Large for gestational age | |
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Classification and external resources | |
LGA: A healthy 5-kg (11-pound) newborn boy, delivered vaginally without complications (41 weeks; fourth child; no gestational diabetes) |
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ICD-10 | P08 |
ICD-9 | 766 |
DiseasesDB | 21929 |
MedlinePlus | 002251 |
eMedicine | med/3279 |
MeSH | D005320 |
Large for gestational age (LGA) is an indication of high prenatal growth rate, often defined as a weight (or length, or head circumference) that lies above the 90th percentile for that gestational age.[1] Macrosomia, also known as big baby syndrome, is sometimes used synonymously with LGA, or is otherwise defined as a fetus or infant that weighs above 4000 grams (8 lb 13 oz) or 4500 grams (9 lb 15 oz) regardless of gestational age.
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LGA is generally not diagnosed until after the birth, as the size and weight of the child is rarely checked during the latter stages of pregnancy. Babies that are large for gestational age throughout the pregnancy can sometimes be seen during a routine ultrasound, although fetal weight estimations late in pregnancy are quite imprecise.[2]
There are believed to be links with polyhydramnios (excessive amniotic sac fluid).
One of the primary risk factors is poorly-controlled diabetes, particularly gestational diabetes (GD),[3] as well as preexisting diabetes mellitus (preexisting type 2 is associated more with macrosomia, while preexisting type 1 can be associated with microsomia). This increases maternal plasma glucose levels as well as insulin, stimulating fetal growth. The LGA newborn exposed to maternal DM usually has an increase only in weight. LGA newborns that have complications other than exposure to maternal DM present with universal measurements >90th percentile.
Other determining factors include:
The condition is most common in mothers of African origin, partly due to the higher incidence of diabetes.
Depending upon the relative size of the head of the baby and the pelvic diameter of the mother vaginal birth may become complicated. One of the most common complications is shoulder dystocia. Such pregnancies often end in caesarean sections in order to safely deliver the baby and to avoid birth canal lacerations. Upon birth, early feeding is essential to prevent fetal hypoglycemia. Early diagnosis of individual problems is required.
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