Congenital anomalies (CA) are relatively frequent and have been reported to be more frequent in infants born preterm (<37 weeks of gestation) than full term. However, the correlation between degree of prematurity and incidence of CA is unknown.
Aims The first aim of this study is to assess the incidence of CA according to weeks of gestation. The second aim is to evaluate the correlation between the number and the severity of CA and gestational age.
Methods This is a hospital-based study, which utilized neonatal data between 2001 and 2006 from a hospital in Montreal, Canada.
Results Over this time period, 19 105 live births were recorded and the incidence of CA was 7.9%. A regression demonstrates an inverse relationship between CA (without CA vs with one or more CA) and gestational age (β = −0.109; F(1, 19103) = 228.48, p<0.001). An inverse correlation is also found between the number of CA and gestational age (β = −0.136; F(1, 19103) = 359.45, p<0.001). This relation is also present within term births. Indeed, child born at 37 weeks of gestation are more at risk (OR: 2.41; 95% CI: 1.13 to 5.18) to have at least two CA than child born at 41 weeks of gestation. The inverse relation between CA and gestational age is stronger for major (β = −0.133) than minor CA (β = −0.039), but both are significant.
Conclusions Incidence, importance (major vs minor) and co-occurrence of congenital anomalies are inversely correlated with the gestational age including within the term range.