Infants of diabetic mothers have been shown in several studies to have an increased frequency of malformations. In previous studies, an increased frequency of several specific malformations has been noted, including anencephaly, bilateral renal agenesis, and double outlet right ventricle. Surveillance, used to identify all malformed infants in a consecutive sample of births, can identify a distinctive pattern of malformations among the affected infants.(1) Maternal pregestational diabetes mellitus is associated with an increased risk for congenital malformations of about2-4 times the background risk.(2) Perinatal outcome of the infant of the diabetic mother (IDM) depends on the onset, duration, and severity of maternal diabetes and is worse for IDM born from mothers with pre-existent insulin-dependent diabetes.(3) that glycemic control is associated with a reduced risk of congenital anomalies. However, the recommended threshold of HgA1c for pregestational diabetic women planning pregnancy is still not known.(4) Congenital anomalies are broadly classified into either single-system or multiple-system malformations. The first type affects a single organ system or body part,(5,6,7) and the second affects more than one organ system or body part. Major congenital anomalies are defined as those that, if uncorrected, could result in considerable impairment of the normal body functions or even reducing the life expectancy. Minor congenital anomalies include the anomalies that cause no disability or have no significant physical or functional effects and can be regarded as normal variants.(5,8,9) In another study conducted in Egypt on live-born babies, the incidence of minor congenital anomalies among infants of diabetic mothers was 18%, while the incidence was 11% for the major congenital anomalies, the later was 4.6 times higher than in the general population.(10) The pathophysiology of maternal diabetes induced birth defects is complex, however, clearly relates to maternal glucose levels. The mechanism is not entirely understood, but animal studies have shown it to be associated with decreased cell proliferation and increased cell apoptosis due to high oxidative stress, the second major change is altered gene expression causing deviation from the normal developmental process.(11) However, most congenital defects associated with diabetes occur in the cardiovascular, central nervous and musculoskeletal systems. Although hyperglycemia is a common mechanism for teratogenicity, differences in disease characteristics, such as age of onset, ethnicity, obesity and duration of disease, may affect the disease impact on the perinatal outcome and the rate of congenital anomalies.(11,12)
The purpose of this study was to determine the pattern of congenital anomalies associated with maternal diabetes mellitus in newborns attending Assiut University children's Hospital.