Large Newborns for Gestational Age - Macrosomia

Large Newborns for Gestational Age - Macrosomia

  Autor dr. Molfea Camelia Data: 16.03.2006

Large Newborns for Gestational Age - Macrosomia
If a newborn has a weight above 4000 g both him and the mother are considered to have a n increased risk. These children are called LGA. 

The secondary causes of macrosomia, which lead to the fetal excessivegrowth, are the following:
  • glucose metabolism abnormalities 
  • mother's diabetes and high insulin level 
  • gestational diabetes (pregnancy diabetes) 
The pregnancy of women with diabetes is characterized by hyperglycemia in the third trimester. The glucose goes through the placenta and the fetus gets 75% of the glucose concentration of mother. 
The fetus increases the insulin secretion and thus becomes hyperinsulinemic (high insulin level in the blood) and excessively anabolic (the synthesis reactions are more than the degrading ones). It is also observed an increases synthesis of the triglycerides (a type of lipids) and an increase of the fat subcutaneous tissue (under skin). 
The fetus gets much weight before birth because of the homeostatic problems (a state when all the internal processes of the body function normally) of the mother. The weight growth is not associated with early maturation. These giant children are less mature than they seem to be. The difficulties to adapt to extra uterine life are not caused by their unusual sizes but by their poor metabolism. These children don't resist to a transient calorie diet (with low calories) which follows the pinching of the umbilical cord, because the hyperinsulinism (high insulin level in the blood) leads to an unwanted decrease of the glycemia level. Also, children with diabetic mothers have a higher risk to develop idiopatic respiratory distress (a pulmonary diseases characterized by the decrease of the oxygen in the blood). These children also have a higher risk of developing hypocalcemia, polycythemia (a high number of red blood cells in the blood), renal vein trombosis (obstruction of the renal vein caused by a clot of thrombus). Some children with large birth weight don't have diabetic mothers. Sometimes, this situation is caused by diseases such as feto-placental anasarca (a placenta abnormality which causes general edemas of the placenta and of the fetus) or placetal corioangioma (vascular disease of the placenta). 
The obese women often give birth to babies who have over 4000 g. Actually, it has been noticed that only 10% of mothers who give birth to LGA babies, have diabetes. 
Among the factors which determine a high probability to give birth to a LGA baby, we mention the multiparity (more than one baby) higher than four, excessive maternal weight gain, pregnancies beyond 40 weeks (294 days). An important consequence it's the fact that a child with large sizes may cause problems in case of natural birth or even prevent the normal birth process, can determine a longer and hard labor, or might need caesarean section from the beginning. Actually there is a high risk of complications or even death of the mother at birth. 

Also, the fetus with larger weight has a higher risk to be traumatized during the birth, or even to suffer severe hypoxia (reduced oxygen quantity in the blood), intracranial hemorrhage, clavicle fracture or brachial plexus palsy. Therefore, if the festus has a larger weight which doesn't allow him to be born naturally, the caesarean section is chosen. In both cases, you don't have to worry. Finally, the things will get better but a little harder in time. 

Read the English version of this article: Large Newborns for Gestational Age - Macrosomia