Excessive birth weight and maternal glucose tolerance--a 19-year review.

The incidence of birth-weight of 4,540 g (10 lb) or more rose from 0.87% in the years 1971 to 1977 to 1.16% in the 12 years from 1978 to 1989 with a concomitant increase in hyperglycaemia in our antenatal population. The relationship between excessive birth-weight and maternal glucose tolerance was investigated in the light of these observations. The results from glucose tolerance tests performed routinely during the pregnancies of 510 women who delivered infants with a birth-weight of 4,540 g or more were compared with those from a control series of 5,003 women with consecutively tested pregnancies. Glucose tolerance in subsequent pregnancies was also compared with the control series, and in 1991 the study group women were investigated for emergence of permanent diabetes mellitus. Excessive birth-weight was associated with maternal hyperglycaemia (p < 0.05) but not with gestational diabetes; 79% of infants with birth-weight > or = 4,540 g were born to mothers who were not hyperglycaemic. There was no increase in glucose intolerance in subsequent pregnancies in the study group and only 2 of 49 women with follow-up testing had diabetes mellitus. Birth-weight > or = 4,540 g occurred in 1.1% of the total population and 1.1% of women with gestational diabetes, and was related to maternal hyperglycaemia in about 1 in 5 cases. The increased incidence of excessive birth-weight infants was not related to the increased incidence of gestational diabetes in our pregnant population. Birth-weight > or = 4,540 g had a poor association with later development of diabetes.