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Handbook of Genetic Counseling/Diabetic Embryopathy

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Diabetic Embryopathy

Etiology and natural history

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  • Diabetic embryopathy is a clinical diagnosis based on one or more congenital anomalies or fetal/neonatal complications in a baby that are attributed to his/her mother's diabetes
  • Three main kinds of diabetes mellitus; if a mother has any of these three types, there is a significant risk for pregnancy complications and future health problems for mother and her offspring
    • Type I
      • Insulin dependent
      • Juvenile onset
      • Prone to ketosis
      • Body does not produce insulin because cells that produce insulin are attacked by immune system
      • Multifactorial causes, but those with family history are at higher risk
      • Tx: daily insulin injections
    • Type II
      • Non-insulin dependent
      • Adult onset
      • Not prone to ketosis
      • Body does not produce enough insulin or cells cannot use insulin properly
      • Inherited as an incompletely penetrating AR trait, but is definitely multifactorial
      • Tx: diet, exercise, and sometimes medication
    • Type III (Gestational diabetes)
      • Onset during pregnancy
      • Multifactorial causes, but those with family history of any diabetes are at higher risk
      • Tx: consistent monitoring of blood sugar level, diet and exercise; occasionally, insulin is required
      • Occurs in 1-4% of all pregnancies (higher in African American and Hispanic populations)
      • 20-50% of women who develop gestational diabetes will develop type II diabetes in the next 5-10 years.
  • High blood sugar levels and ketones (substances that in large amounts are poisonous to the body) pass through the placenta to the baby, increasing the chance of birth defects
  • When extra sugar is in a mother's blood during pregnancy, the baby is "fed" extra sugar, too, leading to a bigger baby that is harder to deliver
  • It is not well-understood if the administration of insulin has teratogenic effects on the fetus; however, outcomes are definitely better when insulin is used to treat insulin-dependent maternal diabetes than when not

Clinical features

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  • All maternal and fetal features noted here are more severe and/or common when diabetic control is poor during pregnancy; nevertheless, even with good diabetic control, these features are observed
  • Maternal morbidity factors in diabetic pregnancies which can increase a baby's risk for birth defects:
    • Ketoacidosis
    • Polyhydramnios
    • Preeclampsia/chronic hypertension
    • Preterm labor
    • Cesarean section
  • Fetal complications and birth defects associated with maternal diabetes
    • Cardiac anomalies: most commonly VSD or TGV
    • DiGeorge anomaly: due to abnormal neural crest cell migration; affects normal fetal development of the heart, thymus, and parathyroid glands
    • NTD's: thought to be due to maternal diabetic factors causing improper embryonic folding; most commonly spina bifida and anencephaly
    • Macrosomia: occurs in ~ 1/3 of all diabetic pregnancies; can cause life-long obesity for child
    • IUGR: thought to be due to nutrient limitation associated with maternal hypertension.
    • SAB: debated somewhat, but appears to be increased in pregnancies with poor diabetic control
    • Caudal regression: agenesis of sacrum and lumbar spine, hypoplasia of lower extremities; thought to be due to improper embryonic folding caused by maternal diabetic factors
    • Abnormal postnatal neurologic development: thought to be due to effects of ketosis
  • Perinatal and neonatal complications associated with maternal diabetes
    • Fetal asphyxia: can cause cerebral palsy as well as affecting many other systems such as pulmonary, GI, and cardiovascular
    • Preterm birth: can lead to respiratory distress syndrome; occurs in ~ 30% of diabetic pregnancies, even when diabetic control has been meticulous
    • Hypoglycemia: can cause seizures, coma, and brain damage if not recognized and treated quickly
    • Hypocalcemia and hypomagnesemia: thought to be caused primarily by premature birth and its affects on parathyroid function
    • Hyperbilirubinemia: thought to be caused primarily by premature birth
    • Cardiomyopathy and/or cardiomegaly: most commonly seen in macrosomic infants of poorly controlled diabetic mothers

Surveillance and Treatment

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  • Preconceptionally
    • Counseling recommended for all women with overt diabetes or a history of gestational diabetes
    • Severity of woman's disease should be considered
    • Woman should be apprised of possible complications to herself and her child
  • During pregnancy
    • Should be handled by a team of healthcare workers including: perinatologist, endocrinologist, dietician, and social worker
    • Patient should be seen every 4-8 weeks, and should be considered "high risk"
    • Mother should be closely monitored for diabetic control so that adjustments can be made for insulin, diet, and exercise
      • Insulin therapy can be altered in many ways, including continuous subcutaneous infusion if necessary
      • Must be careful to not over-insulinize mother and cause hypoglycemia
    • Surveillance for health risks to mother should be closely monitored, including: cardiovascular health, renal function, blood pressure, weight gain
    • Maternal serum screening should be done at 16 weeks
    • Fetus should be monitored regularly via level II ultrasound for detection of macrosomia, IUGR, cardiac anomalies, NTDs, and any other associated conditions
  • At birth
    • Delaying delivery until term is often contraindicated when baby is macrosomic or when mother is preeclampsic
    • Cesarean section rate is about 30-50% in diabetic pregnancies
    • Delivery should occur at facility prepared to deal with fetal and maternal complications associated with diabetic pregnancy
  • Postpartum management
    • Infant should be closely monitored for associated conditions; EKG and serum tests should be run
    • Mother's insulin should be closely monitored; many women need less insulin directly following delivery

Psychosocial issues

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  • Guilt on mother's part for risks and complications to her baby
  • Anxiety about own health due to having a high risk pregnancy
  • Financial concerns over costly prenatal and postnatal care
  • Fear about possible outcomes of pregnancy

Sources

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  • Creasy, RK and Resnik, R. 1994. Maternal-Fetal Medicine : Principles and Practice, 3rd ed. Ch. 54 : "Diabetes in pregnancy" (p.934-978). W.B. Saunders Company : Philadelphia.
  • American Diabetes Association Homepage-http://www.diabetes.org
  • Larsen, W.J. 2001. Human Embryology, 3rd ed. Churchill Livingstone : New York.

Notes

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The information in this outline was last updated in 2003.

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