Large for gestational age
|Large for gestational age|
|Classification and external resources|
LGA: A healthy 5-kg (11-pound) newborn boy, delivered vaginally without complications (41 weeks; fourth child; no gestational diabetes)
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. 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.
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.
Predetermining factors 
One of the primary risk factors is poorly-controlled diabetes, particularly gestational diabetes (GD), as well as preexisting diabetes mellitus (DM) (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:
- Gestational age; pregnancies that go beyond 40 weeks increase incidence
- Fetal sex; male infants tend to weigh more than female infants
- Genetic factors; taller, heavier parents tend to have larger babies, with an obese mother greatly increasing the chances
- Excessive maternal weight gain
- Multiparity (have 2-3x the number of LGA infants vs. primaparas)
- Congenital anomalies (transposition of great vessels) - Hydrops Fetalis
- Erythroblastosis fetalis - Hydrops Fetalis
- Use of some antibiotics (amoxicillin, pivampicillin) during pregnancy - Hydrops Fetalis
- Genetic disorders of overgrowth (e.g. Beckwith-Wiedemann syndrome, Sotos syndrome)
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.
- "large-for-gestational-age infant" at Dorland's Medical Dictionary
- "Pregnancy - Experts: How accurate are fetal weight estimates? at Pregnancy & Baby". Retrieved 2007-11-28.
- Leipold H, Worda C, Gruber CJ, Kautzky-Willer A, Husslein PW, Bancher-Todesca D (August 2005). "Large-for-gestational-age newborns in women with insulin-treated gestational diabetes under strict metabolic control". Wien. Klin. Wochenschr. 117 (15-16): 521–5. doi:10.1007/s00508-005-0404-1. PMID 16160802.