Association of preterm birth and congenital anomalies: findings of a Brazilian multicenter study

Objective:  to analyze the prevalence of congenital anomalies among women who had preterm births, their association with gestational age, characteristics of pregnancy termination and perinatal outcomes.

Methods:  A secondary analysis of the Brazilian Multicenter Study on Preterm Birth (EMIP), a multicenter cross-sectional study in 20 maternity hospitals, comparing cases of preterm birth with and without anomalies. A random sample of term births served as controls. The risk of malformations was estimated by maternal age, gestational age, type of onset of labour, mode of delivery, and neonatal outcomes using OR (95%CI) for categorical variables.

Results:  Among 4,150 preterm births and 1,146 selected term controls, congenital anomalies were found in 7.21% of cases (8.36% in preterm vs. 3.1% in term). Preterm birth increased the risk of anomalies by 2.89-fold (95% CI: 2.03–4.13). Cardiovascular anomalies were most common (19.1%), followed by central nervous system anomalies (18.8%) and abdominal wall defects (12.5%). The highest risk was observed at 28–31 weeks (OR 4.57, 95%CI 3.01–6.94). Elective cesarean delivery was more frequent among neonates with abnormalities (40.1% vs. 32.1%, OR 1.41, 95% CI: 1.13–1.77). Neonates with abnormalities had a higher risk of low 5^th minute Apgar scores (OR 2.68, 95% CI: 2.01–3.56), birth weight <1.5 kg (OR 1.46, 95% CI: 1.14–1.87), and adverse outcomes such as NICU admission, sepsis, and neonatal mortality (OR 6.0, 95% CI: 4.58–7.85).

Conclusion:  Prematurity is associated with congenital anomalies, leading to increased neonatal morbidity, mortality, and admission to NICU.

Keywords
Congenital abnormalities; Premature birth; Term birth; Infant, newborn; Infant mortality; Gestational age; Maternal age