Risk factors for critical and complex congenital heart diseases: Case-control study

Background: Congenital heart defects (CHD) are the most common type of congenital defects. Despite having much better-defined risk factors nowadays, the etiology of most CHDs remains unknown. In only 10 to 15 % of cases, a well-established causal relationship can be defined.Objective: To identify risk factors for critical and/or complex congenital heart disease as well as to estimate the current prevalence of these conditions in newborns.Methods: The present case-control study was matched by maternal age and newborn sex, performed between 2014 and 2016 by active search, involving interviews and the analysis of medical records, as well as clinical evaluation in newborns with critical or complex CHD. Our study was performed in the maternity and neona-tology departments of four major public hospitals in the city of Salvador, Bahia-Brazil.Results: Sixty-one cases of critical and/or complex congenital heart disease were identified, with 122 controls selected at random from 20,917 live births during the study period. The prevalence of critical and/or complex CHD was 292 cases per 100,000 births. The most frequent kinds of complex CHD were coarctation of the aorta and interrupted aortic arch. Our reduced conditional logistic regression model identified the following risk factors: Number of pregnancies (odds ratio [OR]: 8.97 [1.75-46], p = 0.009), and known maternal (OR: 6.62 [1.23-35.81], p = 0.028) or paternal (OR: 8.88 [2.31-35.63] p = 0.002) family history of malformations.Conclusion: We observed a high prevalence of critical and complex CHD in the studied population. The final conditional logistic regression model identified a history of three or more pregnancies and a known paternal family history of malformations as independent risk factors for critical congenital heart disease.