To measure the incidence of microcephaly among infants of diabetic mothers (IDM) and assess its relationship to metabolic control during pregnancy.
Head circumference data for 556 consecutive live-born singleton infants of women with insulin-requiring diabetes antedating pregnancy delivered between 28 and 40 weeks of gestation and the results of 3,242 HbA1 determinations collected during their pregnancies were examined.
There were fewer head circumferences at or below the 3rd percentne and more at or above the 97th percentik than expected. Head circumference was not related to maternal metabolic control as documented by the HbA1 values.
The less-than-expected incidence of microcephaly observed in this patient population probably reflects the well-known tendency of IDM toward macrosomia.