Sunday, October 21, 2012

Risk to babies born to Mother with Diabetes

Diabetes can occur in mother before pregnancy - pregestational diabetes or during pregnancy - gestational diabetes. High blood sugar level in mother is not just harmful to her but also to the baby developing in her womb.

HAZARDS DURING INTRAUTERINE LIFE

1. Congenital Anomalies or Birth Defects

The possibility of life-threatening structural anomalies is the most concerned issue in a case of maternal diabetes. Compared to a mother with normal blood glucose level, a mother with diabetes before pregnancy has 4 to 8 times higher risk of major fetal anomalies. According to studies, the defects mostly involve the brain and spinal cord, followed by heart, genitourinary system and limb defects.

However, there is no association of birth defects in offspring born to a diabetic father or in mother who develop diabetes after first trimester of pregnancy.

Why does birth defects occur in Infants of Diabetic Mother (IDM)?

Hyperglycemia disturbs the development of embryo by decreasing levels of arachidonic acid, myoinositol and accumulation of sorbitol and trace metals. These results were seen in animal studies. Fetal hyperglycemia, i.e. increased level of glucose in blood, promotes excessive formation of oxygen radicals which leads to tissue damage and disrupts the blood supply in developing tissues.

How can birth defects be prevented in IDM?

Normal glycemic control must be initiated before pregnancy to prevent these birth defects. The most critical period is 3 to 6 weeks after conception. Increased Glycated hemoglobin (HbA1c) which can be measured by laboratory blood testing has seen to be highly co-related with development of teratogenesis.

2. Macrosomia or Large Baby

Any newborn weighing more than 4 kg irrespective of gender and age of gestation are macrosomic or large babies. A study done in 1992 showed a clear preponderance of babies weighing more than 4.5 kg in mothers with diabetes compared to non-diabetic mothers. The hazards of macrosomia are:
Birth related injuries (Shoulder dystocia & Brachial plexus injury), asphyxia and increases the need of cesarean deliveries in mother.


Why do diabetic mother deliver large babies?

It has been seen that impaired glucose control in later 2 trimesters of pregnancy co-relate more with fetal obesity. The girth of abdomen increases significantly due to deposition of fat due to high glucose in fetal circulation. This leads to difficulty in normal delivery of the baby. Increased glucose level in mother leads to increased insulin secretion in fetus which leads to storage of excess nutrients.

How can macrosomia be prevented in IDM?

Strict blood glucose control in 2nd and 3rd trimester may reduce the incidence of large babies to near normal.

3. Fetal Hypoxia

Episodic maternal hyperglycemia promotes fetal catabolic state where excessive oxygen utilization occurs. Thus, causing decreased oxygen supply (hypoxia) to fetus.

HAZARDS AFTER BIRTH

1. Increased mortality and morbidity has been seen in Infants born to Diabetic Mothers (IDM) in 1st 28 days of life.

2. Birth injuries:

a. Shoulder dystocia: Difficulty in delivery of body of baby after the head has been delivered
b. Brachial plexus injury: Which can cause paralysis of upper limbs

3. Polycythemia: Fetal hypoxia stimulates secretion of erythropoietin from kidney, a hormone which has role in hemoglobin synthesis. This results in a condition called Polycythemia where there is increased level of hemoglobin in blood. Polycythemia in turn causes poor circulation and jaundice later on.

4. Hypoglycemia: Low blood sugar level in newborn can occur due to high insulin level causing symptoms like seizure, coma and brain damage during early life. Hence, blood sugar level monitoring is necessary during newborn period and is done as per standard protocol.

5. Jaundice or Hyperbilirubinemia: Prematurity and Polycythemia are the main factors contributing to jaundice in IDM. Jaundice may require phototherapy and rarely exchange transfusion.

6. Cardiomyopathy: Thickened heart musculature and septum have been described in IDM. 30% of infants have cardiomyopathy which resolve within 1 year.

7. Respiratory Distress Syndrome (RDS): Can result from prematurity, surfactant deficiency, fluid retention in lungs (transient tachypnea) and cardiomyopathy. Babies of mothers with poorly controlled blood glucose level have higher incidence of RDS.

Therefore, seeking medical attention to attain a normal glycemic state throughout the pregnancy is critical to prevent hazards to both baby and mother.

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