were born at Conclusions. This study showed that preterm infants have more than twice as many cardiovascular malformations as do infants born at term and that 16% of all infants with cardiovascular malformations are preterm. It also showed, not surprisingly, that there is an increased mortality rate among infants born preterm with a cardiovascular malformation. The additional effect of cardiovascular malformations on mortality rates is most marked for term and near-term infants, for whom mortality rates are otherwise low. The excess of cardiovascular malformations among preterm infants is intriguing but not easy to explain. Previous studies of birth weight among infants with cardiovascular malformations reported a significant increase in the likelihood of being small for gestational age among infants with tetralogy of Fallot, complete atrioventricular septal defect, hypoplastic left heart, or large ventricular septal defect. There is an obvious relationship between birth weight and gestational age, and those studies also showed an increased prevalence of prematurity among infants with tetralogy of Fallot, pulmonary stenosis, aortic stenosis, coarctation of the aorta, complete atrioventricular septal defect, or ventricular septal defect. There is also a high prevalence of cardiovascular malformations among late stillbirths, with major differences in the number and spectrum of cardiovascular malformations, compared with those seen in postnatal life. In particular, there is a greater incidence of coarctation of the aorta, double-inlet left ventricle, hypoplastic left heart, truncus arteriosus, double-outlet right ventricle, and atrioventricular septal defect among stillbirths. This spectrum of malformations is similar to that in our study and to those in other reports. Whether the increased prevalence of cardiovascular malformations among preterm infants and the increase in stillbirths suggest clues to the cause is difficult to say. The influence of preterm birth should be taken into account in risk assessment and risk stratification for surgical repair.