- Preterm birth risk was strongly linked to periconceptional HbA1c levels among women with type 1 diabetes (T1D), and excess risk was seen even within the recommended range.
Why this matters
- The relationship between maternal glycemic control and preterm birth has been unclear.
- Swedish population-based cohort study of 2474 singleton infants born to women with T1D and 1,165,216 infants born to 746,916 women without T1D.
- Funding: Swedish Diabetes Foundation.
- Preterm birth (
- Preterm birth incidence:
- HbA1c 6.5%-7.7%: 20.6%.
- HbA1c 7.8%-9.1%: 28.3%.
- HbA1c >9.1%: 37.5%.
- Adjusted risk ratios (aRRs; 95% CIs) for preterm birth in T1D vs non-T1D, by HbA1c:
- 6.5%-7.7%: 4.22 (3.74-4.75);
- 7.8%-9.1%: 5.56 (4.84-6.38); and
- >9.1%: 6.91 (5.85-8.17).
- With HbA1c cutoff lowered to
- Higher HbA1c levels were associated with secondary outcomes of large for gestational age, hypoglycemia, respiratory distress, Apgar score
- Possible residual confounding.
- HbA1c values not available for all patients with T1D.
- No data on physical activity, drinking habits, or race/ethnicity.
- BMI based on self-reported height.
- All-Swedish population.