Selective Screening Strategies for Gestational Diabetes: A Prospective Cohort Observational Study

Figure 1

Nomograms (a) with HbA1c and (b) without HbA1c. The nomograms consider the history of delivery of a previous baby > 4000 g (prevmacrosomia: 0 = no, 1 = yes), random glucose (gluc: measurement in mmol/l), and BMI (BMI: mass in kilograms/height in metre²). Two nomograms are illustrated to show the difference with and without and HbA1c measurement being included. The score is derived by aligning the points on each number line with the “points” line at the top. The total score is then calculated and plotted on the “total points” line. When this total score is compared to the prob(GDM) line, the probability of developing GDM is derived. For example, a 30-year-old woman who is now para 2 gravida 3, with a BMI of 35 kg/m2, who previously delivered a 4.3 kg baby, has an HbA1c of 5.8% and now has a random glucose of 6.7 mmol/l will have a score of 155 and thus a 50% chance of developing GDM in this pregnancy based on the nomogram without the HbA1c. Her score is 182 and thus a 52% risk of developing GDM if the HbA1c is incorporated into the prediction model. Prevmacrosomia: history of delivering a baby > 4000 g; gluc: random glucose; BMI: body mass index; HbA1c: glycated hemoglobin; Prob(GDM): probability of developing gestational diabetes.

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(b)