Aim: Congenital malformations and macrosomia in infants of women with type 1 diabetes mellitus (DM1) still occur, even if diabetic control is considered 'good' (i.e. HbA1c below the nonpregnant upper reference value of 6.3%). We, therefore, measured HbA1c in healthy, pregnant women to determine whether the upper reference value for pregnant women should be lower than the nonpregnant value.
Methods: We investigated HbA1c, measured by high-performance liquid chromatography (HPLC), in two groups of healthy primigravid women. Group 1 (n=30; 30.0 +/- 5.3 (mean +/- sd) years; body mass index (BMI) before pregnancy 21.7 +/- 5.3 kg/m2) had a gestational age of 30 weeks (34.6 +/- 2.5) pregnant. None of the women had diabetes in the family in the first and/or second degree.
Results: Group 1 had an HbA1c of 4.3 +/- 0.3% (range 3.9-5.0) and in group 2 the HbA1c was 4.7 +/- 0.4% (range 3.6-5.9) (p < 0.001). No relation was found between HbA1C and BMI vs birth weight, corrected for gestational age, within the groups.
Conclusions: Healthy, pregnant women had a low HbA1C, particularly in the first trimester of pregnancy. This might implicate that for prevention of congenital malformations and macrosomia in pregnant DM1 women and HbA1C should be below 5% in the first trimester of pregnancy and below 6% in the third trimester.