Ludvigsson JF, et al. - In this population-based cohort study involving 2474 singletons born to women with type 1 diabetes (T1D) and 1,165,216 reference infants born to women without diabetes, researchers analyzed preterm birth risk in women with T1D based on periconceptional levels of hemoglobin A_1c [HbA_1c]. In 552 of 2474 infants born to mothers with T1D compared to 54 287 in 1,165,216 infants born to mothers without diabetes, preterm birth occurred. Findings revealed that the risk for preterm birth has been strongly associated with periconceptional levels of HbA_1c. There was also an increased risk for women with HbA_1c levels consistent with recommended target levels.