Do infants with major congenital anomalies have an excess of macrosomia?

Background: Infants that develop congenital anomalies may also have an exce ss prevalence of macrosomia (birth weight greater than or equal to4,000 g). This may indicate that abnormalities of glycemic control play a role in th e etiology of birth defects. This study was undertaken to determine whether all infants with congenital anomalies have an excess of macrosomia and whe ther it is confined to specific types of anomalies. Methods: A case-control study was conducted, comparing the birth weights of 8,226 infants with congenital anomalies ascertained by the Texas Birth Def ects Monitoring Division with those of 965,965 infants without birth defect s. Odds ratios were calculated to determine the association between birth w eight and congenital anomalies, for 45 specific defects, and for all these defects combined. Results: For all 45 defects combined, a significant association occurred on ly in the highest birth weight category. Infants with congenital anomalies were more likely than infants without birth defects to have a birth weight greater than or equal to4,500 g (OR = 1.65; 95% CI = 1.39-1.96). Infants bo rn with ventricular septal defects, atrial septal defects, ventricular hype rtrophy, or anomalies of the great vessels were 1.5-2.5 times more likely t o weigh greater than or equal to4,000 g than were infants without birth def ects. Based on small numbers, a stronger excess of macrosomia was observed for infants with encephalocele, holoprosencephaly, anomalies of the corpus callosum, preaxial polydactyly, and omphalocele. Conclusions: Our data suggest that infants with specific congenital anomali es are more likely to be macrosomic than are infants without an anomaly. If these findings are confirmed, associations between macrosomia and specific types of birth defects may help to identify birth defects that are caused by alterations in glycemic control. (C) 2001 Wiley-Liss, Inc.