Glycosylated hemoglobins in normal pregnancy and gestational diabetes mellitus.

Glycosylated hemoglobins (HbA1) were measured in 23 nonpregnant women, 53 normal pregnant women, and 22 Class A diabetics; the results were 6.1 +/- 0.7%, 5.8 +/- 1.0%, and 7.0 +/- 1.3% in the 3 groups, respectively. The decrease in normal pregnancy was insignificant, whereas the increase in HbA1 in Class A diabetics over the other 2 groups was statistically significant (P less than 0.05). HbA1 did not correlate with maternal age, gravidity, or gestational age at the time of sampling. There was no difference in HbA1 between whites and blacks [patients with sickle hemoglobin (HbS) were excluded] (P = 0.35), nor between primigravidas and multigravidas (P = 0.8). HbA1 levels did not correlate with the birth weight ratios in either normal pregnancies (r = 0.06, P = 0.7) or in Class A diabetics (r = -0.4, P = 0.09). This is probably due to the long interval between HbA1 determination and delivery (9.9 weeks).