T2∗ weighted placental MRI in type 1 diabetes pregnancies – a prospective study based on the FaPDi cohort

INTRODUCTION: Pregnancies complicated by type 1 diabetes are at increased risk of obstetric complications related to an impaired placental function. Using T2∗ weighted placental MRI, this study aimed to compare placental function between pregnancies with and without type 1 diabetes. METHODS: A prospective cohort study in pregnant women; 25 with type 1 diabetes and 38 without diabetes, at Aalborg University Hospital. Placental transversal relaxation time (T2∗) was measured at three study visits in gestational weeks (mean ± SD) 17.0 ± 1.1 (Visit 1), 28.5 ± 0.7 (Visit 2), and 35.3 ± 1.1 (Visit 3). Placental T2∗ was compared at each visit and correlated with birth weight deviation. RESULTS: In type 1 diabetes placental T2∗ was significantly increased (10.8 ± 4.7 ms, p = 0.02) at visit 1 and significantly reduced at visit 2 and 3 (-15.9 ± 5.5 ms, p < 0.01) and (-13.9 ± 5.2 ms, p = 0.01), respectively. Placental T2∗ z-score showed a positive correlation with birth weight deviation in both groups, but at any given birth weight deviation T2∗ z-score was significantly reduced in type 1 diabetes when compared to non-diabetes (1.9 ± 0.4, p < 0.01). CONCLUSION: In pregnancies complicated by type 1 diabetes, birth weight is increased and placental T2∗ is reduced in the third trimester when compared to pregnancies without diabetes. The combination of increased fetal metabolic demand and reduced placental function is challenging. Direct assessment of placental function is highly needed, as low birth weight is not a reliable indicator of placental dysfunction in these high-risk pregnancies.