Congenital malformations among infants whose mothers had gestational diabetes or preexisting diabetes

Background: Diabetes type 1 is associated with an increased risk for infant congenital malformations. It is debated whether this is true also at gesta tional diabetes. Aims: To study occurrence of congenital malformations in i nfants whose mothers had preexisting or gestational diabetes. Study design: A register study covering over 1.2 million Swedish births in 1987-1997 bas ed on the Swedish health registries. Subjects: We identified from the Medic al Birth Registry 3864 infants born of women with preexisting diabetes and 8688 infants born of women with gestational diabetes. Outcome measures: Con genital malformations identified in the Medical Birth Registry. the Registr y of Congenital Malformations, and the Hospital Discharge Registry. The rat es of congenital malformations among these infants was compared with the po pulation rates. Results: At preexisting diabetes, the total malformation ra te was 9.5% while the rate at gestational diabetes was similar to the popul ation rate, 5.7%. At preexisting diabetes, certain conditions were more com mon than expected: orofacial clefts, cardiovascular defects, oesophageal/in testinal atresia, hypospadias, limb reduction defects, spine malformations, and polydactyly. For some of these conditions, an excess was found also fo r infants whose mothers had gestational diabetes. Infants with multiple mal formations were in excess at preexisting diabetes but nut at gestational di abetes but the specific type of malformations involved were similar in the two diabetes groups. Conclusions: It is suggested that in the group of gest ational diabetes exists a subgroup with an increased risk for a diabetes em bryopathy, perhaps due to preexisting but undetected diabetes type 2. (C) 2 001 Elsevier Science Ireland Ltd. All rights reserved.