Birth weight

From ArticleWorld

Babies born prematurely often are of a smaller birth weight than full term babies; however, they may be declared appropriate for gestational age (AGA). This means that the weight reflects the actual gestational age in which the child was born. Babies of any gestational age can be LGA or “large for gestational age” or SGA or “small for gestational age”. LGA babies are often referred to as having macrosomia, or the syndrome of being a large baby.

Technically, macrosomia is defined as a baby weighing greater than 4000 grams at term or 4500 grams at birth, regardless of gestational age. Low birth weight, on the other hand is defined as an infant of any gestational age that weighs less than 2500 grams.

Large for gestational age

There are several factors that result in an abnormally small or large birth weight. Large birth weights can be due to heredity, diabetes in the mother or to excessive weight gain in the mother during pregnancy. Diabetes in the mother can be related to the pregnancy itself (gestational diabetes) or to underlying diabetes.

Those mothers that keep the diabetes in good control often have better outcomes than those who let their diabetes lax during the pregnancy. High levels of maternal blood sugar trigger high insulin levels and high levels of hormones that promote fetal growth.

Small for gestational age

Infants who fall into the category of being less than 10% of expected weight are labeled SGA. Many factors can cause this condition. Any condition that results in a placenta that cannot keep up with the growing infant will result in an SGA baby. Poor nutrition, maternal drug or tobacco use and alcoholism are all linked to small birth weight babies. Certain blood conditions, such as anemia or clotting disorders, can affect the ability of the placenta to function.

Multiple pregnancies, such as twins or more, often result in small babies. Identical twins, for example, can have a condition where one twin steals nutrition from the other so that one twin is much larger than the other and the smaller twin is an SGA baby.

Maternal infections or chronic illnesses such as chronic kidney disease and sickle cell anemia can result in SGA infants due to placental insufficiency. Women with high blood pressure in pregnancy, a condition known as preeclampsia, have placentas that are insufficient for adequate fetal growth. In addition, if a pregnancy goes too long, the placenta can fail, resulting in weight loss in the developing fetus.