Handbook of Genetic Counseling/Diabetic Embryopathy

Diabetic Embryopathy

Etiology and natural history

 * 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

 * 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

 * 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

 * 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