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Fetal Macrosomia

Excessive birth weight is associated with an increased risk of maternal and neonatal injury. Macrosomia refers to a fetus with an estimated weight of more than 4,500 grams, regardless of gestational age.

Clinical estimates of fetal weight based on Leopold's maneuvers or fundal height measurements are unreliable and often inaccurate. Diagnosis of macrosomia requires ultrasound evaluation; however, estimation of fetal weight based on ultrasound is associated with a large margin of error. Maternal weight, height, previous obstetric history, fundal height, and the presence of gestational diabetes should be overweight baby, large baby

Factors Influencing Fetal Weight

Gestational Age. Post-term pregnancy is a risk factor. At 42 weeks and beyond, 2.5% of fetuses weigh more than 4,500 g. Ten to twenty percent of macrosomic infants were post-term fetuses. Maternal Weight. Heavy women have a greater risk of giving birth to excessively large infants. Fifteen to thirty five percent of women who deliver macrosomic fetuses weigh 90 kg or more.

Multiparity. Macrosomic infants are 2-3 times likely to be born to

Macrosomia in a Prior Infant. The risk of delivering an infant weighing more than 4,500 g is increased if a prior infant weighed more than

Maternal Diabetes increases the risk of fetal macrosomia and  

Cesarean delivery is indicated when the estimated fetal weight exceeds 4,500 g.

Morbidity and Mortality

Abnormalities of Labor. Macrosomic fetuses have a higher incidence of labor abnormalities and instrumental large baby deliveries.

Maternal Morbidity. Macrosomic fetuses have a two- to threefold increased rate of cesarean delivery.

Birth Injury

The incidence of birth injuries occurring during delivery of a macrosomic infant is much greater with vaginal than with