largeforgestation

Large-for-gestational-age (LGA) describes infants whose birth weight is above the 90th percentile for their gestational age, based on population or customized growth charts. Macrosomia is a related term often defined by a birth weight above about 4,000 g (8 lb 13 oz), though this absolute threshold varies by guideline and is distinct from LGA, which is percentile-based.

Risk factors include maternal diabetes (gestational or pregestational), maternal obesity, excessive weight gain during pregnancy, prior LGA infant, multiparity, advanced maternal age, and certain ethnic backgrounds. Fetal genetic factors and prolonged pregnancy can also contribute.

Diagnosis: Prenatally, estimated fetal weight by ultrasound may suggest excess size; postnatally, the newborn's birth weight is interpreted against gestational age-specific charts to determine LGA. Customized growth charts that adjust for maternal size and ethnicity may improve assessment.

Complications: LGA increases the risk of cesarean delivery and shoulder dystocia, birth injuries (for example brachial plexus), prolonged labor, and postpartum hemorrhage. In the newborn, there is higher risk of hypoglycemia, polycythemia, hypothermia, respiratory distress, and jaundice; potential longer-term risks include obesity and metabolic issues later in life, especially when associated with maternal diabetes.

Management: Prenatal care focuses on optimizing maternal metabolic control if diabetes, appropriate weight gain, and planning delivery timing. In labor, careful monitoring and consideration of mode of delivery are common; may favor planned delivery near term if risk of shoulder dystocia is high. Postnatal management includes monitoring glucose, maintaining warmth, early feeding, and pediatric evaluation as needed.