Tissue destruction leads to hearing loss, brain defects, cataracts and pulmonary artery stenosis. In utero infection with herpes has become an uncommon even in the past few years. Congenital herpes infection may be prevented by cesarean section in mothers with active lesions. The risk of malformation is 3-4 times that of a normal pregnancy. Disturbed carbohydrate metabolism has been associated with an increased risk of stillbirth, neonatal deaths and abnormally large infants.
Diabetes controlled by insulin severely reduces the risk of congenital malformation.
Therapy should begin well before conception to ensure a normal fetus. The mechanism of these malformations has not been fully elucidated, but it has been shown that it is the alteration in glucose levels and not the insulin which is teratogenic. A neurulating or gastrulating mammalian embryo is critically dependant upon maternal glucose levels. Even brief periods of decreased glucose concentrations are teratogenic. J.L. Sever and R.L. Brent.