Fetal Growth and Placental Function in Pregnancies Complicated by Diabetes

Plain-language summary

Diabetic pregnancies are often complicated by placental dysfunction with reduced transfer of oxygen from the mother to the fetus, which may compromise fetal growth and organ development. In diabetic pregnancies, hyperinsulinemia and hyperglycemia very often leads to fetal macrosomia. The combination of reduced placental oxygen transfer and increasing fetal demand due to fetal overgrowth may possess a particular risk of adverse pregnancy outcome. Current methods in the antenatal identification of placental dysfunction relies on estimates of fetal size and fetal wellbeing using ultrasound including Doppler flows measurements. These measurements are only indirect estimates of placental function, as no clinical method exists to assess placental function directly. In diabetic pregnancies, the estimates are further limited due to fetal overgrowth and unreliable Doppler. In addition, in diabetic pregnancies, intrauterine fetal weight estimates by ultrasound are inaccurate because of asymmetric fetal growth. Therefore, new accurate methods to assess placental function, fetal oxygenation and fetal growth in this particular group of high-risk pregnancies is highly needed. Early and precise identification of pathology in diabetes pregnancy may lead to an improved outcome in the offspring, as precise identification of pathology facilitates important obstetric decisions in regards to maternal antidiabetic treatment and timing of delivery. Resent research indicates that MRI is useful for this purpose. It is well described, that preeclampsia is associated with an increased maternal risk of cardiovascular disease later in life. Recent studies suggest, that pregestational subclinical cardiovascular dysfunction, in particular left ventricular dysfunction, may increase the risk of preeclampsia and fetal growth restriction during pregnancy. Cardiac MRI is a sensitive method to detect subclinical maternal cardiac dysfunction, which may be used in identification of high-risk pregnancies. In addition, the longitudinal design of this study allows for the investigation of cardiovascular changes during pregnancies in normal pregnancies and pregnancies complicated by diabetes. The overall aim of this study is to improve the antenatal fetal and maternal monitoring in diabetes pregnancies. Early and precise identification of pregnancy pathology provides a better basis for important obstetric decisions regarding antidiabetic treatment, monitoring intervals and timing of delivery, which leads to a better outcome for the mother and offspring. Hypothesis Project A: Placental function and fetal oxygenation in diabetic pregnancies estimated by T2\* weighted placental and fetal MRI Aim: To investigate placental function and fetal oxygenation by longitudinal T2\* weighted placental MRI and the association with pregnancy complications. Hypothesis: * Diabetic pregnancies are characterized by placental hypoxia (low T2\* value) * Diabetic pregnancies are characterized by fetal hypoxia (low T2\* value) * Fetal and placental hypoxia is a risk factor of placental related complications in pregnancy such as low birth weight, preterm delivery, acute cesarean sections and preeclampsia. Project B: Fetal growth and the growth of selected fetal organs in diabetic pregnancies estimated by longitudinal MRI volumetry Aim: To investigate growth velocity of the fetus and selected fetal organs and the correlation with pregnancy complications. Hypothesis: * Diabetic pregnancies are characterized by accelerated fetal growth in the third trimester * Diabetic pregnancies are characterized by asymmetric growth (reduced brain/liver-volume ratio) * Abnormal fetal growth is associated with dysregulated maternal diabetes. * Abnormal fetal growth is a risk factor of pregnancy complications such as; macrosomia, preterm delivery and acute cesarean sections. Project C: Maternal cardiac function in diabetic pregnancies estimated by MRI Aim: To investigate maternal cardiac function and the correlation with pregnancy complications such as preeclampsia and fetal growth restriction. Hypothesis: * Maternal cardiac function is altered in diabetes pregnancies when compared to normal pregnancies. * Impaired cardiac function (left ventricular dysfunction) is a risk factor of preeclampsia and fetal growth restriction.

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