Gestational age Gestational Age Gestational age and growth parameters help identify the risk of neonatal pathology. Gestational age is the primary determinant of organ maturity. Neonatal gestational age is usually defined... read more is loosely defined as the number of weeks between the first day of the mother's last normal menstrual period and the day of delivery. More accurately, the gestational age is the difference between 14 days before the date of conception and the date of delivery. Gestational age is not the actual embryologic age of the fetus, but it is the universal standard among obstetricians and neonatologists for discussing fetal maturation.
The Fenton growth charts provide a more precise assessment of growth vs gestational age (see figures and ).
Etiology of LGA Infant
Other than genetically determined size, maternal diabetes mellitus Diabetes Mellitus in Pregnancy Pregnancy makes glycemic control more difficult in preexisting type 1 (insulin-dependent) and type 2 (non–insulin-dependent) diabetes but does not appear to exacerbate diabetic retinopathy,... read more is the major cause of large-for-gestational-age (LGA) infants. The large size results from the anabolic effects of high fetal insulin levels produced in response to excessive maternal blood glucose during gestation and sometimes increased caloric intake by the mother to compensate for glucose lost in urine. The less well controlled the mother’s diabetes during pregnancy, the larger is the size of the fetus.
Rare causes of macrosomia are Beckwith-Wiedemann syndrome (characterized by macrosomia, omphalocele, macroglossia, and hypoglycemia) and Sotos, Marshall, and Weaver syndromes.
Symptoms, Signs, and Treatment of LGA Infant
LGA infants are large and plethoric. The 5-minute may be low. These infants may be listless and limp and feed poorly.
Delivery complications can occur in any LGA infant. Congenital anomalies and some metabolic and cardiac complications are specific to LGA infants of mothers with diabetes.
Because of the infant’s large size, vaginal delivery may be difficult and occasionally results in birth injury Birth Injuries The forces of labor and delivery occasionally cause physical injury to the infant. The incidence of neonatal injury resulting from difficult or traumatic deliveries is decreasing due to increasing... read more , particularly including
Other complications occur when weight is > 4000 g. There is a proportional increase in morbidity and mortality because of the following:
Respiratory distress Respiratory Distress Syndrome in Neonates Respiratory distress syndrome is caused by pulmonary surfactant deficiency in the lungs of neonates, most commonly in those born at < 37 weeks gestation. Risk increases with degree of prematurity... read more (and need for ventilatory assistance)
Infants of mothers with diabetes
Infants of mothers with diabetes are at risk of
Hypocalcemia Neonatal Hypocalcemia Hypocalcemia is a total serum calcium concentration < 8 mg/dL (< 2 mmol/L) in term infants or < 7 mg/dL (< 1.75 mmol/L) in preterm infants. It is also defined as an ionized calcium... read more and hypomagnesemia Hypomagnesemia Hypomagnesemia is serum magnesium concentration < 1.8 mg/dL (< 0.70 mmol/L). Causes include inadequate magnesium intake and absorption or increased excretion due to hypercalcemia or medications... read more
Certain congenital anomalies
Hypoglycemia Neonatal Hypoglycemia Hypoglycemia is difficult to define in neonates but is generally considered a serum glucose concentration < 40 mg/dL (< 2.2 mmol/L) in symptomatic term neonates, < 45 mg/dL (< 2... read more is very likely in the first few hours after delivery because of the state of hyperinsulinism and the sudden termination of maternal glucose when the umbilical cord is cut. Neonatal hypoglycemia can be decreased by close prenatal control of the mother’s diabetes and early frequent feedings of the neonate. Blood glucose levels should be closely monitored by bedside testing from birth through at least the first 24 hours.
Treatment of hypoglycemia can range from enteral feeding orally or via nasogastric tube to IV administration of dextrose-containing fluids. Oral treatment with 40% glucose gel may prevent the need to separate the neonate from the mother for IV placement, but if there persistent hypoglycemia, parenteral dextrose-containing fluids are given IV. More evidence is needed about the effects of oral gel on long-term neurologic disability compared to other therapies for hypoglycemia (1 Reference Infants whose weight is > the 90th percentile for gestational age are classified as large for gestational age. Macrosomia is birthweight > 4000 g in a term infant. The predominant cause is... read more ).
Hypocalcemia Neonatal Hypocalcemia Hypocalcemia is a total serum calcium concentration < 8 mg/dL (< 2 mmol/L) in term infants or < 7 mg/dL (< 1.75 mmol/L) in preterm infants. It is also defined as an ionized calcium... read more and hypomagnesemia Hypomagnesemia Hypomagnesemia is serum magnesium concentration < 1.8 mg/dL (< 0.70 mmol/L). Causes include inadequate magnesium intake and absorption or increased excretion due to hypercalcemia or medications... read more may occur but are usually transient and asymptomatic. Good prenatal glycemic control decreases the risk of neonatal hypocalcemia. Hypocalcemia typically does not require treatment unless there are clinical signs of it or total serum calcium levels are < 7 mg/dL (< 1.75 mmol/L) or ionized calcium levels are < 4 mg/dL (< 1 mmol/L) in term infants. Treatment should be based on ionized calcium levels because these levels more accurately reflect available calcium. Treatment is usually given with IV supplementation of calcium gluconate. Hypomagnesemia can interfere with the secretion of parathyroid hormone, so hypocalcemia may not respond to treatment until the magnesium level is corrected.
Polycythemia Perinatal Polycythemia and Hyperviscosity Syndrome Polycythemia is an abnormal increase in red blood cell mass, defined in neonates as a venous hematocrit ≥ 65%; this increase can lead to hyperviscosity with sludging of blood within vessels... read more is slightly more common among infants of mothers with diabetes. Elevated insulin levels increase fetal metabolism and thus oxygen consumption. If the placenta is unable to meet the increased oxygen demand, fetal hypoxemia occurs, triggering an increase in erythropoietin and thus hematocrit.
Hyperbilirubinemia Neonatal Hyperbilirubinemia Jaundice is a yellow discoloration of the skin and eyes caused by hyperbilirubinemia (elevated serum bilirubin concentration). The serum bilirubin level required to cause jaundice varies with... read more occurs for several reasons. Infants of mothers with diabetes often have decreased tolerance for oral feedings (particularly when they are preterm) in the earliest days of life, which increases the enterohepatic circulation of bilirubin. Also, if polycythemia is present, the bilirubin load increases.
Respiratory distress syndrome Respiratory Distress Syndrome in Neonates Respiratory distress syndrome is caused by pulmonary surfactant deficiency in the lungs of neonates, most commonly in those born at < 37 weeks gestation. Risk increases with degree of prematurity... read more (RDS) may occur because elevated insulin levels decrease surfactant production; pulmonary maturation may thus be delayed until late in gestation. RDS may develop even if the infant is delivered late preterm or term. Treatment of respiratory distress syndrome Infants of mothers with diabetes is discussed elsewhere.
Congenital anomalies are more likely in infants of mothers with diabetes because maternal hyperglycemia at the time of organogenesis is detrimental. Specific anomalies include
Congenital heart disease Overview of Congenital Cardiovascular Anomalies Congenital heart disease is the most common congenital anomaly, occurring in almost 1% of live births ( 1). Among birth defects, congenital heart disease is the leading cause of infant mortality... read more (hypertrophic cardiomyopathy, ventricular septal defect, transposition of the great arteries, and aortic stenosis)
Caudal regression syndrome
Small left colon syndrome
Persistently elevated insulin levels can also lead to increased deposition of glycogen and fat into cardiomyocytes. This deposition can cause transient hypertrophic cardiomyopathy, predominantly of the septum.
Maternal diabetes mellitus is the major cause of large-for-gestational-age infants.
Large size itself increases risk of birth injury (eg, clavicle or extremity long bone fracture) and perinatal asphyxia.
Infants of mothers with diabetes also may have metabolic complications immediately after delivery, including hypoglycemia, hypocalcemia, and polycythemia.
Infants of mothers with diabetes are also at risk of respiratory distress syndrome and congenital anomalies.
Good control of maternal glucose levels minimizes risk of complications.
Drugs Mentioned In This Article
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|Advocate Glucose SOS, BD Glucose, Dex4 Glucose, Glutol , Glutose 15 , Glutose 45 , Glutose 5|